f18bd55240
We expect the table to have a slightly nested structure, so just generate it that way. Avoid risking strict aliasing problems. Thanks to Brian Smith for pointing this out. Change-Id: Ie21610c4afab07a610d914265079135dba17b3b7 Reviewed-on: https://boringssl-review.googlesource.com/c/34264 Commit-Queue: Adam Langley <agl@google.com> Reviewed-by: Adam Langley <agl@google.com>
131 lines
4.0 KiB
Go
131 lines
4.0 KiB
Go
/* Copyright (c) 2018, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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package main
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import (
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"crypto/elliptic"
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"fmt"
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"math/big"
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"os"
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)
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const fileHeader = `/* Copyright (c) 2015, Intel Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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// This is the precomputed constant time access table for the code in
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// p256-x86_64.c, for the default generator. The table consists of 37
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// subtables, each subtable contains 64 affine points. The affine points are
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// encoded as eight uint64's, four for the x coordinate and four for the y.
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// Both values are in little-endian order. There are 37 tables because a
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// signed, 6-bit wNAF form of the scalar is used and ceil(256/(6 + 1)) = 37.
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// Within each table there are 64 values because the 6-bit wNAF value can take
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// 64 values, ignoring the sign bit, which is implemented by performing a
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// negation of the affine point when required. We would like to align it to 2MB
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// in order to increase the chances of using a large page but that appears to
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// lead to invalid ELF files being produced.
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// This file is generated by make_p256-x86_64-table.go.
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static const alignas(4096) PRECOMP256_ROW ecp_nistz256_precomputed[37] = {
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`
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func main() {
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os.Stdout.WriteString(fileHeader)
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scalar, tmp := new(big.Int), new(big.Int)
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p256 := elliptic.P256()
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p := p256.Params().P
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// The wNAF windows are 7 bits wide, so advance across the 256-bit scalar
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// space in 7-bit increments.
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for shift := uint(0); shift < 256; shift += 7 {
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// For each window, encode 64 multiples of the base point.
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for multiple := 1; multiple <= 64; multiple++ {
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scalar.SetInt64(int64(multiple))
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scalar.Lsh(scalar, shift)
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x, y := p256.ScalarBaseMult(scalar.Bytes())
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toMontgomery(x, p)
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toMontgomery(y, p)
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if multiple == 1 {
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os.Stdout.WriteString(" {{")
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} else {
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os.Stdout.WriteString(" {")
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}
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printNum(x, tmp)
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os.Stdout.WriteString(",\n ")
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printNum(y, tmp)
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if multiple == 64 {
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os.Stdout.WriteString("}}")
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} else {
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os.Stdout.WriteString("},\n")
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}
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}
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if shift+7 < 256 {
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os.Stdout.WriteString(",\n")
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} else {
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os.Stdout.WriteString("};\n")
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}
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}
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}
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var mask, R *big.Int
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func init() {
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mask = new(big.Int).SetUint64(0xffffffffffffffff)
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R = new(big.Int).SetInt64(1)
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R.Lsh(R, 256)
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}
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func printNum(n, tmp *big.Int) {
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fmt.Printf("{")
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for i := 0; i < 4; i++ {
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tmp.And(n, mask)
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limb := tmp.Uint64()
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fmt.Printf("TOBN(0x%08x, 0x%08x)", uint32(limb>>32), uint32(limb))
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n.Rsh(n, 64)
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switch i {
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case 0, 2:
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os.Stdout.WriteString(", ")
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case 1:
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os.Stdout.WriteString(",\n ")
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}
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}
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fmt.Printf("}")
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}
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// toMontgomery sets n to be n×R mod p
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func toMontgomery(n, p *big.Int) {
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n.Mul(n, R)
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n.Mod(n, p)
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}
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