+++ /dev/null
-// Copyright 2012 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.
-
-// +build amd64,!gccgo,!appengine
-
-package curve25519
-
-// These functions are implemented in the .s files. The names of the functions
-// in the rest of the file are also taken from the SUPERCOP sources to help
-// people following along.
-
-//go:noescape
-
-func cswap(inout *[5]uint64, v uint64)
-
-//go:noescape
-
-func ladderstep(inout *[5][5]uint64)
-
-//go:noescape
-
-func freeze(inout *[5]uint64)
-
-//go:noescape
-
-func mul(dest, a, b *[5]uint64)
-
-//go:noescape
-
-func square(out, in *[5]uint64)
-
-// mladder uses a Montgomery ladder to calculate (xr/zr) *= s.
-func mladder(xr, zr *[5]uint64, s *[32]byte) {
- var work [5][5]uint64
-
- work[0] = *xr
- setint(&work[1], 1)
- setint(&work[2], 0)
- work[3] = *xr
- setint(&work[4], 1)
-
- j := uint(6)
- var prevbit byte
-
- for i := 31; i >= 0; i-- {
- for j < 8 {
- bit := ((*s)[i] >> j) & 1
- swap := bit ^ prevbit
- prevbit = bit
- cswap(&work[1], uint64(swap))
- ladderstep(&work)
- j--
- }
- j = 7
- }
-
- *xr = work[1]
- *zr = work[2]
-}
-
-func scalarMult(out, in, base *[32]byte) {
- var e [32]byte
- copy(e[:], (*in)[:])
- e[0] &= 248
- e[31] &= 127
- e[31] |= 64
-
- var t, z [5]uint64
- unpack(&t, base)
- mladder(&t, &z, &e)
- invert(&z, &z)
- mul(&t, &t, &z)
- pack(out, &t)
-}
-
-func setint(r *[5]uint64, v uint64) {
- r[0] = v
- r[1] = 0
- r[2] = 0
- r[3] = 0
- r[4] = 0
-}
-
-// unpack sets r = x where r consists of 5, 51-bit limbs in little-endian
-// order.
-func unpack(r *[5]uint64, x *[32]byte) {
- r[0] = uint64(x[0]) |
- uint64(x[1])<<8 |
- uint64(x[2])<<16 |
- uint64(x[3])<<24 |
- uint64(x[4])<<32 |
- uint64(x[5])<<40 |
- uint64(x[6]&7)<<48
-
- r[1] = uint64(x[6])>>3 |
- uint64(x[7])<<5 |
- uint64(x[8])<<13 |
- uint64(x[9])<<21 |
- uint64(x[10])<<29 |
- uint64(x[11])<<37 |
- uint64(x[12]&63)<<45
-
- r[2] = uint64(x[12])>>6 |
- uint64(x[13])<<2 |
- uint64(x[14])<<10 |
- uint64(x[15])<<18 |
- uint64(x[16])<<26 |
- uint64(x[17])<<34 |
- uint64(x[18])<<42 |
- uint64(x[19]&1)<<50
-
- r[3] = uint64(x[19])>>1 |
- uint64(x[20])<<7 |
- uint64(x[21])<<15 |
- uint64(x[22])<<23 |
- uint64(x[23])<<31 |
- uint64(x[24])<<39 |
- uint64(x[25]&15)<<47
-
- r[4] = uint64(x[25])>>4 |
- uint64(x[26])<<4 |
- uint64(x[27])<<12 |
- uint64(x[28])<<20 |
- uint64(x[29])<<28 |
- uint64(x[30])<<36 |
- uint64(x[31]&127)<<44
-}
-
-// pack sets out = x where out is the usual, little-endian form of the 5,
-// 51-bit limbs in x.
