mirror of https://github.com/golang/go.git
crypto/elliptic: replace generic P-256 with fiat-crypto
For #52182 Change-Id: I8d8b4c3d8299fbd59b0bf48e5c8b7b41c533a2cc Reviewed-on: https://go-review.googlesource.com/c/go/+/360114 TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Roland Shoemaker <roland@golang.org> Run-TryBot: Filippo Valsorda <filippo@golang.org> Reviewed-by: Fernando Lobato Meeser <felobato@google.com>
This commit is contained in:
Filippo Valsorda
parent
2515a4214e
commit
68c2e9eede
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@ -30,15 +30,16 @@ var curves = []struct {
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FiatType: "[4]uint64",
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BytesLen: 28,
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},
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// The 32-bit pure Go P-256 in crypto/elliptic is still faster than the
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// autogenerated code here, regrettably.
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// {
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// Element: "P256Element",
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// Prime: "2^256 - 2^224 + 2^192 + 2^96 - 1",
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// Prefix: "p256",
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// FiatType: "[4]uint64",
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// BytesLen: 32,
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// },
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// The P-256 fiat implementation is used only on 32-bit architectures, but
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// the uint32 fiat code is for some reason slower than the uint64 one. That
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// suggests there is a wide margin for improvement.
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{
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Element: "P256Element",
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Prime: "2^256 - 2^224 + 2^192 + 2^96 - 1",
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Prefix: "p256",
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FiatType: "[4]uint64",
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BytesLen: 32,
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},
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{
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Element: "P384Element",
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Prime: "2^384 - 2^128 - 2^96 + 2^32 - 1",
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@ -0,0 +1,135 @@
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Code generated by generate.go. DO NOT EDIT.
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package fiat
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import (
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"crypto/subtle"
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"errors"
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)
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// P256Element is an integer modulo 2^256 - 2^224 + 2^192 + 2^96 - 1.
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//
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// The zero value is a valid zero element.
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type P256Element struct {
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// Values are represented internally always in the Montgomery domain, and
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// converted in Bytes and SetBytes.
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x p256MontgomeryDomainFieldElement
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}
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const p256ElementLen = 32
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type p256UntypedFieldElement = [4]uint64
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// One sets e = 1, and returns e.
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func (e *P256Element) One() *P256Element {
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p256SetOne(&e.x)
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return e
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}
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// Equal returns 1 if e == t, and zero otherwise.
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func (e *P256Element) Equal(t *P256Element) int {
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eBytes := e.Bytes()
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tBytes := t.Bytes()
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return subtle.ConstantTimeCompare(eBytes, tBytes)
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}
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var p256ZeroEncoding = new(P256Element).Bytes()
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// IsZero returns 1 if e == 0, and zero otherwise.
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func (e *P256Element) IsZero() int {
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eBytes := e.Bytes()
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return subtle.ConstantTimeCompare(eBytes, p256ZeroEncoding)
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}
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// Set sets e = t, and returns e.
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func (e *P256Element) Set(t *P256Element) *P256Element {
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e.x = t.x
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return e
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}
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// Bytes returns the 32-byte big-endian encoding of e.
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func (e *P256Element) Bytes() []byte {
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// This function is outlined to make the allocations inline in the caller
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// rather than happen on the heap.
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var out [p256ElementLen]byte
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return e.bytes(&out)
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}
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func (e *P256Element) bytes(out *[p256ElementLen]byte) []byte {
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var tmp p256NonMontgomeryDomainFieldElement
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p256FromMontgomery(&tmp, &e.x)
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p256ToBytes(out, (*p256UntypedFieldElement)(&tmp))
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p256InvertEndianness(out[:])
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return out[:]
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}
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// p256MinusOneEncoding is the encoding of -1 mod p, so p - 1, the
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// highest canonical encoding. It is used by SetBytes to check for non-canonical
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// encodings such as p + k, 2p + k, etc.
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var p256MinusOneEncoding = new(P256Element).Sub(
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new(P256Element), new(P256Element).One()).Bytes()
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// SetBytes sets e = v, where v is a big-endian 32-byte encoding, and returns e.
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// If v is not 32 bytes or it encodes a value higher than 2^256 - 2^224 + 2^192 + 2^96 - 1,
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// SetBytes returns nil and an error, and e is unchanged.
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func (e *P256Element) SetBytes(v []byte) (*P256Element, error) {
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if len(v) != p256ElementLen {
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return nil, errors.New("invalid P256Element encoding")
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}
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for i := range v {
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if v[i] < p256MinusOneEncoding[i] {
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break
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}
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if v[i] > p256MinusOneEncoding[i] {
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return nil, errors.New("invalid P256Element encoding")
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}
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}
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var in [p256ElementLen]byte
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copy(in[:], v)
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p256InvertEndianness(in[:])
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var tmp p256NonMontgomeryDomainFieldElement
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p256FromBytes((*p256UntypedFieldElement)(&tmp), &in)
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p256ToMontgomery(&e.x, &tmp)
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return e, nil
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}
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// Add sets e = t1 + t2, and returns e.
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func (e *P256Element) Add(t1, t2 *P256Element) *P256Element {
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p256Add(&e.x, &t1.x, &t2.x)
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return e
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}
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// Sub sets e = t1 - t2, and returns e.
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func (e *P256Element) Sub(t1, t2 *P256Element) *P256Element {
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p256Sub(&e.x, &t1.x, &t2.x)
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return e
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}
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// Mul sets e = t1 * t2, and returns e.
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func (e *P256Element) Mul(t1, t2 *P256Element) *P256Element {
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p256Mul(&e.x, &t1.x, &t2.x)
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return e
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}
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// Square sets e = t * t, and returns e.
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func (e *P256Element) Square(t *P256Element) *P256Element {
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p256Square(&e.x, &t.x)
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return e
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}
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// Select sets v to a if cond == 1, and to b if cond == 0.
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func (v *P256Element) Select(a, b *P256Element, cond int) *P256Element {
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p256Selectznz((*p256UntypedFieldElement)(&v.x), p256Uint1(cond),
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(*p256UntypedFieldElement)(&b.x), (*p256UntypedFieldElement)(&a.x))
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return v
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}
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func p256InvertEndianness(v []byte) {
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for i := 0; i < len(v)/2; i++ {
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v[i], v[len(v)-1-i] = v[len(v)-1-i], v[i]
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}
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}
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File diff suppressed because it is too large
Load Diff
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@ -0,0 +1,84 @@
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Code generated by addchain. DO NOT EDIT.
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package fiat
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// Invert sets e = 1/x, and returns e.
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//
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// If x == 0, Invert returns e = 0.
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func (e *P256Element) Invert(x *P256Element) *P256Element {
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// Inversion is implemented as exponentiation with exponent p − 2.
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// The sequence of 12 multiplications and 255 squarings is derived from the
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// following addition chain generated with github.com/mmcloughlin/addchain v0.4.0.
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//
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// _10 = 2*1
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// _11 = 1 + _10
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// _110 = 2*_11
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// _111 = 1 + _110
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// _111000 = _111 << 3
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// _111111 = _111 + _111000
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// x12 = _111111 << 6 + _111111
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// x15 = x12 << 3 + _111
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// x16 = 2*x15 + 1
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// x32 = x16 << 16 + x16
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// i53 = x32 << 15
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// x47 = x15 + i53
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// i263 = ((i53 << 17 + 1) << 143 + x47) << 47
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// return (x47 + i263) << 2 + 1
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//
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var z = new(P256Element).Set(e)
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var t0 = new(P256Element)
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var t1 = new(P256Element)
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z.Square(x)
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z.Mul(x, z)
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z.Square(z)
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z.Mul(x, z)
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t0.Square(z)
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for s := 1; s < 3; s++ {
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t0.Square(t0)
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}
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t0.Mul(z, t0)
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t1.Square(t0)
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for s := 1; s < 6; s++ {
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t1.Square(t1)
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}
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t0.Mul(t0, t1)
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for s := 0; s < 3; s++ {
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t0.Square(t0)
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}
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z.Mul(z, t0)
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t0.Square(z)
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t0.Mul(x, t0)
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t1.Square(t0)
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for s := 1; s < 16; s++ {
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t1.Square(t1)
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}
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t0.Mul(t0, t1)
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for s := 0; s < 15; s++ {
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t0.Square(t0)
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}
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z.Mul(z, t0)
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for s := 0; s < 17; s++ {
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t0.Square(t0)
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}
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t0.Mul(x, t0)
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for s := 0; s < 143; s++ {
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t0.Square(t0)
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}
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t0.Mul(z, t0)
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for s := 0; s < 47; s++ {
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t0.Square(t0)
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}
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z.Mul(z, t0)
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for s := 0; s < 2; s++ {
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z.Square(z)
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}
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z.Mul(x, z)
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return e.Set(z)
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}
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@ -28,6 +28,11 @@ var curves = []struct {
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Element: "fiat.P224Element",
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Params: elliptic.P224().Params(),
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},
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{
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P: "P256",
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Element: "fiat.P256Element",
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Params: elliptic.P256().Params(),
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},
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{
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P: "P384",
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Element: "fiat.P384Element",
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@ -5,6 +5,7 @@
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package nistec_test
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import (
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"bytes"
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"crypto/elliptic/internal/nistec"
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"math/rand"
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"os"
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@ -19,7 +20,21 @@ func TestAllocations(t *testing.T) {
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t.Run("P224", func(t *testing.T) {
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if allocs := testing.AllocsPerRun(100, func() {
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p := nistec.NewP224Generator()
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scalar := make([]byte, 66)
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scalar := make([]byte, 28)
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rand.Read(scalar)
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p.ScalarMult(p, scalar)
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out := p.Bytes()
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if _, err := p.SetBytes(out); err != nil {
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t.Fatal(err)
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}
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}); allocs > 0 {
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t.Errorf("expected zero allocations, got %0.1f", allocs)
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}
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})
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t.Run("P256", func(t *testing.T) {
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if allocs := testing.AllocsPerRun(100, func() {
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p := nistec.NewP256Generator()
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scalar := make([]byte, 32)
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rand.Read(scalar)
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p.ScalarMult(p, scalar)
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out := p.Bytes()
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@ -33,7 +48,7 @@ func TestAllocations(t *testing.T) {
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t.Run("P384", func(t *testing.T) {
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if allocs := testing.AllocsPerRun(100, func() {
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p := nistec.NewP384Generator()
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scalar := make([]byte, 66)
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scalar := make([]byte, 48)
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rand.Read(scalar)
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p.ScalarMult(p, scalar)
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out := p.Bytes()
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@ -60,35 +75,65 @@ func TestAllocations(t *testing.T) {
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})
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}
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func BenchmarkScalarMult(b *testing.B) {
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b.Run("P224", func(b *testing.B) {
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scalar := make([]byte, 66)
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rand.Read(scalar)
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p := nistec.NewP224Generator()
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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p.ScalarMult(p, scalar)
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}
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type nistPoint[T any] interface {
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Bytes() []byte
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SetBytes([]byte) (T, error)
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Add(T, T) T
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Double(T) T
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ScalarMult(T, []byte) T
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}
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func TestEquivalents(t *testing.T) {
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t.Run("P224", func(t *testing.T) {
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testEquivalents(t, nistec.NewP224Point, nistec.NewP224Generator)
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})
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b.Run("P384", func(b *testing.B) {
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scalar := make([]byte, 66)
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rand.Read(scalar)
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p := nistec.NewP384Generator()
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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p.ScalarMult(p, scalar)
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}
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t.Run("P256", func(t *testing.T) {
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testEquivalents(t, nistec.NewP256Point, nistec.NewP256Generator)
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})
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b.Run("P521", func(b *testing.B) {
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scalar := make([]byte, 66)
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rand.Read(scalar)
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p := nistec.NewP521Generator()
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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p.ScalarMult(p, scalar)
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}
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t.Run("P384", func(t *testing.T) {
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testEquivalents(t, nistec.NewP384Point, nistec.NewP384Generator)
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})
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t.Run("P521", func(t *testing.T) {
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testEquivalents(t, nistec.NewP521Point, nistec.NewP521Generator)
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})
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}
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func testEquivalents[P nistPoint[P]](t *testing.T, newPoint, newGenerator func() P) {
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p := newGenerator()
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p1 := newPoint().Double(p)
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p2 := newPoint().Add(p, p)
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p3 := newPoint().ScalarMult(p, []byte{2})
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if !bytes.Equal(p1.Bytes(), p2.Bytes()) {
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t.Error("P+P != 2*P")
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}
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if !bytes.Equal(p1.Bytes(), p3.Bytes()) {
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t.Error("P+P != [2]P")
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}
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}
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func BenchmarkScalarMult(b *testing.B) {
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b.Run("P224", func(b *testing.B) {
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benchmarkScalarMult(b, nistec.NewP224Generator(), 28)
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})
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b.Run("P256", func(b *testing.B) {
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benchmarkScalarMult(b, nistec.NewP256Generator(), 32)
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})
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b.Run("P384", func(b *testing.B) {
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benchmarkScalarMult(b, nistec.NewP384Generator(), 48)
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})
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b.Run("P521", func(b *testing.B) {
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benchmarkScalarMult(b, nistec.NewP521Generator(), 66)
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})
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}
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func benchmarkScalarMult[P nistPoint[P]](b *testing.B, p P, scalarSize int) {
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scalar := make([]byte, scalarSize)
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rand.Read(scalar)
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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p.ScalarMult(p, scalar)
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}
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}
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@ -0,0 +1,288 @@
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// Copyright 2022 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
|
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// license that can be found in the LICENSE file.
|
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|
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// Code generated by generate.go. DO NOT EDIT.
