170 lines
4.0 KiB
Go
170 lines
4.0 KiB
Go
// Copyright (c) 2016 Andreas Auernhammer. All rights reserved.
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// Use of this source code is governed by a license that can be
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// found in the LICENSE file.
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package xchacha20poly1305
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import (
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"encoding/binary"
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"golang.org/x/crypto/chacha20poly1305"
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)
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func hChaCha20(out *[32]byte, nonce []byte, key *[32]byte) {
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v00 := uint32(0x61707865)
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v01 := uint32(0x3320646e)
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v02 := uint32(0x79622d32)
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v03 := uint32(0x6b206574)
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v04 := binary.LittleEndian.Uint32(key[0:])
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v05 := binary.LittleEndian.Uint32(key[4:])
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v06 := binary.LittleEndian.Uint32(key[8:])
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v07 := binary.LittleEndian.Uint32(key[12:])
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v08 := binary.LittleEndian.Uint32(key[16:])
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v09 := binary.LittleEndian.Uint32(key[20:])
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v10 := binary.LittleEndian.Uint32(key[24:])
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v11 := binary.LittleEndian.Uint32(key[28:])
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v12 := binary.LittleEndian.Uint32(nonce[0:])
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v13 := binary.LittleEndian.Uint32(nonce[4:])
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v14 := binary.LittleEndian.Uint32(nonce[8:])
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v15 := binary.LittleEndian.Uint32(nonce[12:])
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for i := 0; i < 20; i += 2 {
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v00 += v04
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v12 ^= v00
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v12 = (v12 << 16) | (v12 >> 16)
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v08 += v12
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v04 ^= v08
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v04 = (v04 << 12) | (v04 >> 20)
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v00 += v04
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v12 ^= v00
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v12 = (v12 << 8) | (v12 >> 24)
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v08 += v12
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v04 ^= v08
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v04 = (v04 << 7) | (v04 >> 25)
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v01 += v05
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v13 ^= v01
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v13 = (v13 << 16) | (v13 >> 16)
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v09 += v13
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v05 ^= v09
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v05 = (v05 << 12) | (v05 >> 20)
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v01 += v05
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v13 ^= v01
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v13 = (v13 << 8) | (v13 >> 24)
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v09 += v13
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v05 ^= v09
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v05 = (v05 << 7) | (v05 >> 25)
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v02 += v06
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v14 ^= v02
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v14 = (v14 << 16) | (v14 >> 16)
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v10 += v14
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v06 ^= v10
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v06 = (v06 << 12) | (v06 >> 20)
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v02 += v06
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v14 ^= v02
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v14 = (v14 << 8) | (v14 >> 24)
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v10 += v14
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v06 ^= v10
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v06 = (v06 << 7) | (v06 >> 25)
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v03 += v07
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v15 ^= v03
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v15 = (v15 << 16) | (v15 >> 16)
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v11 += v15
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v07 ^= v11
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v07 = (v07 << 12) | (v07 >> 20)
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v03 += v07
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v15 ^= v03
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v15 = (v15 << 8) | (v15 >> 24)
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v11 += v15
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v07 ^= v11
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v07 = (v07 << 7) | (v07 >> 25)
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v00 += v05
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v15 ^= v00
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v15 = (v15 << 16) | (v15 >> 16)
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v10 += v15
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v05 ^= v10
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v05 = (v05 << 12) | (v05 >> 20)
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v00 += v05
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v15 ^= v00
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v15 = (v15 << 8) | (v15 >> 24)
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v10 += v15
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v05 ^= v10
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v05 = (v05 << 7) | (v05 >> 25)
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v01 += v06
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v12 ^= v01
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v12 = (v12 << 16) | (v12 >> 16)
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v11 += v12
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v06 ^= v11
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v06 = (v06 << 12) | (v06 >> 20)
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v01 += v06
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v12 ^= v01
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v12 = (v12 << 8) | (v12 >> 24)
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v11 += v12
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v06 ^= v11
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v06 = (v06 << 7) | (v06 >> 25)
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v02 += v07
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v13 ^= v02
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v13 = (v13 << 16) | (v13 >> 16)
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v08 += v13
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v07 ^= v08
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v07 = (v07 << 12) | (v07 >> 20)
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v02 += v07
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v13 ^= v02
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v13 = (v13 << 8) | (v13 >> 24)
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v08 += v13
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v07 ^= v08
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v07 = (v07 << 7) | (v07 >> 25)
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v03 += v04
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v14 ^= v03
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v14 = (v14 << 16) | (v14 >> 16)
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v09 += v14
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v04 ^= v09
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v04 = (v04 << 12) | (v04 >> 20)
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v03 += v04
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v14 ^= v03
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v14 = (v14 << 8) | (v14 >> 24)
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v09 += v14
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v04 ^= v09
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v04 = (v04 << 7) | (v04 >> 25)
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}
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binary.LittleEndian.PutUint32(out[0:], v00)
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binary.LittleEndian.PutUint32(out[4:], v01)
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binary.LittleEndian.PutUint32(out[8:], v02)
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binary.LittleEndian.PutUint32(out[12:], v03)
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binary.LittleEndian.PutUint32(out[16:], v12)
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binary.LittleEndian.PutUint32(out[20:], v13)
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binary.LittleEndian.PutUint32(out[24:], v14)
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binary.LittleEndian.PutUint32(out[28:], v15)
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}
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func Encrypt(
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dst []byte,
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nonceFull *[24]byte,
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plaintext []byte,
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additionalData []byte,
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key *[chacha20poly1305.KeySize]byte,
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) []byte {
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var nonce [chacha20poly1305.NonceSize]byte
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var derivedKey [chacha20poly1305.KeySize]byte
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hChaCha20(&derivedKey, nonceFull[:16], key)
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aead, _ := chacha20poly1305.New(derivedKey[:])
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copy(nonce[4:], nonceFull[16:])
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return aead.Seal(dst, nonce[:], plaintext, additionalData)
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}
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func Decrypt(
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dst []byte,
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nonceFull *[24]byte,
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plaintext []byte,
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additionalData []byte,
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key *[chacha20poly1305.KeySize]byte,
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) ([]byte, error) {
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var nonce [chacha20poly1305.NonceSize]byte
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var derivedKey [chacha20poly1305.KeySize]byte
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hChaCha20(&derivedKey, nonceFull[:16], key)
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aead, _ := chacha20poly1305.New(derivedKey[:])
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copy(nonce[4:], nonceFull[16:])
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return aead.Open(dst, nonce[:], plaintext, additionalData)
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}
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