--- /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.
+
+// Package salsa provides low-level access to functions in the Salsa family.
+package salsa // import "golang.org/x/crypto/salsa20/salsa"
+
+// Sigma is the Salsa20 constant for 256-bit keys.
+var Sigma = [16]byte{'e', 'x', 'p', 'a', 'n', 'd', ' ', '3', '2', '-', 'b', 'y', 't', 'e', ' ', 'k'}
+
+// HSalsa20 applies the HSalsa20 core function to a 16-byte input in, 32-byte
+// key k, and 16-byte constant c, and puts the result into the 32-byte array
+// out.
+func HSalsa20(out *[32]byte, in *[16]byte, k *[32]byte, c *[16]byte) {
+ x0 := uint32(c[0]) | uint32(c[1])<<8 | uint32(c[2])<<16 | uint32(c[3])<<24
+ x1 := uint32(k[0]) | uint32(k[1])<<8 | uint32(k[2])<<16 | uint32(k[3])<<24
+ x2 := uint32(k[4]) | uint32(k[5])<<8 | uint32(k[6])<<16 | uint32(k[7])<<24
+ x3 := uint32(k[8]) | uint32(k[9])<<8 | uint32(k[10])<<16 | uint32(k[11])<<24
+ x4 := uint32(k[12]) | uint32(k[13])<<8 | uint32(k[14])<<16 | uint32(k[15])<<24
+ x5 := uint32(c[4]) | uint32(c[5])<<8 | uint32(c[6])<<16 | uint32(c[7])<<24
+ x6 := uint32(in[0]) | uint32(in[1])<<8 | uint32(in[2])<<16 | uint32(in[3])<<24
+ x7 := uint32(in[4]) | uint32(in[5])<<8 | uint32(in[6])<<16 | uint32(in[7])<<24
+ x8 := uint32(in[8]) | uint32(in[9])<<8 | uint32(in[10])<<16 | uint32(in[11])<<24
+ x9 := uint32(in[12]) | uint32(in[13])<<8 | uint32(in[14])<<16 | uint32(in[15])<<24
+ x10 := uint32(c[8]) | uint32(c[9])<<8 | uint32(c[10])<<16 | uint32(c[11])<<24
+ x11 := uint32(k[16]) | uint32(k[17])<<8 | uint32(k[18])<<16 | uint32(k[19])<<24
+ x12 := uint32(k[20]) | uint32(k[21])<<8 | uint32(k[22])<<16 | uint32(k[23])<<24
+ x13 := uint32(k[24]) | uint32(k[25])<<8 | uint32(k[26])<<16 | uint32(k[27])<<24
+ x14 := uint32(k[28]) | uint32(k[29])<<8 | uint32(k[30])<<16 | uint32(k[31])<<24
+ x15 := uint32(c[12]) | uint32(c[13])<<8 | uint32(c[14])<<16 | uint32(c[15])<<24
+
+ for i := 0; i < 20; 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)
+ }
+ out[0] = byte(x0)
+ out[1] = byte(x0 >> 8)
+ out[2] = byte(x0 >> 16)
+ out[3] = byte(x0 >> 24)
+
+ out[4] = byte(x5)
+ out[5] = byte(x5 >> 8)
+ out[6] = byte(x5 >> 16)
+ out[7] = byte(x5 >> 24)
+
+ out[8] = byte(x10)
+ out[9] = byte(x10 >> 8)
+ out[10] = byte(x10 >> 16)
+ out[11] = byte(x10 >> 24)
+
+ out[12] = byte(x15)
+ out[13] = byte(x15 >> 8)
+ out[14] = byte(x15 >> 16)
+ out[15] = byte(x15 >> 24)
+
+ out[16] = byte(x6)
+ out[17] = byte(x6 >> 8)
+ out[18] = byte(x6 >> 16)
+ out[19] = byte(x6 >> 24)
+
+ out[20] = byte(x7)
+ out[21] = byte(x7 >> 8)
+ out[22] = byte(x7 >> 16)
+ out[23] = byte(x7 >> 24)
+
+ out[24] = byte(x8)
+ out[25] = byte(x8 >> 8)
+ out[26] = byte(x8 >> 16)
+ out[27] = byte(x8 >> 24)
+
+ out[28] = byte(x9)
+ out[29] = byte(x9 >> 8)
+ out[30] = byte(x9 >> 16)
+ out[31] = byte(x9 >> 24)
+}
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