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package nistec
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import (
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"crypto/elliptic/internal/fiat"
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"crypto/subtle"
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"errors"
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)
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var p256B, _ = new(fiat.P256Element).SetBytes([]byte{0x5a, 0xc6, 0x35, 0xd8, 0xaa, 0x3a, 0x93, 0xe7, 0xb3, 0xeb, 0xbd, 0x55, 0x76, 0x98, 0x86, 0xbc, 0x65, 0x1d, 0x6, 0xb0, 0xcc, 0x53, 0xb0, 0xf6, 0x3b, 0xce, 0x3c, 0x3e, 0x27, 0xd2, 0x60, 0x4b})
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var p256G, _ = NewP256Point().SetBytes([]byte{0x4, 0x6b, 0x17, 0xd1, 0xf2, 0xe1, 0x2c, 0x42, 0x47, 0xf8, 0xbc, 0xe6, 0xe5, 0x63, 0xa4, 0x40, 0xf2, 0x77, 0x3, 0x7d, 0x81, 0x2d, 0xeb, 0x33, 0xa0, 0xf4, 0xa1, 0x39, 0x45, 0xd8, 0x98, 0xc2, 0x96, 0x4f, 0xe3, 0x42, 0xe2, 0xfe, 0x1a, 0x7f, 0x9b, 0x8e, 0xe7, 0xeb, 0x4a, 0x7c, 0xf, 0x9e, 0x16, 0x2b, 0xce, 0x33, 0x57, 0x6b, 0x31, 0x5e, 0xce, 0xcb, 0xb6, 0x40, 0x68, 0x37, 0xbf, 0x51, 0xf5})
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const p256ElementLength = 32
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// P256Point is a P256 point. The zero value is NOT valid.
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type P256Point struct {
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// The point is represented in projective coordinates (X:Y:Z),
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// where x = X/Z and y = Y/Z.
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x, y, z *fiat.P256Element
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}
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||||
// NewP256Point returns a new P256Point representing the point at infinity point.
|
||||
func NewP256Point() *P256Point {
|
||||
return &P256Point{
|
||||
x: new(fiat.P256Element),
|
||||
y: new(fiat.P256Element).One(),
|
||||
z: new(fiat.P256Element),
|
||||
}
|
||||
}
|
||||
|
||||
// NewP256Generator returns a new P256Point set to the canonical generator.
|
||||
func NewP256Generator() *P256Point {
|
||||
return (&P256Point{
|
||||
x: new(fiat.P256Element),
|
||||
y: new(fiat.P256Element),
|
||||
z: new(fiat.P256Element),
|
||||
}).Set(p256G)
|
||||
}
|
||||
|
||||
// Set sets p = q and returns p.
|
||||
func (p *P256Point) Set(q *P256Point) *P256Point {
|
||||
p.x.Set(q.x)
|
||||
p.y.Set(q.y)
|
||||
p.z.Set(q.z)
|
||||
return p
|
||||
}
|
||||
|
||||
// SetBytes sets p to the compressed, uncompressed, or infinity value encoded in
|
||||
// b, as specified in SEC 1, Version 2.0, Section 2.3.4. If the point is not on
|
||||
// the curve, it returns nil and an error, and the receiver is unchanged.
|
||||
// Otherwise, it returns p.
|
||||
func (p *P256Point) SetBytes(b []byte) (*P256Point, error) {
|
||||
switch {
|
||||
// Point at infinity.
|
||||
case len(b) == 1 && b[0] == 0:
|
||||
return p.Set(NewP256Point()), nil
|
||||
|
||||
// Uncompressed form.
|
||||
case len(b) == 1+2*p256ElementLength && b[0] == 4:
|
||||
x, err := new(fiat.P256Element).SetBytes(b[1 : 1+p256ElementLength])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
y, err := new(fiat.P256Element).SetBytes(b[1+p256ElementLength:])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
if err := p256CheckOnCurve(x, y); err != nil {
|
||||
return nil, err
|
||||
}
|
||||
p.x.Set(x)
|
||||
p.y.Set(y)
|
||||
p.z.One()
|
||||
return p, nil
|
||||
|
||||
// Compressed form
|
||||
case len(b) == 1+p256ElementLength && b[0] == 0:
|
||||
return nil, errors.New("unimplemented") // TODO(filippo)
|
||||
|
||||
default:
|
||||
return nil, errors.New("invalid P256 point encoding")
|
||||
}
|
||||
}
|
||||
|
||||
func p256CheckOnCurve(x, y *fiat.P256Element) error {
|
||||
// x³ - 3x + b.
|
||||
x3 := new(fiat.P256Element).Square(x)
|
||||
x3.Mul(x3, x)
|
||||
|
||||
threeX := new(fiat.P256Element).Add(x, x)
|
||||
threeX.Add(threeX, x)
|
||||
|
||||
x3.Sub(x3, threeX)
|
||||
x3.Add(x3, p256B)
|
||||
|
||||
// y² = x³ - 3x + b
|
||||
y2 := new(fiat.P256Element).Square(y)
|
||||
|
||||
if x3.Equal(y2) != 1 {
|
||||
return errors.New("P256 point not on curve")
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// Bytes returns the uncompressed or infinity encoding of p, as specified in
|
||||
// SEC 1, Version 2.0, Section 2.3.3. Note that the encoding of the point at
|
||||
// infinity is shorter than all other encodings.
|
||||
func (p *P256Point) Bytes() []byte {
|
||||
// This function is outlined to make the allocations inline in the caller
|
||||
// rather than happen on the heap.
|
||||
var out [133]byte
|
||||
return p.bytes(&out)
|
||||
}
|
||||
|
||||
func (p *P256Point) bytes(out *[133]byte) []byte {
|
||||
if p.z.IsZero() == 1 {
|
||||
return append(out[:0], 0)
|
||||
}
|
||||
|
||||
zinv := new(fiat.P256Element).Invert(p.z)
|
||||
xx := new(fiat.P256Element).Mul(p.x, zinv)
|
||||
yy := new(fiat.P256Element).Mul(p.y, zinv)
|
||||
|
||||
buf := append(out[:0], 4)
|
||||
buf = append(buf, xx.Bytes()...)
|
||||
buf = append(buf, yy.Bytes()...)
|
||||
return buf
|
||||
}
|
||||
|
||||
// Add sets q = p1 + p2, and returns q. The points may overlap.
|
||||
func (q *P256Point) Add(p1, p2 *P256Point) *P256Point {
|
||||
// Complete addition formula for a = -3 from "Complete addition formulas for
|
||||
// prime order elliptic curves" (https://eprint.iacr.org/2015/1060), §A.2.
|
||||
|
||||
t0 := new(fiat.P256Element).Mul(p1.x, p2.x) // t0 := X1 * X2
|
||||
t1 := new(fiat.P256Element).Mul(p1.y, p2.y) // t1 := Y1 * Y2
|
||||
t2 := new(fiat.P256Element).Mul(p1.z, p2.z) // t2 := Z1 * Z2
|
||||
t3 := new(fiat.P256Element).Add(p1.x, p1.y) // t3 := X1 + Y1
|
||||
t4 := new(fiat.P256Element).Add(p2.x, p2.y) // t4 := X2 + Y2
|
||||
t3.Mul(t3, t4) // t3 := t3 * t4
|
||||
t4.Add(t0, t1) // t4 := t0 + t1
|
||||
t3.Sub(t3, t4) // t3 := t3 - t4
|
||||
t4.Add(p1.y, p1.z) // t4 := Y1 + Z1
|
||||
x3 := new(fiat.P256Element).Add(p2.y, p2.z) // X3 := Y2 + Z2
|
||||
t4.Mul(t4, x3) // t4 := t4 * X3
|
||||
x3.Add(t1, t2) // X3 := t1 + t2
|
||||
t4.Sub(t4, x3) // t4 := t4 - X3
|
||||
x3.Add(p1.x, p1.z) // X3 := X1 + Z1
|
||||
y3 := new(fiat.P256Element).Add(p2.x, p2.z) // Y3 := X2 + Z2
|
||||
x3.Mul(x3, y3) // X3 := X3 * Y3
|
||||
y3.Add(t0, t2) // Y3 := t0 + t2
|
||||
y3.Sub(x3, y3) // Y3 := X3 - Y3
|
||||
z3 := new(fiat.P256Element).Mul(p256B, t2) // Z3 := b * t2
|
||||
x3.Sub(y3, z3) // X3 := Y3 - Z3
|
||||
z3.Add(x3, x3) // Z3 := X3 + X3
|
||||
x3.Add(x3, z3) // X3 := X3 + Z3
|
||||
z3.Sub(t1, x3) // Z3 := t1 - X3
|
||||
x3.Add(t1, x3) // X3 := t1 + X3
|
||||
y3.Mul(p256B, y3) // Y3 := b * Y3
|
||||
t1.Add(t2, t2) // t1 := t2 + t2
|
||||
t2.Add(t1, t2) // t2 := t1 + t2
|
||||
y3.Sub(y3, t2) // Y3 := Y3 - t2
|
||||
y3.Sub(y3, t0) // Y3 := Y3 - t0
|
||||
t1.Add(y3, y3) // t1 := Y3 + Y3
|
||||
y3.Add(t1, y3) // Y3 := t1 + Y3
|
||||
t1.Add(t0, t0) // t1 := t0 + t0
|
||||
t0.Add(t1, t0) // t0 := t1 + t0
|
||||
t0.Sub(t0, t2) // t0 := t0 - t2
|
||||
t1.Mul(t4, y3) // t1 := t4 * Y3
|
||||
t2.Mul(t0, y3) // t2 := t0 * Y3
|
||||
y3.Mul(x3, z3) // Y3 := X3 * Z3
|
||||
y3.Add(y3, t2) // Y3 := Y3 + t2
|
||||
x3.Mul(t3, x3) // X3 := t3 * X3
|
||||
x3.Sub(x3, t1) // X3 := X3 - t1
|
||||
z3.Mul(t4, z3) // Z3 := t4 * Z3
|
||||
t1.Mul(t3, t0) // t1 := t3 * t0
|
||||
z3.Add(z3, t1) // Z3 := Z3 + t1
|
||||
|
||||
q.x.Set(x3)
|
||||
q.y.Set(y3)
|
||||
q.z.Set(z3)
|
||||
return q
|
||||
}
|
||||
|
||||
// Double sets q = p + p, and returns q. The points may overlap.
|
||||
func (q *P256Point) Double(p *P256Point) *P256Point {
|
||||
// Complete addition formula for a = -3 from "Complete addition formulas for
|
||||
// prime order elliptic curves" (https://eprint.iacr.org/2015/1060), §A.2.
|
||||
|
||||
t0 := new(fiat.P256Element).Square(p.x) // t0 := X ^ 2
|
||||
t1 := new(fiat.P256Element).Square(p.y) // t1 := Y ^ 2
|
||||
t2 := new(fiat.P256Element).Square(p.z) // t2 := Z ^ 2
|
||||
t3 := new(fiat.P256Element).Mul(p.x, p.y) // t3 := X * Y
|
||||
t3.Add(t3, t3) // t3 := t3 + t3
|
||||
z3 := new(fiat.P256Element).Mul(p.x, p.z) // Z3 := X * Z
|
||||
z3.Add(z3, z3) // Z3 := Z3 + Z3
|
||||
y3 := new(fiat.P256Element).Mul(p256B, t2) // Y3 := b * t2
|
||||
y3.Sub(y3, z3) // Y3 := Y3 - Z3
|
||||
x3 := new(fiat.P256Element).Add(y3, y3) // X3 := Y3 + Y3
|
||||
y3.Add(x3, y3) // Y3 := X3 + Y3
|
||||
x3.Sub(t1, y3) // X3 := t1 - Y3
|
||||
y3.Add(t1, y3) // Y3 := t1 + Y3
|
||||
y3.Mul(x3, y3) // Y3 := X3 * Y3
|
||||
x3.Mul(x3, t3) // X3 := X3 * t3
|
||||
t3.Add(t2, t2) // t3 := t2 + t2
|
||||
t2.Add(t2, t3) // t2 := t2 + t3
|
||||
z3.Mul(p256B, z3) // Z3 := b * Z3
|
||||
z3.Sub(z3, t2) // Z3 := Z3 - t2
|
||||
z3.Sub(z3, t0) // Z3 := Z3 - t0
|
||||
t3.Add(z3, z3) // t3 := Z3 + Z3
|
||||
z3.Add(z3, t3) // Z3 := Z3 + t3
|
||||
t3.Add(t0, t0) // t3 := t0 + t0
|
||||
t0.Add(t3, t0) // t0 := t3 + t0
|
||||
t0.Sub(t0, t2) // t0 := t0 - t2
|
||||
t0.Mul(t0, z3) // t0 := t0 * Z3
|
||||
y3.Add(y3, t0) // Y3 := Y3 + t0
|
||||
t0.Mul(p.y, p.z) // t0 := Y * Z
|
||||
t0.Add(t0, t0) // t0 := t0 + t0
|
||||
z3.Mul(t0, z3) // Z3 := t0 * Z3
|
||||
x3.Sub(x3, z3) // X3 := X3 - Z3
|
||||
z3.Mul(t0, t1) // Z3 := t0 * t1
|
||||
z3.Add(z3, z3) // Z3 := Z3 + Z3
|
||||
z3.Add(z3, z3) // Z3 := Z3 + Z3
|
||||
|
||||
q.x.Set(x3)
|
||||
q.y.Set(y3)
|
||||
q.z.Set(z3)
|
||||
return q
|
||||
}
|
||||
|
||||
// Select sets q to p1 if cond == 1, and to p2 if cond == 0.
