80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build go1.7,amd64,!gccgo,!appengine
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package chacha20poly1305
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import (
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"encoding/binary"
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"golang.org/x/sys/cpu"
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)
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//go:noescape
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func chacha20Poly1305Open(dst []byte, key []uint32, src, ad []byte) bool
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//go:noescape
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func chacha20Poly1305Seal(dst []byte, key []uint32, src, ad []byte)
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var (
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useASM = cpu.X86.HasSSSE3
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useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI2
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)
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// setupState writes a ChaCha20 input matrix to state. See
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// https://tools.ietf.org/html/rfc7539#section-2.3.
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func setupState(state *[16]uint32, key *[8]uint32, nonce []byte) {
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state[0] = 0x61707865
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state[1] = 0x3320646e
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state[2] = 0x79622d32
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state[3] = 0x6b206574
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state[4] = key[0]
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state[5] = key[1]
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state[6] = key[2]
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state[7] = key[3]
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state[8] = key[4]
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state[9] = key[5]
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state[10] = key[6]
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state[11] = key[7]
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state[12] = 0
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state[13] = binary.LittleEndian.Uint32(nonce[:4])
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state[14] = binary.LittleEndian.Uint32(nonce[4:8])
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state[15] = binary.LittleEndian.Uint32(nonce[8:12])
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}
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func (c *chacha20poly1305) seal(dst, nonce, plaintext, additionalData []byte) []byte {
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if !useASM {
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return c.sealGeneric(dst, nonce, plaintext, additionalData)
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}
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var state [16]uint32
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setupState(&state, &c.key, nonce)
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ret, out := sliceForAppend(dst, len(plaintext)+16)
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chacha20Poly1305Seal(out[:], state[:], plaintext, additionalData)
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return ret
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}
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func (c *chacha20poly1305) open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
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if !useASM {
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return c.openGeneric(dst, nonce, ciphertext, additionalData)
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}
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var state [16]uint32
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setupState(&state, &c.key, nonce)
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ciphertext = ciphertext[:len(ciphertext)-16]
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ret, out := sliceForAppend(dst, len(ciphertext))
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if !chacha20Poly1305Open(out, state[:], ciphertext, additionalData) {
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for i := range out {
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out[i] = 0
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}
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return nil, errOpen
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}
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return ret, nil
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}
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