-func pack(out *[32]byte, x *[5]uint64) {
- t := *x
- freeze(&t)
-
- out[0] = byte(t[0])
- out[1] = byte(t[0] >> 8)
- out[2] = byte(t[0] >> 16)
- out[3] = byte(t[0] >> 24)
- out[4] = byte(t[0] >> 32)
- out[5] = byte(t[0] >> 40)
- out[6] = byte(t[0] >> 48)
-
- out[6] ^= byte(t[1]<<3) & 0xf8
- out[7] = byte(t[1] >> 5)
- out[8] = byte(t[1] >> 13)
- out[9] = byte(t[1] >> 21)
- out[10] = byte(t[1] >> 29)
- out[11] = byte(t[1] >> 37)
- out[12] = byte(t[1] >> 45)
-
- out[12] ^= byte(t[2]<<6) & 0xc0
- out[13] = byte(t[2] >> 2)
- out[14] = byte(t[2] >> 10)
- out[15] = byte(t[2] >> 18)
- out[16] = byte(t[2] >> 26)
- out[17] = byte(t[2] >> 34)
- out[18] = byte(t[2] >> 42)
- out[19] = byte(t[2] >> 50)
-
- out[19] ^= byte(t[3]<<1) & 0xfe
- out[20] = byte(t[3] >> 7)
- out[21] = byte(t[3] >> 15)
- out[22] = byte(t[3] >> 23)
- out[23] = byte(t[3] >> 31)
- out[24] = byte(t[3] >> 39)
- out[25] = byte(t[3] >> 47)
-
- out[25] ^= byte(t[4]<<4) & 0xf0
- out[26] = byte(t[4] >> 4)
- out[27] = byte(t[4] >> 12)
- out[28] = byte(t[4] >> 20)
- out[29] = byte(t[4] >> 28)
- out[30] = byte(t[4] >> 36)
- out[31] = byte(t[4] >> 44)
-}
-
-// invert calculates r = x^-1 mod p using Fermat's little theorem.
-func invert(r *[5]uint64, x *[5]uint64) {
- var z2, z9, z11, z2_5_0, z2_10_0, z2_20_0, z2_50_0, z2_100_0, t [5]uint64
-
- square(&z2, x) /* 2 */
- square(&t, &z2) /* 4 */
- square(&t, &t) /* 8 */
- mul(&z9, &t, x) /* 9 */
- mul(&z11, &z9, &z2) /* 11 */
- square(&t, &z11) /* 22 */
- mul(&z2_5_0, &t, &z9) /* 2^5 - 2^0 = 31 */
-
- square(&t, &z2_5_0) /* 2^6 - 2^1 */
- for i := 1; i < 5; i++ { /* 2^20 - 2^10 */
- square(&t, &t)
- }
- mul(&z2_10_0, &t, &z2_5_0) /* 2^10 - 2^0 */
-
- square(&t, &z2_10_0) /* 2^11 - 2^1 */
- for i := 1; i < 10; i++ { /* 2^20 - 2^10 */
- square(&t, &t)
- }
- mul(&z2_20_0, &t, &z2_10_0) /* 2^20 - 2^0 */
-
- square(&t, &z2_20_0) /* 2^21 - 2^1 */
- for i := 1; i < 20; i++ { /* 2^40 - 2^20 */
- square(&t, &t)
- }
- mul(&t, &t, &z2_20_0) /* 2^40 - 2^0 */
-
- square(&t, &t) /* 2^41 - 2^1 */
- for i := 1; i < 10; i++ { /* 2^50 - 2^10 */
- square(&t, &t)
- }
- mul(&z2_50_0, &t, &z2_10_0) /* 2^50 - 2^0 */
-
- square(&t, &z2_50_0) /* 2^51 - 2^1 */
- for i := 1; i < 50; i++ { /* 2^100 - 2^50 */
- square(&t, &t)
- }
- mul(&z2_100_0, &t, &z2_50_0) /* 2^100 - 2^0 */
-
- square(&t, &z2_100_0) /* 2^101 - 2^1 */
- for i := 1; i < 100; i++ { /* 2^200 - 2^100 */
- square(&t, &t)
- }
- mul(&t, &t, &z2_100_0) /* 2^200 - 2^0 */
-
- square(&t, &t) /* 2^201 - 2^1 */
- for i := 1; i < 50; i++ { /* 2^250 - 2^50 */
- square(&t, &t)
- }
- mul(&t, &t, &z2_50_0) /* 2^250 - 2^0 */
-
- square(&t, &t) /* 2^251 - 2^1 */
- square(&t, &t) /* 2^252 - 2^2 */
- square(&t, &t) /* 2^253 - 2^3 */
-
- square(&t, &t) /* 2^254 - 2^4 */
-
- square(&t, &t) /* 2^255 - 2^5 */
- mul(r, &t, &z11) /* 2^255 - 21 */
-}
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