|
||||
func (q *P256Point) Select(p1, p2 *P256Point, cond int) *P256Point {
|
||||
q.x.Select(p1.x, p2.x, cond)
|
||||
q.y.Select(p1.y, p2.y, cond)
|
||||
q.z.Select(p1.z, p2.z, cond)
|
||||
return q
|
||||
}
|
||||
|
||||
// ScalarMult sets p = scalar * q, and returns p.
|
||||
func (p *P256Point) ScalarMult(q *P256Point, scalar []byte) *P256Point {
|
||||
// table holds the first 16 multiples of q. The explicit newP256Point calls
|
||||
// get inlined, letting the allocations live on the stack.
|
||||
var table = [16]*P256Point{
|
||||
NewP256Point(), NewP256Point(), NewP256Point(), NewP256Point(),
|
||||
NewP256Point(), NewP256Point(), NewP256Point(), NewP256Point(),
|
||||
NewP256Point(), NewP256Point(), NewP256Point(), NewP256Point(),
|
||||
NewP256Point(), NewP256Point(), NewP256Point(), NewP256Point(),
|
||||
}
|
||||
for i := 1; i < 16; i++ {
|
||||
table[i].Add(table[i-1], q)
|
||||
}
|
||||
|
||||
// Instead of doing the classic double-and-add chain, we do it with a
|
||||
// four-bit window: we double four times, and then add [0-15]P.
|
||||
t := NewP256Point()
|
||||
p.Set(NewP256Point())
|
||||
for _, byte := range scalar {
|
||||
p.Double(p)
|
||||
p.Double(p)
|
||||
p.Double(p)
|
||||
p.Double(p)
|
||||
|
||||
for i := uint8(0); i < 16; i++ {
|
||||
cond := subtle.ConstantTimeByteEq(byte>>4, i)
|
||||
t.Select(table[i], t, cond)
|
||||
}
|
||||
p.Add(p, t)
|
||||
|
||||
p.Double(p)
|
||||
p.Double(p)
|
||||
p.Double(p)
|
||||
p.Double(p)
|
||||
|
||||
for i := uint8(0); i < 16; i++ {
|
||||
cond := subtle.ConstantTimeByteEq(byte&0b1111, i)
|
||||
t.Select(table[i], t, cond)
|
||||
}
|
||||
p.Add(p, t)
|
||||
}
|
||||
|
||||
return p
|
||||
}
|
||||
|
|
@ -29,6 +29,36 @@ func initP224() {
|
|||
}
|
||||
}
|
||||
|
||||
var p256Params CurveParams
|
||||
|
||||
var p256 Curve = &nistCurve[*nistec.P256Point]{
|
||||
params: &p256Params,
|
||||
newPoint: nistec.NewP256Point,
|
||||
newGenerator: nistec.NewP256Generator,
|
||||
}
|
||||
|
||||
var initP256Arch func()
|
||||
|
||||
func initP256() {
|
||||
p256Params = CurveParams{
|
||||
Name: "P-256",
|
||||
BitSize: 256,
|
||||
// FIPS 186-4, section D.1.2.3
|
||||
P: bigFromDecimal("115792089210356248762697446949407573530086143415290314195533631308867097853951"),
|
||||
N: bigFromDecimal("115792089210356248762697446949407573529996955224135760342422259061068512044369"),
|
||||
B: bigFromHex("5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b"),
|
||||
Gx: bigFromHex("6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296"),
|
||||
Gy: bigFromHex("4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5"),
|
||||
}
|
||||
|
||||
// P-256 is implemented by various different backends, including a generic
|
||||
// 32-bit constant-time one in internal/nistec, which is used when assembly
|
||||
// implementations are not available, or not appropriate for the hardware.
|
||||
if initP256Arch != nil {
|
||||
initP256Arch()
|
||||
}
|
||||
}
|
||||
|
||||
var p384 = &nistCurve[*nistec.P384Point]{
|
||||
newPoint: nistec.NewP384Point,
|
||||
newGenerator: nistec.NewP384Generator,
|
||||
|
|
|
|||
|
|
@ -1,32 +0,0 @@
|
|||
// Copyright 2021 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
package elliptic
|
||||
|
||||
// P-256 is implemented by various different backends, including a generic
|
||||
// 32-bit constant-time one in p256_generic.go, which is used when assembly
|
||||
// implementations are not available, or not appropriate for the hardware.
|
||||
|
||||
import "math/big"
|
||||
|
||||
var p256Params *CurveParams
|
||||
|
||||
// RInverse contains 1/R mod p, the inverse of the Montgomery constant 2^257.
|
||||
var p256RInverse *big.Int
|
||||
|
||||
func initP256() {
|
||||
// See FIPS 186-3, section D.2.3
|
||||
p256Params = &CurveParams{Name: "P-256"}
|
||||
p256Params.P, _ = new(big.Int).SetString("115792089210356248762697446949407573530086143415290314195533631308867097853951", 10)
|
||||
p256Params.N, _ = new(big.Int).SetString("115792089210356248762697446949407573529996955224135760342422259061068512044369", 10)
|
||||
p256Params.B, _ = new(big.Int).SetString("5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b", 16)
|
||||
p256Params.Gx, _ = new(big.Int).SetString("6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296", 16)
|
||||
p256Params.Gy, _ = new(big.Int).SetString("4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5", 16)
|
||||
p256Params.BitSize = 256
|
||||
|
||||
p256RInverse, _ = new(big.Int).SetString("7fffffff00000001fffffffe8000000100000000ffffffff0000000180000000", 16)
|
||||
|
||||
// Arch-specific initialization, i.e. let a platform dynamically pick a P256 implementation
|
||||
initP256Arch()
|
||||
}
|
||||
|
|
@ -32,10 +32,10 @@ type p256Point struct {
|
|||
xyz [12]uint64
|
||||
}
|
||||
|
||||
var p256 p256Curve
|
||||
|
||||
func initP256Arch() {
|
||||
p256 = p256Curve{p256Params}
|
||||
func init() {
|
||||
initP256Arch = func() {
|
||||
p256 = p256Curve{&p256Params}
|
||||
}
|
||||
}
|
||||
|
||||
func (curve p256Curve) Params() *CurveParams {
|
||||
|
|
@ -120,9 +120,9 @@ func (curve p256Curve) Inverse(k *big.Int) *big.Int {
|
|||
k = new(big.Int).Neg(k)
|
||||
}
|
||||
|
||||
if k.Cmp(p256.N) >= 0 {
|
||||
if k.Cmp(p256Params.N) >= 0 {
|
||||
// This should never happen.
|
||||
k = new(big.Int).Mod(k, p256.N)
|
||||
k = new(big.Int).Mod(k, p256Params.N)
|
||||
}
|
||||
|
||||
// table will store precomputed powers of x.
|
||||
|
|
@ -218,8 +218,8 @@ func fromBig(out []uint64, big *big.Int) {
|
|||
func p256GetScalar(out []uint64, in []byte) {
|
||||
n := new(big.Int).SetBytes(in)
|
||||
|
||||
if n.Cmp(p256.N) >= 0 {
|
||||
n.Mod(n, p256.N)
|
||||
if n.Cmp(p256Params.N) >= 0 {
|
||||
n.Mod(n, p256Params.N)
|
||||
}
|
||||
fromBig(out, n)
|
||||
}
|
||||
|
|
@ -230,10 +230,10 @@ func p256GetScalar(out []uint64, in []byte) {
|
|||
var rr = []uint64{0x0000000000000003, 0xfffffffbffffffff, 0xfffffffffffffffe, 0x00000004fffffffd}
|
||||
|
||||
func maybeReduceModP(in *big.Int) *big.Int {
|
||||
if in.Cmp(p256.P) < 0 {
|
||||
if in.Cmp(p256Params.P) < 0 {
|
||||
return in
|
||||
}
|
||||
return new(big.Int).Mod(in, p256.P)
|
||||
return new(big.Int).Mod(in, p256Params.P)
|
||||
}
|
||||
|
||||
func (curve p256Curve) CombinedMult(bigX, bigY *big.Int, baseScalar, scalar []byte) (x, y *big.Int) {
|
||||
|
|
|
|||
|
|
@ -1,477 +0,0 @@
|
|||
// Copyright 2013 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
//go:build !amd64 && !arm64
|
||||
|
||||
package elliptic
|
||||
|
||||
// This file contains a constant-time, 32-bit implementation of P256.
|
||||
|
||||
import "math/big"
|
||||
|
||||
type p256Curve struct {
|
||||
*CurveParams
|
||||
}
|
||||
|
||||
func (curve p256Curve) Params() *CurveParams {
|
||||
return curve.CurveParams
|
||||
}
|
||||
|
||||
// p256GetScalar endian-swaps the big-endian scalar value from in and writes it
|
||||
// to out. If the scalar is equal or greater than the order of the group, it's
|
||||
// reduced modulo that order.
|
||||
func p256GetScalar(out *[32]byte, in []byte) {
|
||||
n := new(big.Int).SetBytes(in)
|
||||
var scalarBytes []byte
|
||||
|
||||
if n.Cmp(p256Params.N) >= 0 || len(in) > len(out) {
|
||||
n.Mod(n, p256Params.N)
|
||||
scalarBytes = n.Bytes()
|
||||
} else {
|
||||
scalarBytes = in
|
||||
}
|
||||
|
||||
for i, v := range scalarBytes {
|
||||
out[len(scalarBytes)-(1+i)] = v
|
||||
}
|
||||
}
|
||||
|
||||
func (p256Curve) ScalarBaseMult(scalar []byte) (x, y *big.Int) {
|
||||
var scalarReversed [32]byte
|
||||
p256GetScalar(&scalarReversed, scalar)
|
||||
|
||||
var x1, y1, z1 [p256Limbs]uint32
|
||||
p256ScalarBaseMult(&x1, &y1, &z1, &scalarReversed)
|
||||
return p256ToAffine(&x1, &y1, &z1)
|
||||
}
|
||||
|
||||
func (p256Curve) ScalarMult(bigX, bigY *big.Int, scalar []byte) (x, y *big.Int) {
|
||||
var scalarReversed [32]byte
|
||||
p256GetScalar(&scalarReversed, scalar)
|
||||
|
||||
var px, py, x1, y1, z1 [p256Limbs]uint32
|
||||
p256FromBig(&px, bigX)
|
||||
p256FromBig(&py, bigY)
|
||||
p256ScalarMult(&x1, &y1, &z1, &px, &py, &scalarReversed)
|
||||
return p256ToAffine(&x1, &y1, &z1)
|
||||
}
|
||||
|
||||
// p256Precomputed contains precomputed values to aid the calculation of scalar
|
||||
// multiples of the base point, G. It's actually two, equal length, tables
|
||||
// concatenated.
|
||||
//
|
||||
// The first table contains (x,y) field element pairs for 16 multiples of the
|
||||
// base point, G.
|
||||
//
|
||||
// Index | Index (binary) | Value
|
||||
// 0 | 0000 | 0G (all zeros, omitted)
|
||||
// 1 | 0001 | G
|
||||
// 2 | 0010 | 2**64G
|
||||
// 3 | 0011 | 2**64G + G
|
||||
// 4 | 0100 | 2**128G
|
||||
// 5 | 0101 | 2**128G + G
|
||||
// 6 | 0110 | 2**128G + 2**64G
|
||||
// 7 | 0111 | 2**128G + 2**64G + G
|
||||
// 8 | 1000 | 2**192G
|
||||
// 9 | 1001 | 2**192G + G
|
||||
// 10 | 1010 | 2**192G + 2**64G
|
||||
// 11 | 1011 | 2**192G + 2**64G + G
|
||||
// 12 | 1100 | 2**192G + 2**128G
|
||||
// 13 | 1101 | 2**192G + 2**128G + G
|
||||
// 14 | 1110 | 2**192G + 2**128G + 2**64G
|
||||
// 15 | 1111 | 2**192G + 2**128G + 2**64G + G
|
||||
//
|
||||
// The second table follows the same style, but the terms are 2**32G,
|
||||
// 2**96G, 2**160G, 2**224G.
|
||||
//
|
||||
// This is ~2KB of data.
