--- /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 appengine gccgo
+
+package salsa
+
+const rounds = 20
+
+// core applies the Salsa20 core function to 16-byte input in, 32-byte key k,
+// and 16-byte constant c, and puts the result into 64-byte array out.
+func core(out *[64]byte, in *[16]byte, k *[32]byte, c *[16]byte) {
+ j0 := uint32(c[0]) | uint32(c[1])<<8 | uint32(c[2])<<16 | uint32(c[3])<<24
+ j1 := uint32(k[0]) | uint32(k[1])<<8 | uint32(k[2])<<16 | uint32(k[3])<<24
+ j2 := uint32(k[4]) | uint32(k[5])<<8 | uint32(k[6])<<16 | uint32(k[7])<<24
+ j3 := uint32(k[8]) | uint32(k[9])<<8 | uint32(k[10])<<16 | uint32(k[11])<<24
+ j4 := uint32(k[12]) | uint32(k[13])<<8 | uint32(k[14])<<16 | uint32(k[15])<<24
+ j5 := uint32(c[4]) | uint32(c[5])<<8 | uint32(c[6])<<16 | uint32(c[7])<<24
+ j6 := uint32(in[0]) | uint32(in[1])<<8 | uint32(in[2])<<16 | uint32(in[3])<<24
+ j7 := uint32(in[4]) | uint32(in[5])<<8 | uint32(in[6])<<16 | uint32(in[7])<<24
+ j8 := uint32(in[8]) | uint32(in[9])<<8 | uint32(in[10])<<16 | uint32(in[11])<<24
+ j9 := uint32(in[12]) | uint32(in[13])<<8 | uint32(in[14])<<16 | uint32(in[15])<<24
+ j10 := uint32(c[8]) | uint32(c[9])<<8 | uint32(c[10])<<16 | uint32(c[11])<<24
+ j11 := uint32(k[16]) | uint32(k[17])<<8 | uint32(k[18])<<16 | uint32(k[19])<<24
+ j12 := uint32(k[20]) | uint32(k[21])<<8 | uint32(k[22])<<16 | uint32(k[23])<<24
+ j13 := uint32(k[24]) | uint32(k[25])<<8 | uint32(k[26])<<16 | uint32(k[27])<<24
+ j14 := uint32(k[28]) | uint32(k[29])<<8 | uint32(k[30])<<16 | uint32(k[31])<<24
+ j15 := uint32(c[12]) | uint32(c[13])<<8 | uint32(c[14])<<16 | uint32(c[15])<<24
+
+ x0, x1, x2, x3, x4, x5, x6, x7, x8 := j0, j1, j2, j3, j4, j5, j6, j7, j8
+ x9, x10, x11, x12, x13, x14, x15 := j9, j10, j11, j12, j13, j14, j15
+
+ for i := 0; i < rounds; i += 2 {
+ u := x0 + x12
+ x4 ^= u<<7 | u>>(32-7)
+ u = x4 + x0
+ x8 ^= u<<9 | u>>(32-9)
+ u = x8 + x4
+ x12 ^= u<<13 | u>>(32-13)
+ u = x12 + x8
+ x0 ^= u<<18 | u>>(32-18)
+
+ u = x5 + x1
+ x9 ^= u<<7 | u>>(32-7)
+ u = x9 + x5
+ x13 ^= u<<9 | u>>(32-9)
+ u = x13 + x9
+ x1 ^= u<<13 | u>>(32-13)
+ u = x1 + x13
+ x5 ^= u<<18 | u>>(32-18)
+
+ u = x10 + x6
+ x14 ^= u<<7 | u>>(32-7)
+ u = x14 + x10
+ x2 ^= u<<9 | u>>(32-9)
+ u = x2 + x14
+ x6 ^= u<<13 | u>>(32-13)
+ u = x6 + x2
+ x10 ^= u<<18 | u>>(32-18)
+
+ u = x15 + x11
+ x3 ^= u<<7 | u>>(32-7)
+ u = x3 + x15
+ x7 ^= u<<9 | u>>(32-9)
+ u = x7 + x3
+ x11 ^= u<<13 | u>>(32-13)
+ u = x11 + x7
+ x15 ^= u<<18 | u>>(32-18)
+
+ u = x0 + x3
+ x1 ^= u<<7 | u>>(32-7)
+ u = x1 + x0
+ x2 ^= u<<9 | u>>(32-9)
+ u = x2 + x1
+ x3 ^= u<<13 | u>>(32-13)
+ u = x3 + x2
+ x0 ^= u<<18 | u>>(32-18)
+
+ u = x5 + x4
+ x6 ^= u<<7 | u>>(32-7)
+ u = x6 + x5
+ x7 ^= u<<9 | u>>(32-9)
+ u = x7 + x6
+ x4 ^= u<<13 | u>>(32-13)
+ u = x4 + x7
+ x5 ^= u<<18 | u>>(32-18)
+
+ u = x10 + x9
+ x11 ^= u<<7 | u>>(32-7)
+ u = x11 + x10
+ x8 ^= u<<9 | u>>(32-9)
+ u = x8 + x11
+ x9 ^= u<<13 | u>>(32-13)
