mirror of
https://github.com/42wim/matterbridge.git
synced 2024-11-25 04:02:03 -08:00
241 lines
5.1 KiB
Go
241 lines
5.1 KiB
Go
// 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 */
|
|
}
|