|
||||
var p256Precomputed = [p256Limbs * 2 * 15 * 2]uint32{
|
||||
0x11522878, 0xe730d41, 0xdb60179, 0x4afe2ff, 0x12883add, 0xcaddd88, 0x119e7edc, 0xd4a6eab, 0x3120bee,
|
||||
0x1d2aac15, 0xf25357c, 0x19e45cdd, 0x5c721d0, 0x1992c5a5, 0xa237487, 0x154ba21, 0x14b10bb, 0xae3fe3,
|
||||
0xd41a576, 0x922fc51, 0x234994f, 0x60b60d3, 0x164586ae, 0xce95f18, 0x1fe49073, 0x3fa36cc, 0x5ebcd2c,
|
||||
0xb402f2f, 0x15c70bf, 0x1561925c, 0x5a26704, 0xda91e90, 0xcdc1c7f, 0x1ea12446, 0xe1ade1e, 0xec91f22,
|
||||
0x26f7778, 0x566847e, 0xa0bec9e, 0x234f453, 0x1a31f21a, 0xd85e75c, 0x56c7109, 0xa267a00, 0xb57c050,
|
||||
0x98fb57, 0xaa837cc, 0x60c0792, 0xcfa5e19, 0x61bab9e, 0x589e39b, 0xa324c5, 0x7d6dee7, 0x2976e4b,
|
||||
0x1fc4124a, 0xa8c244b, 0x1ce86762, 0xcd61c7e, 0x1831c8e0, 0x75774e1, 0x1d96a5a9, 0x843a649, 0xc3ab0fa,
|
||||
0x6e2e7d5, 0x7673a2a, 0x178b65e8, 0x4003e9b, 0x1a1f11c2, 0x7816ea, 0xf643e11, 0x58c43df, 0xf423fc2,
|
||||
0x19633ffa, 0x891f2b2, 0x123c231c, 0x46add8c, 0x54700dd, 0x59e2b17, 0x172db40f, 0x83e277d, 0xb0dd609,
|
||||
0xfd1da12, 0x35c6e52, 0x19ede20c, 0xd19e0c0, 0x97d0f40, 0xb015b19, 0x449e3f5, 0xe10c9e, 0x33ab581,
|
||||
0x56a67ab, 0x577734d, 0x1dddc062, 0xc57b10d, 0x149b39d, 0x26a9e7b, 0xc35df9f, 0x48764cd, 0x76dbcca,
|
||||
0xca4b366, 0xe9303ab, 0x1a7480e7, 0x57e9e81, 0x1e13eb50, 0xf466cf3, 0x6f16b20, 0x4ba3173, 0xc168c33,
|
||||
0x15cb5439, 0x6a38e11, 0x73658bd, 0xb29564f, 0x3f6dc5b, 0x53b97e, 0x1322c4c0, 0x65dd7ff, 0x3a1e4f6,
|
||||
0x14e614aa, 0x9246317, 0x1bc83aca, 0xad97eed, 0xd38ce4a, 0xf82b006, 0x341f077, 0xa6add89, 0x4894acd,
|
||||
0x9f162d5, 0xf8410ef, 0x1b266a56, 0xd7f223, 0x3e0cb92, 0xe39b672, 0x6a2901a, 0x69a8556, 0x7e7c0,
|
||||
0x9b7d8d3, 0x309a80, 0x1ad05f7f, 0xc2fb5dd, 0xcbfd41d, 0x9ceb638, 0x1051825c, 0xda0cf5b, 0x812e881,
|
||||
0x6f35669, 0x6a56f2c, 0x1df8d184, 0x345820, 0x1477d477, 0x1645db1, 0xbe80c51, 0xc22be3e, 0xe35e65a,
|
||||
0x1aeb7aa0, 0xc375315, 0xf67bc99, 0x7fdd7b9, 0x191fc1be, 0x61235d, 0x2c184e9, 0x1c5a839, 0x47a1e26,
|
||||
0xb7cb456, 0x93e225d, 0x14f3c6ed, 0xccc1ac9, 0x17fe37f3, 0x4988989, 0x1a90c502, 0x2f32042, 0xa17769b,
|
||||
0xafd8c7c, 0x8191c6e, 0x1dcdb237, 0x16200c0, 0x107b32a1, 0x66c08db, 0x10d06a02, 0x3fc93, 0x5620023,
|
||||
0x16722b27, 0x68b5c59, 0x270fcfc, 0xfad0ecc, 0xe5de1c2, 0xeab466b, 0x2fc513c, 0x407f75c, 0xbaab133,
|
||||
0x9705fe9, 0xb88b8e7, 0x734c993, 0x1e1ff8f, 0x19156970, 0xabd0f00, 0x10469ea7, 0x3293ac0, 0xcdc98aa,
|
||||
0x1d843fd, 0xe14bfe8, 0x15be825f, 0x8b5212, 0xeb3fb67, 0x81cbd29, 0xbc62f16, 0x2b6fcc7, 0xf5a4e29,
|
||||
0x13560b66, 0xc0b6ac2, 0x51ae690, 0xd41e271, 0xf3e9bd4, 0x1d70aab, 0x1029f72, 0x73e1c35, 0xee70fbc,
|
||||
0xad81baf, 0x9ecc49a, 0x86c741e, 0xfe6be30, 0x176752e7, 0x23d416, 0x1f83de85, 0x27de188, 0x66f70b8,
|
||||
0x181cd51f, 0x96b6e4c, 0x188f2335, 0xa5df759, 0x17a77eb6, 0xfeb0e73, 0x154ae914, 0x2f3ec51, 0x3826b59,
|
||||
0xb91f17d, 0x1c72949, 0x1362bf0a, 0xe23fddf, 0xa5614b0, 0xf7d8f, 0x79061, 0x823d9d2, 0x8213f39,
|
||||
0x1128ae0b, 0xd095d05, 0xb85c0c2, 0x1ecb2ef, 0x24ddc84, 0xe35e901, 0x18411a4a, 0xf5ddc3d, 0x3786689,
|
||||
0x52260e8, 0x5ae3564, 0x542b10d, 0x8d93a45, 0x19952aa4, 0x996cc41, 0x1051a729, 0x4be3499, 0x52b23aa,
|
||||
0x109f307e, 0x6f5b6bb, 0x1f84e1e7, 0x77a0cfa, 0x10c4df3f, 0x25a02ea, 0xb048035, 0xe31de66, 0xc6ecaa3,
|
||||
0x28ea335, 0x2886024, 0x1372f020, 0xf55d35, 0x15e4684c, 0xf2a9e17, 0x1a4a7529, 0xcb7beb1, 0xb2a78a1,
|
||||
0x1ab21f1f, 0x6361ccf, 0x6c9179d, 0xb135627, 0x1267b974, 0x4408bad, 0x1cbff658, 0xe3d6511, 0xc7d76f,
|
||||
0x1cc7a69, 0xe7ee31b, 0x54fab4f, 0x2b914f, 0x1ad27a30, 0xcd3579e, 0xc50124c, 0x50daa90, 0xb13f72,
|
||||
0xb06aa75, 0x70f5cc6, 0x1649e5aa, 0x84a5312, 0x329043c, 0x41c4011, 0x13d32411, 0xb04a838, 0xd760d2d,
|
||||
0x1713b532, 0xbaa0c03, 0x84022ab, 0x6bcf5c1, 0x2f45379, 0x18ae070, 0x18c9e11e, 0x20bca9a, 0x66f496b,
|
||||
0x3eef294, 0x67500d2, 0xd7f613c, 0x2dbbeb, 0xb741038, 0xe04133f, 0x1582968d, 0xbe985f7, 0x1acbc1a,
|
||||
0x1a6a939f, 0x33e50f6, 0xd665ed4, 0xb4b7bd6, 0x1e5a3799, 0x6b33847, 0x17fa56ff, 0x65ef930, 0x21dc4a,
|
||||
0x2b37659, 0x450fe17, 0xb357b65, 0xdf5efac, 0x15397bef, 0x9d35a7f, 0x112ac15f, 0x624e62e, 0xa90ae2f,
|
||||
0x107eecd2, 0x1f69bbe, 0x77d6bce, 0x5741394, 0x13c684fc, 0x950c910, 0x725522b, 0xdc78583, 0x40eeabb,
|
||||
0x1fde328a, 0xbd61d96, 0xd28c387, 0x9e77d89, 0x12550c40, 0x759cb7d, 0x367ef34, 0xae2a960, 0x91b8bdc,
|
||||
0x93462a9, 0xf469ef, 0xb2e9aef, 0xd2ca771, 0x54e1f42, 0x7aaa49, 0x6316abb, 0x2413c8e, 0x5425bf9,
|
||||
0x1bed3e3a, 0xf272274, 0x1f5e7326, 0x6416517, 0xea27072, 0x9cedea7, 0x6e7633, 0x7c91952, 0xd806dce,
|
||||
0x8e2a7e1, 0xe421e1a, 0x418c9e1, 0x1dbc890, 0x1b395c36, 0xa1dc175, 0x1dc4ef73, 0x8956f34, 0xe4b5cf2,
|
||||
0x1b0d3a18, 0x3194a36, 0x6c2641f, 0xe44124c, 0xa2f4eaa, 0xa8c25ba, 0xf927ed7, 0x627b614, 0x7371cca,
|
||||
0xba16694, 0x417bc03, 0x7c0a7e3, 0x9c35c19, 0x1168a205, 0x8b6b00d, 0x10e3edc9, 0x9c19bf2, 0x5882229,
|
||||
0x1b2b4162, 0xa5cef1a, 0x1543622b, 0x9bd433e, 0x364e04d, 0x7480792, 0x5c9b5b3, 0xe85ff25, 0x408ef57,
|
||||
0x1814cfa4, 0x121b41b, 0xd248a0f, 0x3b05222, 0x39bb16a, 0xc75966d, 0xa038113, 0xa4a1769, 0x11fbc6c,
|
||||
0x917e50e, 0xeec3da8, 0x169d6eac, 0x10c1699, 0xa416153, 0xf724912, 0x15cd60b7, 0x4acbad9, 0x5efc5fa,
|
||||
0xf150ed7, 0x122b51, 0x1104b40a, 0xcb7f442, 0xfbb28ff, 0x6ac53ca, 0x196142cc, 0x7bf0fa9, 0x957651,
|
||||
0x4e0f215, 0xed439f8, 0x3f46bd5, 0x5ace82f, 0x110916b6, 0x6db078, 0xffd7d57, 0xf2ecaac, 0xca86dec,
|
||||
0x15d6b2da, 0x965ecc9, 0x1c92b4c2, 0x1f3811, 0x1cb080f5, 0x2d8b804, 0x19d1c12d, 0xf20bd46, 0x1951fa7,
|
||||
0xa3656c3, 0x523a425, 0xfcd0692, 0xd44ddc8, 0x131f0f5b, 0xaf80e4a, 0xcd9fc74, 0x99bb618, 0x2db944c,
|
||||
0xa673090, 0x1c210e1, 0x178c8d23, 0x1474383, 0x10b8743d, 0x985a55b, 0x2e74779, 0x576138, 0x9587927,
|
||||
0x133130fa, 0xbe05516, 0x9f4d619, 0xbb62570, 0x99ec591, 0xd9468fe, 0x1d07782d, 0xfc72e0b, 0x701b298,
|
||||
0x1863863b, 0x85954b8, 0x121a0c36, 0x9e7fedf, 0xf64b429, 0x9b9d71e, 0x14e2f5d8, 0xf858d3a, 0x942eea8,
|
||||
0xda5b765, 0x6edafff, 0xa9d18cc, 0xc65e4ba, 0x1c747e86, 0xe4ea915, 0x1981d7a1, 0x8395659, 0x52ed4e2,
|
||||
0x87d43b7, 0x37ab11b, 0x19d292ce, 0xf8d4692, 0x18c3053f, 0x8863e13, 0x4c146c0, 0x6bdf55a, 0x4e4457d,
|
||||
0x16152289, 0xac78ec2, 0x1a59c5a2, 0x2028b97, 0x71c2d01, 0x295851f, 0x404747b, 0x878558d, 0x7d29aa4,
|
||||
0x13d8341f, 0x8daefd7, 0x139c972d, 0x6b7ea75, 0xd4a9dde, 0xff163d8, 0x81d55d7, 0xa5bef68, 0xb7b30d8,
|
||||
0xbe73d6f, 0xaa88141, 0xd976c81, 0x7e7a9cc, 0x18beb771, 0xd773cbd, 0x13f51951, 0x9d0c177, 0x1c49a78,
|
||||
}
|
||||
|
||||
// Group operations:
|
||||
//
|
||||
// Elements of the elliptic curve group are represented in Jacobian
|
||||
// coordinates: (x, y, z). An affine point (x', y') is x'=x/z**2, y'=y/z**3 in
|
||||
// Jacobian form.
|
||||
|
||||
// p256PointDouble sets {xOut,yOut,zOut} = 2*{x,y,z}.
|
||||
//
|
||||
// See https://www.hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-0.html#doubling-dbl-2009-l
|
||||
func p256PointDouble(xOut, yOut, zOut, x, y, z *[p256Limbs]uint32) {
|
||||
var delta, gamma, alpha, beta, tmp, tmp2 [p256Limbs]uint32
|
||||
|
||||
p256Square(&delta, z)
|
||||
p256Square(&gamma, y)
|
||||
p256Mul(&beta, x, &gamma)
|
||||
|
||||
p256Sum(&tmp, x, &delta)
|
||||
p256Diff(&tmp2, x, &delta)
|
||||
p256Mul(&alpha, &tmp, &tmp2)
|
||||
p256Scalar3(&alpha)
|
||||
|
||||
p256Sum(&tmp, y, z)
|
||||
p256Square(&tmp, &tmp)
|
||||
p256Diff(&tmp, &tmp, &gamma)
|
||||
p256Diff(zOut, &tmp, &delta)
|
||||
|
||||
p256Scalar4(&beta)
|
||||
p256Square(xOut, &alpha)
|
||||
p256Diff(xOut, xOut, &beta)
|
||||
p256Diff(xOut, xOut, &beta)
|
||||
|
||||
p256Diff(&tmp, &beta, xOut)
|
||||
p256Mul(&tmp, &alpha, &tmp)
|
||||
p256Square(&tmp2, &gamma)
|
||||
p256Scalar8(&tmp2)
|
||||
p256Diff(yOut, &tmp, &tmp2)
|
||||
}
|
||||
|
||||
// p256PointAddMixed sets {xOut,yOut,zOut} = {x1,y1,z1} + {x2,y2,1}.