+ u = x9 + x8
+ x10 ^= u<<18 | u>>(32-18)
+
+ u = x15 + x14
+ x12 ^= u<<7 | u>>(32-7)
+ u = x12 + x15
+ x13 ^= u<<9 | u>>(32-9)
+ u = x13 + x12
+ x14 ^= u<<13 | u>>(32-13)
+ u = x14 + x13
+ x15 ^= u<<18 | u>>(32-18)
+ }
+ x0 += j0
+ x1 += j1
+ x2 += j2
+ x3 += j3
+ x4 += j4
+ x5 += j5
+ x6 += j6
+ x7 += j7
+ x8 += j8
+ x9 += j9
+ x10 += j10
+ x11 += j11
+ x12 += j12
+ x13 += j13
+ x14 += j14
+ x15 += j15
+
+ out[0] = byte(x0)
+ out[1] = byte(x0 >> 8)
+ out[2] = byte(x0 >> 16)
+ out[3] = byte(x0 >> 24)
+
+ out[4] = byte(x1)
+ out[5] = byte(x1 >> 8)
+ out[6] = byte(x1 >> 16)
+ out[7] = byte(x1 >> 24)
+
+ out[8] = byte(x2)
+ out[9] = byte(x2 >> 8)
+ out[10] = byte(x2 >> 16)
+ out[11] = byte(x2 >> 24)
+
+ out[12] = byte(x3)
+ out[13] = byte(x3 >> 8)
+ out[14] = byte(x3 >> 16)
+ out[15] = byte(x3 >> 24)
+
+ out[16] = byte(x4)
+ out[17] = byte(x4 >> 8)
+ out[18] = byte(x4 >> 16)
+ out[19] = byte(x4 >> 24)
+
+ out[20] = byte(x5)
+ out[21] = byte(x5 >> 8)
+ out[22] = byte(x5 >> 16)
+ out[23] = byte(x5 >> 24)
+
+ out[24] = byte(x6)
+ out[25] = byte(x6 >> 8)
+ out[26] = byte(x6 >> 16)
+ out[27] = byte(x6 >> 24)
+
+ out[28] = byte(x7)
+ out[29] = byte(x7 >> 8)
+ out[30] = byte(x7 >> 16)
+ out[31] = byte(x7 >> 24)
+
+ out[32] = byte(x8)
+ out[33] = byte(x8 >> 8)
+ out[34] = byte(x8 >> 16)
+ out[35] = byte(x8 >> 24)
+
+ out[36] = byte(x9)
+ out[37] = byte(x9 >> 8)
+ out[38] = byte(x9 >> 16)
+ out[39] = byte(x9 >> 24)
+
+ out[40] = byte(x10)
+ out[41] = byte(x10 >> 8)
+ out[42] = byte(x10 >> 16)
+ out[43] = byte(x10 >> 24)
+
+ out[44] = byte(x11)
+ out[45] = byte(x11 >> 8)
+ out[46] = byte(x11 >> 16)
+ out[47] = byte(x11 >> 24)
+
+ out[48] = byte(x12)
+ out[49] = byte(x12 >> 8)
+ out[50] = byte(x12 >> 16)
+ out[51] = byte(x12 >> 24)
+
+ out[52] = byte(x13)
+ out[53] = byte(x13 >> 8)
+ out[54] = byte(x13 >> 16)
+ out[55] = byte(x13 >> 24)
+
+ out[56] = byte(x14)
+ out[57] = byte(x14 >> 8)
+ out[58] = byte(x14 >> 16)
+ out[59] = byte(x14 >> 24)
+
+ out[60] = byte(x15)
+ out[61] = byte(x15 >> 8)
+ out[62] = byte(x15 >> 16)
+ out[63] = byte(x15 >> 24)
+}
+
+// XORKeyStream crypts bytes from in to out using the given key and counters.
+// In and out may be the same slice but otherwise should not overlap. Counter
+// contains the raw salsa20 counter bytes (both nonce and block counter).
+func XORKeyStream(out, in []byte, counter *[16]byte, key *[32]byte) {
+ var block [64]byte
+ var counterCopy [16]byte
+ copy(counterCopy[:], counter[:])
+
+ for len(in) >= 64 {
+ core(&block, &counterCopy, key, &Sigma)
+ for i, x := range block {
+ out[i] = in[i] ^ x
+ }
+ u := uint32(1)
+ for i := 8; i < 16; i++ {
+ u += uint32(counterCopy[i])
+ counterCopy[i] = byte(u)
+ u >>= 8
+ }
+ in = in[64:]
+ out = out[64:]
+ }
+
+ if len(in) > 0 {
+ core(&block, &counterCopy, key, &Sigma)
+ for i, v := range in {
+ out[i] = v ^ block[i]
+ }
+ }
+}
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