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// Copyright 2016 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 go1.7,amd64,!gccgo,!appengine
package chacha20poly1305
import "encoding/binary"
//go:noescape
func chacha20Poly1305Open(dst []byte, key []uint32, src, ad []byte) bool
//go:noescape
func chacha20Poly1305Seal(dst []byte, key []uint32, src, ad []byte)
//go:noescape
func haveSSSE3() bool
var canUseASM bool
func init() {
canUseASM = haveSSSE3()
}
// setupState writes a ChaCha20 input matrix to state. See
// https://tools.ietf.org/html/rfc7539#section-2.3.
func setupState(state *[16]uint32, key *[32]byte, nonce []byte) {
state[0] = 0x61707865
state[1] = 0x3320646e
state[2] = 0x79622d32
state[3] = 0x6b206574
state[4] = binary.LittleEndian.Uint32(key[:4])
state[5] = binary.LittleEndian.Uint32(key[4:8])
state[6] = binary.LittleEndian.Uint32(key[8:12])
state[7] = binary.LittleEndian.Uint32(key[12:16])
state[8] = binary.LittleEndian.Uint32(key[16:20])
state[9] = binary.LittleEndian.Uint32(key[20:24])
state[10] = binary.LittleEndian.Uint32(key[24:28])
state[11] = binary.LittleEndian.Uint32(key[28:32])
state[12] = 0
state[13] = binary.LittleEndian.Uint32(nonce[:4])
state[14] = binary.LittleEndian.Uint32(nonce[4:8])
state[15] = binary.LittleEndian.Uint32(nonce[8:12])
}
func (c *chacha20poly1305) seal(dst, nonce, plaintext, additionalData []byte) []byte {
if !canUseASM {
return c.sealGeneric(dst, nonce, plaintext, additionalData)
}
var state [16]uint32
setupState(&state, &c.key, nonce)
ret, out := sliceForAppend(dst, len(plaintext)+16)
chacha20Poly1305Seal(out[:], state[:], plaintext, additionalData)
return ret
}
func (c *chacha20poly1305) open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
if !canUseASM {
return c.openGeneric(dst, nonce, ciphertext, additionalData)
}
var state [16]uint32
setupState(&state, &c.key, nonce)
ciphertext = ciphertext[:len(ciphertext)-16]
ret, out := sliceForAppend(dst, len(ciphertext))
if !chacha20Poly1305Open(out, state[:], ciphertext, additionalData) {
for i := range out {
out[i] = 0
}
return nil, errOpen
}
return ret, nil
}
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