|
||||
// (i.e. the second point is affine.)
|
||||
//
|
||||
// See https://www.hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-0.html#addition-add-2007-bl
|
||||
//
|
||||
// Note that this function does not handle P+P, infinity+P nor P+infinity
|
||||
// correctly.
|
||||
func p256PointAddMixed(xOut, yOut, zOut, x1, y1, z1, x2, y2 *[p256Limbs]uint32) {
|
||||
var z1z1, z1z1z1, s2, u2, h, i, j, r, rr, v, tmp [p256Limbs]uint32
|
||||
|
||||
p256Square(&z1z1, z1)
|
||||
p256Sum(&tmp, z1, z1)
|
||||
|
||||
p256Mul(&u2, x2, &z1z1)
|
||||
p256Mul(&z1z1z1, z1, &z1z1)
|
||||
p256Mul(&s2, y2, &z1z1z1)
|
||||
p256Diff(&h, &u2, x1)
|
||||
p256Sum(&i, &h, &h)
|
||||
p256Square(&i, &i)
|
||||
p256Mul(&j, &h, &i)
|
||||
p256Diff(&r, &s2, y1)
|
||||
p256Sum(&r, &r, &r)
|
||||
p256Mul(&v, x1, &i)
|
||||
|
||||
p256Mul(zOut, &tmp, &h)
|
||||
p256Square(&rr, &r)
|
||||
p256Diff(xOut, &rr, &j)
|
||||
p256Diff(xOut, xOut, &v)
|
||||
p256Diff(xOut, xOut, &v)
|
||||
|
||||
p256Diff(&tmp, &v, xOut)
|
||||
p256Mul(yOut, &tmp, &r)
|
||||
p256Mul(&tmp, y1, &j)
|
||||
p256Diff(yOut, yOut, &tmp)
|
||||
p256Diff(yOut, yOut, &tmp)
|
||||
}
|
||||
|
||||
// p256PointAdd sets {xOut,yOut,zOut} = {x1,y1,z1} + {x2,y2,z2}.
|
||||
//
|
||||
// See https://www.hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-0.html#addition-add-2007-bl
|
||||
//
|
||||
// Note that this function does not handle P+P, infinity+P nor P+infinity
|
||||
// correctly.
|
||||
func p256PointAdd(xOut, yOut, zOut, x1, y1, z1, x2, y2, z2 *[p256Limbs]uint32) {
|
||||
var z1z1, z1z1z1, z2z2, z2z2z2, s1, s2, u1, u2, h, i, j, r, rr, v, tmp [p256Limbs]uint32
|
||||
|
||||
p256Square(&z1z1, z1)
|
||||
p256Square(&z2z2, z2)
|
||||
p256Mul(&u1, x1, &z2z2)
|
||||
|
||||
p256Sum(&tmp, z1, z2)
|
||||
p256Square(&tmp, &tmp)
|
||||
p256Diff(&tmp, &tmp, &z1z1)
|
||||
p256Diff(&tmp, &tmp, &z2z2)
|
||||
|
||||
p256Mul(&z2z2z2, z2, &z2z2)
|
||||
p256Mul(&s1, y1, &z2z2z2)
|
||||
|
||||
p256Mul(&u2, x2, &z1z1)
|
||||
p256Mul(&z1z1z1, z1, &z1z1)
|
||||
p256Mul(&s2, y2, &z1z1z1)
|
||||
p256Diff(&h, &u2, &u1)
|
||||
p256Sum(&i, &h, &h)
|
||||
p256Square(&i, &i)
|
||||
p256Mul(&j, &h, &i)
|
||||
p256Diff(&r, &s2, &s1)
|
||||
p256Sum(&r, &r, &r)
|
||||
p256Mul(&v, &u1, &i)
|
||||
|
||||
p256Mul(zOut, &tmp, &h)
|
||||
p256Square(&rr, &r)
|
||||
p256Diff(xOut, &rr, &j)
|
||||
p256Diff(xOut, xOut, &v)
|
||||
p256Diff(xOut, xOut, &v)
|
||||
|
||||
p256Diff(&tmp, &v, xOut)
|
||||
p256Mul(yOut, &tmp, &r)
|
||||
p256Mul(&tmp, &s1, &j)
|
||||
p256Diff(yOut, yOut, &tmp)
|
||||
p256Diff(yOut, yOut, &tmp)
|
||||
}
|
||||
|
||||
// p256SelectAffinePoint sets {out_x,out_y} to the index'th entry of table.
|
||||
//
|
||||
// On entry: index < 16, table[0] must be zero.
|
||||
func p256SelectAffinePoint(xOut, yOut *[p256Limbs]uint32, table []uint32, index uint32) {
|
||||
for i := range xOut {
|
||||
xOut[i] = 0
|
||||
}
|
||||
for i := range yOut {
|
||||
yOut[i] = 0
|
||||
}
|
||||
|
||||
for i := uint32(1); i < 16; i++ {
|
||||
mask := i ^ index
|
||||
mask |= mask >> 2
|
||||
mask |= mask >> 1
|
||||
mask &= 1
|
||||
mask--
|
||||
for j := range xOut {
|
||||
xOut[j] |= table[0] & mask
|
||||
table = table[1:]
|
||||
}
|
||||
for j := range yOut {
|
||||
yOut[j] |= table[0] & mask
|
||||
table = table[1:]
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// p256SelectJacobianPoint sets {out_x,out_y,out_z} to the index'th entry of
|
||||
// table.
|
||||
//
|
||||
// On entry: index < 16, table[0] must be zero.
|
||||
func p256SelectJacobianPoint(xOut, yOut, zOut *[p256Limbs]uint32, table *[16][3][p256Limbs]uint32, index uint32) {
|
||||
for i := range xOut {
|
||||
xOut[i] = 0
|
||||
}
|
||||
for i := range yOut {
|
||||
yOut[i] = 0
|
||||
}
|
||||
for i := range zOut {
|
||||
zOut[i] = 0
|
||||
}
|
||||
|
||||
// The implicit value at index 0 is all zero. We don't need to perform that
|
||||
// iteration of the loop because we already set out_* to zero.
|
||||
for i := uint32(1); i < 16; i++ {
|
||||
mask := i ^ index
|
||||
mask |= mask >> 2
|
||||
mask |= mask >> 1
|
||||
mask &= 1
|
||||
mask--
|
||||
for j := range xOut {
|
||||
xOut[j] |= table[i][0][j] & mask
|
||||
}
|
||||
for j := range yOut {
|
||||
yOut[j] |= table[i][1][j] & mask
|
||||
}
|
||||
for j := range zOut {
|
||||
zOut[j] |= table[i][2][j] & mask
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// p256GetBit returns the bit'th bit of scalar.
|
||||
func p256GetBit(scalar *[32]uint8, bit uint) uint32 {
|
||||
return uint32(((scalar[bit>>3]) >> (bit & 7)) & 1)
|
||||
}
|
||||
|
||||
// p256ScalarBaseMult sets {xOut,yOut,zOut} = scalar*G where scalar is a
|
||||
// little-endian number. Note that the value of scalar must be less than the
|
||||
// order of the group.
|
||||
func p256ScalarBaseMult(xOut, yOut, zOut *[p256Limbs]uint32, scalar *[32]uint8) {
|
||||
nIsInfinityMask := ^uint32(0)
|
||||
var pIsNoninfiniteMask, mask, tableOffset uint32
|
||||
var px, py, tx, ty, tz [p256Limbs]uint32
|
||||
|
||||
for i := range xOut {
|
||||
xOut[i] = 0
|
||||
}
|
||||
for i := range yOut {
|
||||
yOut[i] = 0
|
||||
}
|
||||
for i := range zOut {
|
||||
zOut[i] = 0
|
||||
}
|
||||
|
||||
// The loop adds bits at positions 0, 64, 128 and 192, followed by
|
||||
// positions 32,96,160 and 224 and does this 32 times.
|
||||
for i := uint(0); i < 32; i++ {
|
||||
if i != 0 {
|
||||
p256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
|
||||
}
|
||||
tableOffset = 0
|
||||
for j := uint(0); j <= 32; j += 32 {
|
||||
bit0 := p256GetBit(scalar, 31-i+j)
|
||||
bit1 := p256GetBit(scalar, 95-i+j)
|
||||
bit2 := p256GetBit(scalar, 159-i+j)
|
||||
bit3 := p256GetBit(scalar, 223-i+j)
|
||||
index := bit0 | (bit1 << 1) | (bit2 << 2) | (bit3 << 3)
|
||||
|
||||
p256SelectAffinePoint(&px, &py, p256Precomputed[tableOffset:], index)
|
||||
tableOffset += 30 * p256Limbs
|
||||
|
||||
// Since scalar is less than the order of the group, we know that
|
||||
// {xOut,yOut,zOut} != {px,py,1}, unless both are zero, which we handle
|
||||
// below.
|
||||
p256PointAddMixed(&tx, &ty, &tz, xOut, yOut, zOut, &px, &py)
|
||||
// The result of pointAddMixed is incorrect if {xOut,yOut,zOut} is zero
|
||||
// (a.k.a. the point at infinity). We handle that situation by
|
||||
// copying the point from the table.
|
||||
p256CopyConditional(xOut, &px, nIsInfinityMask)
|
||||
p256CopyConditional(yOut, &py, nIsInfinityMask)
|
||||
p256CopyConditional(zOut, &p256One, nIsInfinityMask)
|
||||
|
||||
// Equally, the result is also wrong if the point from the table is
|
||||
// zero, which happens when the index is zero. We handle that by
|
||||
// only copying from {tx,ty,tz} to {xOut,yOut,zOut} if index != 0.
|
||||
pIsNoninfiniteMask = nonZeroToAllOnes(index)
|
||||
mask = pIsNoninfiniteMask & ^nIsInfinityMask
|
||||
p256CopyConditional(xOut, &tx, mask)
|
||||
p256CopyConditional(yOut, &ty, mask)
|
||||
p256CopyConditional(zOut, &tz, mask)
|
||||
// If p was not zero, then n is now non-zero.
|
||||
nIsInfinityMask &^= pIsNoninfiniteMask
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// p256PointToAffine converts a Jacobian point to an affine point. If the input
|
||||
// is the point at infinity then it returns (0, 0) in constant time.
|
||||
func p256PointToAffine(xOut, yOut, x, y, z *[p256Limbs]uint32) {
|
||||
var zInv, zInvSq [p256Limbs]uint32
|
||||
|
||||
p256Invert(&zInv, z)
|
||||
p256Square(&zInvSq, &zInv)
|
||||
p256Mul(xOut, x, &zInvSq)
|
||||
p256Mul(&zInv, &zInv, &zInvSq)
|
||||
p256Mul(yOut, y, &zInv)
|
||||
}
|
||||
|
||||
// p256ToAffine returns a pair of *big.Int containing the affine representation
|
||||
// of {x,y,z}.
|
||||
func p256ToAffine(x, y, z *[p256Limbs]uint32) (xOut, yOut *big.Int) {
|
||||
var xx, yy [p256Limbs]uint32
|
||||
p256PointToAffine(&xx, &yy, x, y, z)
|
||||
return p256ToBig(&xx), p256ToBig(&yy)
|
||||
}
|
||||
|
||||
// p256ScalarMult sets {xOut,yOut,zOut} = scalar*{x,y}.
|
||||
func p256ScalarMult(xOut, yOut, zOut, x, y *[p256Limbs]uint32, scalar *[32]uint8) {
|
||||
var px, py, pz, tx, ty, tz [p256Limbs]uint32
|
||||
var precomp [16][3][p256Limbs]uint32
|
||||
var nIsInfinityMask, index, pIsNoninfiniteMask, mask uint32
|
||||
|
||||
// We precompute 0,1,2,... times {x,y}.
|
||||
precomp[1][0] = *x
|
||||
precomp[1][1] = *y
|
||||
precomp[1][2] = p256One
|
||||
|
||||
for i := 2; i < 16; i += 2 {
|
||||
p256PointDouble(&precomp[i][0], &precomp[i][1], &precomp[i][2], &precomp[i/2][0], &precomp[i/2][1], &precomp[i/2][2])
|
||||
p256PointAddMixed(&precomp[i+1][0], &precomp[i+1][1], &precomp[i+1][2], &precomp[i][0], &precomp[i][1], &precomp[i][2], x, y)
|
||||
}
|
||||
|
||||
for i := range xOut {
|
||||
xOut[i] = 0
|
||||
}
|
||||
for i := range yOut {
|
||||
yOut[i] = 0
|
||||
}
|
||||
for i := range zOut {
|
||||
zOut[i] = 0
|
||||
}
|
||||
nIsInfinityMask = ^uint32(0)
|
||||
|
||||
// We add in a window of four bits each iteration and do this 64 times.
|
||||
for i := 0; i < 64; i++ {
|
||||
if i != 0 {
|
||||
p256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
|
||||
p256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
|
||||
p256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
|
||||
p256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
|
||||
}
|
||||
|
||||
index = uint32(scalar[31-i/2])
|
||||
if (i & 1) == 1 {
|
||||
index &= 15
|
||||
} else {
|
||||
index >>= 4
|
||||
}
|
||||
|
||||
// See the comments in scalarBaseMult about handling infinities.
|
||||
p256SelectJacobianPoint(&px, &py, &pz, &precomp, index)
|
||||
p256PointAdd(&tx, &ty, &tz, xOut, yOut, zOut, &px, &py, &pz)
|
||||
p256CopyConditional(xOut, &px, nIsInfinityMask)
|
||||
p256CopyConditional(yOut, &py, nIsInfinityMask)
|
||||
p256CopyConditional(zOut, &pz, nIsInfinityMask)
|
||||
|
||||
pIsNoninfiniteMask = nonZeroToAllOnes(index)
|
||||
mask = pIsNoninfiniteMask & ^nIsInfinityMask
|
||||
p256CopyConditional(xOut, &tx, mask)
|
||||
p256CopyConditional(yOut, &ty, mask)
|
||||
p256CopyConditional(zOut, &tz, mask)
|
||||
nIsInfinityMask &^= pIsNoninfiniteMask
|
||||
}
|
||||
}
|
||||
|
|
@ -1,705 +0,0 @@
|
|||
// Copyright 2013 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
//go:build !amd64 && !arm64
|
||||
|
||||
package elliptic
|
||||
|
||||
import "math/big"
|
||||
|
||||
// Field elements are represented as nine, unsigned 32-bit words.
|
||||
//
|
||||
// The value of a field element is:
|
||||
// x[0] + (x[1] * 2**29) + (x[2] * 2**57) + ... + (x[8] * 2**228)
|
||||
//
|
||||
// That is, each limb is alternately 29 or 28-bits wide in little-endian
|
||||
// order.
|
||||
//
|
||||
// This means that a field element hits 2**257, rather than 2**256 as we would
|
||||
// like. A 28, 29, ... pattern would cause us to hit 2**256, but that causes
|
||||
// problems when multiplying as terms end up one bit short of a limb which
|
||||
// would require much bit-shifting to correct.
|
||||
//
|
||||
// Finally, the values stored in a field element are in Montgomery form. So the
|
||||
// value |y| is stored as (y*R) mod p, where p is the P-256 prime and R is
|
||||
// 2**257.
|
||||
|
||||
const (
|
||||
p256Limbs = 9
|
||||
bottom29Bits = 0x1fffffff
|
||||
)
|
||||
|
||||
var (
|
||||
// p256One is the number 1 as a field element.
|
||||
p256One = [p256Limbs]uint32{2, 0, 0, 0xffff800, 0x1fffffff, 0xfffffff, 0x1fbfffff, 0x1ffffff, 0}
|
||||
p256Zero = [p256Limbs]uint32{0, 0, 0, 0, 0, 0, 0, 0, 0}
|
||||
// p256P is the prime modulus as a field element.
|
||||
p256P = [p256Limbs]uint32{0x1fffffff, 0xfffffff, 0x1fffffff, 0x3ff, 0, 0, 0x200000, 0xf000000, 0xfffffff}
|
||||
// p2562P is the twice prime modulus as a field element.
|
||||
p2562P = [p256Limbs]uint32{0x1ffffffe, 0xfffffff, 0x1fffffff, 0x7ff, 0, 0, 0x400000, 0xe000000, 0x1fffffff}
|
||||
)
|
||||
|
||||
// Field element operations:
|
||||
|
||||
const bottom28Bits = 0xfffffff
|
||||
|
||||
// nonZeroToAllOnes returns:
|
||||
//
|
||||
// 0xffffffff for 0 < x <= 2**31
|
||||
// 0 for x == 0 or x > 2**31.
|
||||
func nonZeroToAllOnes(x uint32) uint32 {
|
||||
return ((x - 1) >> 31) - 1
|
||||
}
|
||||
|
||||
// p256ReduceCarry adds a multiple of p in order to cancel |carry|,
|
||||
// which is a term at 2**257.
|
||||
//
|
||||
// On entry: carry < 2**3, inout[0,2,...] < 2**29, inout[1,3,...] < 2**28.
|
||||
// On exit: inout[0,2,..] < 2**30, inout[1,3,...] < 2**29.
|
||||
func p256ReduceCarry(inout *[p256Limbs]uint32, carry uint32) {
|
||||
carry_mask := nonZeroToAllOnes(carry)
|
||||
|
||||
inout[0] += carry << 1
|
||||
inout[3] += 0x10000000 & carry_mask
|
||||
// carry < 2**3 thus (carry << 11) < 2**14 and we added 2**28 in the
|
||||
// previous line therefore this doesn't underflow.
|
||||
inout[3] -= carry << 11
|
||||
inout[4] += (0x20000000 - 1) & carry_mask
|
||||
inout[5] += (0x10000000 - 1) & carry_mask
|
||||
inout[6] += (0x20000000 - 1) & carry_mask
|
||||
inout[6] -= carry << 22
|
||||
// This may underflow if carry is non-zero but, if so, we'll fix it in the
|
||||
// next line.
|
||||
inout[7] -= 1 & carry_mask
|
||||
inout[7] += carry << 25
|
||||
}
|
||||
|
||||
// p256Sum sets out = in+in2.
|
||||
//
|
||||
// On entry: in[i]+in2[i] must not overflow a 32-bit word.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Sum(out, in, in2 *[p256Limbs]uint32) {
|
||||
carry := uint32(0)
|
||||
for i := 0; ; i++ {
|
||||
out[i] = in[i] + in2[i]
|
||||
out[i] += carry
|
||||
carry = out[i] >> 29
|
||||
out[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
if i == p256Limbs {
|
||||
break
|
||||
}
|
||||
|
||||
out[i] = in[i] + in2[i]
|
||||
out[i] += carry
|
||||
carry = out[i] >> 28
|
||||
out[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
p256ReduceCarry(out, carry)
|
||||
}
|
||||
|
||||
const (
|
||||
two30m2 = 1<<30 - 1<<2
|
||||
two30p13m2 = 1<<30 + 1<<13 - 1<<2
|
||||
two31m2 = 1<<31 - 1<<2
|
||||
two31m3 = 1<<31 - 1<<3
|
||||
two31p24m2 = 1<<31 + 1<<24 - 1<<2
|
||||
two30m27m2 = 1<<30 - 1<<27 - 1<<2
|
||||
)
|
||||
|
||||
// p256Zero31 is 0 mod p.
|
||||
var p256Zero31 = [p256Limbs]uint32{two31m3, two30m2, two31m2, two30p13m2, two31m2, two30m2, two31p24m2, two30m27m2, two31m2}
|
||||
|
||||
// p256Diff sets out = in-in2.
|
||||
//
|
||||
// On entry: in[0,2,...] < 2**30, in[1,3,...] < 2**29 and
|
||||
// in2[0,2,...] < 2**30, in2[1,3,...] < 2**29.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Diff(out, in, in2 *[p256Limbs]uint32) {
|
||||
var carry uint32
|
||||
|
||||
for i := 0; ; i++ {
|
||||
out[i] = in[i] - in2[i]
|
||||
out[i] += p256Zero31[i]
|
||||
out[i] += carry
|
||||
carry = out[i] >> 29
|
||||
out[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
if i == p256Limbs {
|
||||
break
|
||||
}
|
||||
|
||||
out[i] = in[i] - in2[i]
|
||||
out[i] += p256Zero31[i]
|
||||
out[i] += carry
|
||||
carry = out[i] >> 28
|
||||
out[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
p256ReduceCarry(out, carry)
|
||||
}
|
||||
|
||||
// p256ReduceDegree sets out = tmp/R mod p where tmp contains 64-bit words with
|
||||
// the same 29,28,... bit positions as a field element.
|
||||
//
|
||||
// The values in field elements are in Montgomery form: x*R mod p where R =
|
||||
// 2**257. Since we just multiplied two Montgomery values together, the result
|
||||
// is x*y*R*R mod p. We wish to divide by R in order for the result also to be
|
||||
// in Montgomery form.
|
||||
//
|
||||
// On entry: tmp[i] < 2**64.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256ReduceDegree(out *[p256Limbs]uint32, tmp [17]uint64) {
|
||||
// The following table may be helpful when reading this code:
|
||||
//
|
||||
// Limb number: 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10...
|
||||
// Width (bits): 29| 28| 29| 28| 29| 28| 29| 28| 29| 28| 29
|
||||
// Start bit: 0 | 29| 57| 86|114|143|171|200|228|257|285
|
||||
// (odd phase): 0 | 28| 57| 85|114|142|171|199|228|256|285
|
||||
var tmp2 [18]uint32
|
||||
var carry, x, xMask uint32
|
||||
|
||||
// tmp contains 64-bit words with the same 29,28,29-bit positions as a
|
||||
// field element. So the top of an element of tmp might overlap with
|
||||
// another element two positions down. The following loop eliminates
|
||||
// this overlap.
|
||||
tmp2[0] = uint32(tmp[0]) & bottom29Bits
|
||||
|
||||
tmp2[1] = uint32(tmp[0]) >> 29
|
||||
tmp2[1] |= (uint32(tmp[0]>>32) << 3) & bottom28Bits
|
||||
tmp2[1] += uint32(tmp[1]) & bottom28Bits
|
||||
carry = tmp2[1] >> 28
|
||||
tmp2[1] &= bottom28Bits
|
||||
|
||||
for i := 2; i < 17; i++ {
|
||||
tmp2[i] = (uint32(tmp[i-2] >> 32)) >> 25
|
||||
tmp2[i] += (uint32(tmp[i-1])) >> 28
|
||||
tmp2[i] += (uint32(tmp[i-1]>>32) << 4) & bottom29Bits
|
||||
tmp2[i] += uint32(tmp[i]) & bottom29Bits
|
||||
tmp2[i] += carry
|
||||
carry = tmp2[i] >> 29
|
||||
tmp2[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
if i == 17 {
|
||||
break
|
||||
}
|
||||
tmp2[i] = uint32(tmp[i-2]>>32) >> 25
|
||||
tmp2[i] += uint32(tmp[i-1]) >> 29
|
||||
tmp2[i] += ((uint32(tmp[i-1] >> 32)) << 3) & bottom28Bits
|
||||
tmp2[i] += uint32(tmp[i]) & bottom28Bits
|
||||
tmp2[i] += carry
|
||||
carry = tmp2[i] >> 28
|
||||
tmp2[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
tmp2[17] = uint32(tmp[15]>>32) >> 25
|
||||
tmp2[17] += uint32(tmp[16]) >> 29
|
||||
tmp2[17] += uint32(tmp[16]>>32) << 3
|
||||
tmp2[17] += carry
|
||||
|
||||
// Montgomery elimination of terms:
|
||||
//
|
||||
// Since R is 2**257, we can divide by R with a bitwise shift if we can
|
||||
// ensure that the right-most 257 bits are all zero. We can make that true
|
||||
// by adding multiplies of p without affecting the value.
|
||||
//
|
||||
// So we eliminate limbs from right to left. Since the bottom 29 bits of p
|
||||
// are all ones, then by adding tmp2[0]*p to tmp2 we'll make tmp2[0] == 0.
|
||||
// We can do that for 8 further limbs and then right shift to eliminate the
|
||||
// extra factor of R.
|
||||
for i := 0; ; i += 2 {
|
||||
tmp2[i+1] += tmp2[i] >> 29
|
||||
x = tmp2[i] & bottom29Bits
|
||||
xMask = nonZeroToAllOnes(x)
|
||||
tmp2[i] = 0
|
||||
|
||||
// The bounds calculations for this loop are tricky. Each iteration of
|
||||
// the loop eliminates two words by adding values to words to their
|
||||
// right.
|
||||
//
|
||||
// The following table contains the amounts added to each word (as an
|
||||
// offset from the value of i at the top of the loop). The amounts are
|
||||
// accounted for from the first and second half of the loop separately
|
||||
// and are written as, for example, 28 to mean a value <2**28.
|
||||
//
|
||||
// Word: 3 4 5 6 7 8 9 10
|
||||
// Added in top half: 28 11 29 21 29 28
|
||||
// 28 29
|
||||
// 29
|
||||
// Added in bottom half: 29 10 28 21 28 28
|
||||
// 29
|
||||
//
|
||||
// The value that is currently offset 7 will be offset 5 for the next
|
||||
// iteration and then offset 3 for the iteration after that. Therefore
|
||||
// the total value added will be the values added at 7, 5 and 3.
|
||||
//
|
||||
// The following table accumulates these values. The sums at the bottom
|
||||
// are written as, for example, 29+28, to mean a value < 2**29+2**28.
|
||||
//
|
||||
// Word: 3 4 5 6 7 8 9 10 11 12 13
|
||||
// 28 11 10 29 21 29 28 28 28 28 28
|
||||
// 29 28 11 28 29 28 29 28 29 28
|
||||
// 29 28 21 21 29 21 29 21
|
||||
// 10 29 28 21 28 21 28
|
||||
// 28 29 28 29 28 29 28
|
||||
// 11 10 29 10 29 10
|
||||
// 29 28 11 28 11
|
||||
// 29 29
|
||||
// --------------------------------------------
|
||||
// 30+ 31+ 30+ 31+ 30+
|
||||
// 28+ 29+ 28+ 29+ 21+
|
||||
// 21+ 28+ 21+ 28+ 10
|
||||
// 10 21+ 10 21+
|
||||
// 11 11
|
||||
//
|
||||
// So the greatest amount is added to tmp2[10] and tmp2[12]. If
|
||||
// tmp2[10/12] has an initial value of <2**29, then the maximum value
|
||||
// will be < 2**31 + 2**30 + 2**28 + 2**21 + 2**11, which is < 2**32,
|
||||
// as required.
|
||||
tmp2[i+3] += (x << 10) & bottom28Bits
|
||||
tmp2[i+4] += (x >> 18)
|
||||
|
||||
tmp2[i+6] += (x << 21) & bottom29Bits
|
||||
tmp2[i+7] += x >> 8
|
||||
|
||||
// At position 200, which is the starting bit position for word 7, we
|
||||
// have a factor of 0xf000000 = 2**28 - 2**24.
|
||||
tmp2[i+7] += 0x10000000 & xMask
|
||||
tmp2[i+8] += (x - 1) & xMask
|
||||
tmp2[i+7] -= (x << 24) & bottom28Bits
|
||||
tmp2[i+8] -= x >> 4
|
||||
|
||||
tmp2[i+8] += 0x20000000 & xMask
|
||||
tmp2[i+8] -= x
|
||||
tmp2[i+8] += (x << 28) & bottom29Bits
|
||||
tmp2[i+9] += ((x >> 1) - 1) & xMask
|
||||
|
||||
if i+1 == p256Limbs {
|
||||
break
|
||||
}
|
||||
tmp2[i+2] += tmp2[i+1] >> 28
|
||||
x = tmp2[i+1] & bottom28Bits
|
||||
xMask = nonZeroToAllOnes(x)
|
||||
tmp2[i+1] = 0
|
||||
|
||||
tmp2[i+4] += (x << 11) & bottom29Bits
|
||||
tmp2[i+5] += (x >> 18)
|
||||
|
||||
tmp2[i+7] += (x << 21) & bottom28Bits
|
||||
tmp2[i+8] += x >> 7
|
||||
|
||||
// At position 199, which is the starting bit of the 8th word when
|
||||
// dealing with a context starting on an odd word, we have a factor of
|
||||
// 0x1e000000 = 2**29 - 2**25. Since we have not updated i, the 8th
|
||||
// word from i+1 is i+8.
|
||||
tmp2[i+8] += 0x20000000 & xMask
|
||||
tmp2[i+9] += (x - 1) & xMask
|
||||
tmp2[i+8] -= (x << 25) & bottom29Bits
|
||||
tmp2[i+9] -= x >> 4
|
||||
|
||||
tmp2[i+9] += 0x10000000 & xMask
|
||||
tmp2[i+9] -= x
|
||||
tmp2[i+10] += (x - 1) & xMask
|
||||
}
|
||||
|
||||
// We merge the right shift with a carry chain. The words above 2**257 have
|
||||
// widths of 28,29,... which we need to correct when copying them down.
|
||||
carry = 0
|
||||
for i := 0; i < 8; i++ {
|
||||
// The maximum value of tmp2[i + 9] occurs on the first iteration and
|
||||
// is < 2**30+2**29+2**28. Adding 2**29 (from tmp2[i + 10]) is
|
||||
// therefore safe.
|
||||
out[i] = tmp2[i+9]
|
||||
out[i] += carry
|
||||
out[i] += (tmp2[i+10] << 28) & bottom29Bits
|
||||
carry = out[i] >> 29
|
||||
out[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
out[i] = tmp2[i+9] >> 1
|
||||
out[i] += carry
|
||||
carry = out[i] >> 28
|
||||
out[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
out[8] = tmp2[17]
|
||||
out[8] += carry
|
||||
carry = out[8] >> 29
|
||||
out[8] &= bottom29Bits
|
||||
|
||||
p256ReduceCarry(out, carry)
|
||||
}
|
||||
|
||||
// p256Square sets out=in*in.
|
||||
//
|
||||
// On entry: in[0,2,...] < 2**30, in[1,3,...] < 2**29.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Square(out, in *[p256Limbs]uint32) {
|
||||
var tmp [17]uint64
|
||||
|
||||
tmp[0] = uint64(in[0]) * uint64(in[0])
|
||||
tmp[1] = uint64(in[0]) * (uint64(in[1]) << 1)
|
||||
tmp[2] = uint64(in[0])*(uint64(in[2])<<1) +
|
||||
uint64(in[1])*(uint64(in[1])<<1)
|
||||
tmp[3] = uint64(in[0])*(uint64(in[3])<<1) +
|
||||
uint64(in[1])*(uint64(in[2])<<1)
|
||||
tmp[4] = uint64(in[0])*(uint64(in[4])<<1) +
|
||||
uint64(in[1])*(uint64(in[3])<<2) +
|
||||
uint64(in[2])*uint64(in[2])
|
||||
tmp[5] = uint64(in[0])*(uint64(in[5])<<1) +
|
||||
uint64(in[1])*(uint64(in[4])<<1) +
|
||||
uint64(in[2])*(uint64(in[3])<<1)
|
||||
tmp[6] = uint64(in[0])*(uint64(in[6])<<1) +
|
||||
uint64(in[1])*(uint64(in[5])<<2) +
|
||||
uint64(in[2])*(uint64(in[4])<<1) +
|
||||
uint64(in[3])*(uint64(in[3])<<1)
|
||||
tmp[7] = uint64(in[0])*(uint64(in[7])<<1) +
|
||||
uint64(in[1])*(uint64(in[6])<<1) +
|
||||
uint64(in[2])*(uint64(in[5])<<1) +
|
||||
uint64(in[3])*(uint64(in[4])<<1)
|
||||
// tmp[8] has the greatest value of 2**61 + 2**60 + 2**61 + 2**60 + 2**60,
|
||||
// which is < 2**64 as required.
|
||||
tmp[8] = uint64(in[0])*(uint64(in[8])<<1) +
|
||||
uint64(in[1])*(uint64(in[7])<<2) +
|
||||
uint64(in[2])*(uint64(in[6])<<1) +
|
||||
uint64(in[3])*(uint64(in[5])<<2) +
|
||||
uint64(in[4])*uint64(in[4])
|
||||
tmp[9] = uint64(in[1])*(uint64(in[8])<<1) +
|
||||
uint64(in[2])*(uint64(in[7])<<1) +
|
||||
uint64(in[3])*(uint64(in[6])<<1) +
|
||||
uint64(in[4])*(uint64(in[5])<<1)
|
||||
tmp[10] = uint64(in[2])*(uint64(in[8])<<1) +
|
||||
uint64(in[3])*(uint64(in[7])<<2) +
|
||||
uint64(in[4])*(uint64(in[6])<<1) +
|
||||
uint64(in[5])*(uint64(in[5])<<1)
|
||||
tmp[11] = uint64(in[3])*(uint64(in[8])<<1) +
|
||||
uint64(in[4])*(uint64(in[7])<<1) +
|
||||
uint64(in[5])*(uint64(in[6])<<1)
|
||||
tmp[12] = uint64(in[4])*(uint64(in[8])<<1) +
|
||||
uint64(in[5])*(uint64(in[7])<<2) +
|
||||
uint64(in[6])*uint64(in[6])
|
||||
tmp[13] = uint64(in[5])*(uint64(in[8])<<1) +
|
||||
uint64(in[6])*(uint64(in[7])<<1)
|
||||
tmp[14] = uint64(in[6])*(uint64(in[8])<<1) +
|
||||
uint64(in[7])*(uint64(in[7])<<1)
|
||||
tmp[15] = uint64(in[7]) * (uint64(in[8]) << 1)
|
||||
tmp[16] = uint64(in[8]) * uint64(in[8])
|
||||
|
||||
p256ReduceDegree(out, tmp)
|
||||
}
|
||||
|
||||
// p256Mul sets out=in*in2.
|
||||
//
|
||||
// On entry: in[0,2,...] < 2**30, in[1,3,...] < 2**29 and
|
||||
// in2[0,2,...] < 2**30, in2[1,3,...] < 2**29.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Mul(out, in, in2 *[p256Limbs]uint32) {
|
||||
var tmp [17]uint64
|
||||
|
||||
tmp[0] = uint64(in[0]) * uint64(in2[0])
|
||||
tmp[1] = uint64(in[0])*(uint64(in2[1])<<0) +
|
||||
uint64(in[1])*(uint64(in2[0])<<0)
|
||||
tmp[2] = uint64(in[0])*(uint64(in2[2])<<0) +
|
||||
uint64(in[1])*(uint64(in2[1])<<1) +
|
||||
uint64(in[2])*(uint64(in2[0])<<0)
|
||||
tmp[3] = uint64(in[0])*(uint64(in2[3])<<0) +
|
||||
uint64(in[1])*(uint64(in2[2])<<0) +
|
||||
uint64(in[2])*(uint64(in2[1])<<0) +
|
||||
uint64(in[3])*(uint64(in2[0])<<0)
|
||||
tmp[4] = uint64(in[0])*(uint64(in2[4])<<0) +
|
||||
uint64(in[1])*(uint64(in2[3])<<1) +
|
||||
uint64(in[2])*(uint64(in2[2])<<0) +
|
||||
uint64(in[3])*(uint64(in2[1])<<1) +
|
||||
uint64(in[4])*(uint64(in2[0])<<0)
|
||||
tmp[5] = uint64(in[0])*(uint64(in2[5])<<0) +
|
||||
uint64(in[1])*(uint64(in2[4])<<0) +
|
||||
uint64(in[2])*(uint64(in2[3])<<0) +
|
||||
uint64(in[3])*(uint64(in2[2])<<0) +
|
||||
uint64(in[4])*(uint64(in2[1])<<0) +
|
||||
uint64(in[5])*(uint64(in2[0])<<0)
|
||||
tmp[6] = uint64(in[0])*(uint64(in2[6])<<0) +
|
||||
uint64(in[1])*(uint64(in2[5])<<1) +
|
||||
uint64(in[2])*(uint64(in2[4])<<0) +
|
||||
uint64(in[3])*(uint64(in2[3])<<1) +
|
||||
uint64(in[4])*(uint64(in2[2])<<0) +
|
||||
uint64(in[5])*(uint64(in2[1])<<1) +
|
||||
uint64(in[6])*(uint64(in2[0])<<0)
|
||||
tmp[7] = uint64(in[0])*(uint64(in2[7])<<0) +
|
||||
uint64(in[1])*(uint64(in2[6])<<0) +
|
||||
uint64(in[2])*(uint64(in2[5])<<0) +
|
||||
uint64(in[3])*(uint64(in2[4])<<0) +
|
||||
uint64(in[4])*(uint64(in2[3])<<0) +
|
||||
uint64(in[5])*(uint64(in2[2])<<0) +
|
||||
uint64(in[6])*(uint64(in2[1])<<0) +
|
||||
uint64(in[7])*(uint64(in2[0])<<0)
|
||||
// tmp[8] has the greatest value but doesn't overflow. See logic in
|
||||
// p256Square.
|
||||
tmp[8] = uint64(in[0])*(uint64(in2[8])<<0) +
|
||||
uint64(in[1])*(uint64(in2[7])<<1) +
|
||||
uint64(in[2])*(uint64(in2[6])<<0) +
|
||||
uint64(in[3])*(uint64(in2[5])<<1) +
|
||||
uint64(in[4])*(uint64(in2[4])<<0) +
|
||||
uint64(in[5])*(uint64(in2[3])<<1) +
|
||||
uint64(in[6])*(uint64(in2[2])<<0) +
|
||||
uint64(in[7])*(uint64(in2[1])<<1) +
|
||||
uint64(in[8])*(uint64(in2[0])<<0)
|
||||
tmp[9] = uint64(in[1])*(uint64(in2[8])<<0) +
|
||||
uint64(in[2])*(uint64(in2[7])<<0) +
|
||||
uint64(in[3])*(uint64(in2[6])<<0) +
|
||||
uint64(in[4])*(uint64(in2[5])<<0) +
|
||||
uint64(in[5])*(uint64(in2[4])<<0) +
|
||||
uint64(in[6])*(uint64(in2[3])<<0) +
|
||||
uint64(in[7])*(uint64(in2[2])<<0) +
|
||||
uint64(in[8])*(uint64(in2[1])<<0)
|
||||
tmp[10] = uint64(in[2])*(uint64(in2[8])<<0) +
|
||||
uint64(in[3])*(uint64(in2[7])<<1) +
|
||||
uint64(in[4])*(uint64(in2[6])<<0) +
|
||||
uint64(in[5])*(uint64(in2[5])<<1) +
|
||||
uint64(in[6])*(uint64(in2[4])<<0) +
|
||||
uint64(in[7])*(uint64(in2[3])<<1) +
|
||||
uint64(in[8])*(uint64(in2[2])<<0)
|
||||
tmp[11] = uint64(in[3])*(uint64(in2[8])<<0) +
|
||||
uint64(in[4])*(uint64(in2[7])<<0) +
|
||||
uint64(in[5])*(uint64(in2[6])<<0) +
|
||||
uint64(in[6])*(uint64(in2[5])<<0) +
|
||||
uint64(in[7])*(uint64(in2[4])<<0) +
|
||||
uint64(in[8])*(uint64(in2[3])<<0)
|
||||
tmp[12] = uint64(in[4])*(uint64(in2[8])<<0) +
|
||||
uint64(in[5])*(uint64(in2[7])<<1) +
|
||||
uint64(in[6])*(uint64(in2[6])<<0) +
|
||||
uint64(in[7])*(uint64(in2[5])<<1) +
|
||||
uint64(in[8])*(uint64(in2[4])<<0)
|
||||
tmp[13] = uint64(in[5])*(uint64(in2[8])<<0) +
|
||||
uint64(in[6])*(uint64(in2[7])<<0) +
|
||||
uint64(in[7])*(uint64(in2[6])<<0) +
|
||||
uint64(in[8])*(uint64(in2[5])<<0)
|
||||
tmp[14] = uint64(in[6])*(uint64(in2[8])<<0) +
|
||||
uint64(in[7])*(uint64(in2[7])<<1) +
|
||||
uint64(in[8])*(uint64(in2[6])<<0)
|
||||
tmp[15] = uint64(in[7])*(uint64(in2[8])<<0) +
|
||||
uint64(in[8])*(uint64(in2[7])<<0)
|
||||
tmp[16] = uint64(in[8]) * (uint64(in2[8]) << 0)
|
||||
|
||||
p256ReduceDegree(out, tmp)
|
||||
}
|
||||
|
||||
func p256Assign(out, in *[p256Limbs]uint32) {
|
||||
*out = *in
|
||||
}
|
||||
|
||||
// p256Invert calculates |out| = |in|^{-1}
|
||||
//
|
||||
// Based on Fermat's Little Theorem:
|
||||
//
|
||||
// a^p = a (mod p)
|
||||
// a^{p-1} = 1 (mod p)
|
||||
// a^{p-2} = a^{-1} (mod p)
|
||||
func p256Invert(out, in *[p256Limbs]uint32) {
|
||||
var ftmp, ftmp2 [p256Limbs]uint32
|
||||
|
||||
// each e_I will hold |in|^{2^I - 1}
|
||||
var e2, e4, e8, e16, e32, e64 [p256Limbs]uint32
|
||||
|
||||
p256Square(&ftmp, in) // 2^1
|
||||
p256Mul(&ftmp, in, &ftmp) // 2^2 - 2^0
|
||||
p256Assign(&e2, &ftmp)
|
||||
p256Square(&ftmp, &ftmp) // 2^3 - 2^1
|
||||
p256Square(&ftmp, &ftmp) // 2^4 - 2^2
|
||||
p256Mul(&ftmp, &ftmp, &e2) // 2^4 - 2^0
|
||||
p256Assign(&e4, &ftmp)
|
||||
p256Square(&ftmp, &ftmp) // 2^5 - 2^1
|
||||
p256Square(&ftmp, &ftmp) // 2^6 - 2^2
|
||||
p256Square(&ftmp, &ftmp) // 2^7 - 2^3
|
||||
p256Square(&ftmp, &ftmp) // 2^8 - 2^4
|
||||
p256Mul(&ftmp, &ftmp, &e4) // 2^8 - 2^0
|
||||
p256Assign(&e8, &ftmp)
|
||||
for i := 0; i < 8; i++ {
|
||||
p256Square(&ftmp, &ftmp)
|
||||
} // 2^16 - 2^8
|
||||
p256Mul(&ftmp, &ftmp, &e8) // 2^16 - 2^0
|
||||
p256Assign(&e16, &ftmp)
|
||||
for i := 0; i < 16; i++ {
|
||||
p256Square(&ftmp, &ftmp)
|
||||
} // 2^32 - 2^16
|
||||
p256Mul(&ftmp, &ftmp, &e16) // 2^32 - 2^0
|
||||
p256Assign(&e32, &ftmp)
|
||||
for i := 0; i < 32; i++ {
|
||||
p256Square(&ftmp, &ftmp)
|
||||
} // 2^64 - 2^32
|
||||
p256Assign(&e64, &ftmp)
|
||||
p256Mul(&ftmp, &ftmp, in) // 2^64 - 2^32 + 2^0
|
||||
for i := 0; i < 192; i++ {
|
||||
p256Square(&ftmp, &ftmp)
|
||||
} // 2^256 - 2^224 + 2^192
|
||||
|
||||
p256Mul(&ftmp2, &e64, &e32) // 2^64 - 2^0
|
||||
for i := 0; i < 16; i++ {
|
||||
p256Square(&ftmp2, &ftmp2)
|
||||
} // 2^80 - 2^16
|
||||
p256Mul(&ftmp2, &ftmp2, &e16) // 2^80 - 2^0
|
||||
for i := 0; i < 8; i++ {
|
||||
p256Square(&ftmp2, &ftmp2)
|
||||
} // 2^88 - 2^8
|
||||
p256Mul(&ftmp2, &ftmp2, &e8) // 2^88 - 2^0
|
||||
for i := 0; i < 4; i++ {
|
||||
p256Square(&ftmp2, &ftmp2)
|
||||
} // 2^92 - 2^4
|
||||
p256Mul(&ftmp2, &ftmp2, &e4) // 2^92 - 2^0
|
||||
p256Square(&ftmp2, &ftmp2) // 2^93 - 2^1
|
||||
p256Square(&ftmp2, &ftmp2) // 2^94 - 2^2
|
||||
p256Mul(&ftmp2, &ftmp2, &e2) // 2^94 - 2^0
|
||||
p256Square(&ftmp2, &ftmp2) // 2^95 - 2^1
|
||||
p256Square(&ftmp2, &ftmp2) // 2^96 - 2^2
|
||||
p256Mul(&ftmp2, &ftmp2, in) // 2^96 - 3
|
||||
|
||||
p256Mul(out, &ftmp2, &ftmp) // 2^256 - 2^224 + 2^192 + 2^96 - 3
|
||||
}
|
||||
|
||||
// p256Scalar3 sets out=3*out.
|
||||
//
|
||||
// On entry: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Scalar3(out *[p256Limbs]uint32) {
|
||||
var carry uint32
|
||||
|
||||
for i := 0; ; i++ {
|
||||
out[i] *= 3
|
||||
out[i] += carry
|
||||
carry = out[i] >> 29
|
||||
out[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
if i == p256Limbs {
|
||||
break
|
||||
}
|
||||
|
||||
out[i] *= 3
|
||||
out[i] += carry
|
||||
carry = out[i] >> 28
|
||||
out[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
p256ReduceCarry(out, carry)
|
||||
}
|
||||
|
||||
// p256Scalar4 sets out=4*out.
|
||||
//
|
||||
// On entry: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Scalar4(out *[p256Limbs]uint32) {
|
||||
var carry, nextCarry uint32
|
||||
|
||||
for i := 0; ; i++ {
|
||||
nextCarry = out[i] >> 27
|
||||
out[i] <<= 2
|
||||
out[i] &= bottom29Bits
|
||||
out[i] += carry
|
||||
carry = nextCarry + (out[i] >> 29)
|
||||
out[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
if i == p256Limbs {
|
||||
break
|
||||
}
|
||||
nextCarry = out[i] >> 26
|
||||
out[i] <<= 2
|
||||
out[i] &= bottom28Bits
|
||||
out[i] += carry
|
||||
carry = nextCarry + (out[i] >> 28)
|
||||
out[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
p256ReduceCarry(out, carry)
|
||||
}
|
||||
|
||||
// p256Scalar8 sets out=8*out.
|
||||
//
|
||||
// On entry: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
// On exit: out[0,2,...] < 2**30, out[1,3,...] < 2**29.
|
||||
func p256Scalar8(out *[p256Limbs]uint32) {
|
||||
var carry, nextCarry uint32
|
||||
|
||||
for i := 0; ; i++ {
|
||||
nextCarry = out[i] >> 26
|
||||
out[i] <<= 3
|
||||
out[i] &= bottom29Bits
|
||||
out[i] += carry
|
||||
carry = nextCarry + (out[i] >> 29)
|
||||
out[i] &= bottom29Bits
|
||||
|
||||
i++
|
||||
if i == p256Limbs {
|
||||
break
|
||||
}
|
||||
nextCarry = out[i] >> 25
|
||||
out[i] <<= 3
|
||||
out[i] &= bottom28Bits
|
||||
out[i] += carry
|
||||
carry = nextCarry + (out[i] >> 28)
|
||||
out[i] &= bottom28Bits
|
||||
}
|
||||
|
||||
p256ReduceCarry(out, carry)
|
||||
}
|
||||
|
||||
// p256CopyConditional sets out=in if mask = 0xffffffff in constant time.
|
||||
//
|
||||
// On entry: mask is either 0 or 0xffffffff.
|
||||
func p256CopyConditional(out, in *[p256Limbs]uint32, mask uint32) {
|
||||
for i := 0; i < p256Limbs; i++ {
|
||||
tmp := mask & (in[i] ^ out[i])
|
||||
out[i] ^= tmp
|
||||
}
|
||||
}
|
||||
|
||||
// p256FromBig sets out = R*in.
|
||||
func p256FromBig(out *[p256Limbs]uint32, in *big.Int) {
|
||||
tmp := new(big.Int).Lsh(in, 257)
|
||||
tmp.Mod(tmp, p256Params.P)
|
||||
|
||||
for i := 0; i < p256Limbs; i++ {
|
||||
if bits := tmp.Bits(); len(bits) > 0 {
|
||||
out[i] = uint32(bits[0]) & bottom29Bits
|
||||
} else {
|
||||
out[i] = 0
|
||||
}
|
||||
tmp.Rsh(tmp, 29)
|
||||
|
||||
i++
|
||||
if i == p256Limbs {
|
||||
break
|
||||
}
|
||||
|
||||
if bits := tmp.Bits(); len(bits) > 0 {
|
||||
out[i] = uint32(bits[0]) & bottom28Bits
|
||||
} else {
|
||||
out[i] = 0
|
||||
}
|
||||
tmp.Rsh(tmp, 28)
|
||||
}
|
||||
}
|
||||
|
||||
// p256ToBig returns a *big.Int containing the value of in.
|
||||
func p256ToBig(in *[p256Limbs]uint32) *big.Int {
|
||||
result, tmp := new(big.Int), new(big.Int)
|
||||
|
||||
result.SetInt64(int64(in[p256Limbs-1]))
|
||||
for i := p256Limbs - 2; i >= 0; i-- {
|
||||
if (i & 1) == 0 {
|
||||
result.Lsh(result, 29)
|
||||
} else {
|
||||
result.Lsh(result, 28)
|
||||
}
|
||||
tmp.SetInt64(int64(in[i]))
|
||||
result.Add(result, tmp)
|
||||
}
|
||||
|
||||
result.Mul(result, p256RInverse)
|
||||
result.Mod(result, p256Params.P)
|
||||
return result
|
||||
}
|
||||
|
|
@ -1,15 +0,0 @@
|
|||
// Copyright 2016 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
//go:build !amd64 && !s390x && !arm64 && !ppc64le
|
||||
// +build !amd64,!s390x,!arm64,!ppc64le
|
||||
|
||||
package elliptic
|
||||
|
||||
var p256 p256Curve
|
||||
|
||||
func initP256Arch() {
|
||||
// Use pure Go constant-time implementation.
|
||||
p256 = p256Curve{p256Params}
|
||||
}
|
||||
|
|
@ -27,14 +27,13 @@ type p256Point struct {
|
|||
z [32]byte
|
||||
}
|
||||
|
||||
var (
|
||||
p256 Curve
|
||||
p256PreFast *[37][64]p256Point
|
||||
)
|
||||
var p256PreFast *[37][64]p256Point
|
||||
|
||||
func initP256Arch() {
|
||||
p256 = p256CurveFast{p256Params}
|
||||
initTable()
|
||||
func init() {
|
||||
initP256Arch = func() {
|
||||
p256 = p256CurveFast{&p256Params}
|
||||
initTable()
|
||||
}
|
||||
}
|
||||
|
||||
func (curve p256CurveFast) Params() *CurveParams {
|
||||
|
|
|
|||
|
|
@ -28,10 +28,7 @@ type p256Point struct {
|
|||
z [32]byte
|
||||
}
|
||||
|
||||
var (
|
||||
p256 Curve
|
||||
p256PreFast *[37][64]p256Point
|
||||
)
|
||||
var p256PreFast *[37][64]p256Point
|
||||
|
||||
//go:noescape
|
||||
func p256MulInternalTrampolineSetup()
|
||||
|
|
@ -51,15 +48,13 @@ func p256SqrInternalVX()
|
|||
//go:noescape
|
||||
func p256SqrInternalVMSL()
|
||||
|
||||
func initP256Arch() {
|
||||
func init() {
|
||||
if cpu.S390X.HasVX {
|
||||
p256 = p256CurveFast{p256Params}
|
||||
initTable()
|
||||
return
|
||||
initP256Arch = func() {
|
||||
p256 = p256CurveFast{&p256Params}
|
||||
initTable()
|
||||
}
|
||||
}
|
||||
|
||||
// No vector support, use pure Go implementation.
|
||||
p256 = p256Curve{p256Params}
|
||||
}
|
||||
|
||||
func (curve p256CurveFast) Params() *CurveParams {
|
||||
|
|
|
|||
Loading…
Reference in New Issue