diff options
Diffstat (limited to 'xchacha20.go')
| -rw-r--r-- | xchacha20.go | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/xchacha20.go b/xchacha20.go new file mode 100644 index 0000000..5d963e0 --- /dev/null +++ b/xchacha20.go @@ -0,0 +1,169 @@ +// Copyright (c) 2016 Andreas Auernhammer. All rights reserved. +// Use of this source code is governed by a license that can be +// found in the LICENSE file. + +package main + +import ( + "encoding/binary" + "golang.org/x/crypto/chacha20poly1305" +) + +func HChaCha20(out *[32]byte, nonce []byte, key *[32]byte) { + + v00 := uint32(0x61707865) + v01 := uint32(0x3320646e) + v02 := uint32(0x79622d32) + v03 := uint32(0x6b206574) + + v04 := binary.LittleEndian.Uint32(key[0:]) + v05 := binary.LittleEndian.Uint32(key[4:]) + v06 := binary.LittleEndian.Uint32(key[8:]) + v07 := binary.LittleEndian.Uint32(key[12:]) + v08 := binary.LittleEndian.Uint32(key[16:]) + v09 := binary.LittleEndian.Uint32(key[20:]) + v10 := binary.LittleEndian.Uint32(key[24:]) + v11 := binary.LittleEndian.Uint32(key[28:]) + v12 := binary.LittleEndian.Uint32(nonce[0:]) + v13 := binary.LittleEndian.Uint32(nonce[4:]) + v14 := binary.LittleEndian.Uint32(nonce[8:]) + v15 := binary.LittleEndian.Uint32(nonce[12:]) + + for i := 0; i < 20; i += 2 { + v00 += v04 + v12 ^= v00 + v12 = (v12 << 16) | (v12 >> 16) + v08 += v12 + v04 ^= v08 + v04 = (v04 << 12) | (v04 >> 20) + v00 += v04 + v12 ^= v00 + v12 = (v12 << 8) | (v12 >> 24) + v08 += v12 + v04 ^= v08 + v04 = (v04 << 7) | (v04 >> 25) + v01 += v05 + v13 ^= v01 + v13 = (v13 << 16) | (v13 >> 16) + v09 += v13 + v05 ^= v09 + v05 = (v05 << 12) | (v05 >> 20) + v01 += v05 + v13 ^= v01 + v13 = (v13 << 8) | (v13 >> 24) + v09 += v13 + v05 ^= v09 + v05 = (v05 << 7) | (v05 >> 25) + v02 += v06 + v14 ^= v02 + v14 = (v14 << 16) | (v14 >> 16) + v10 += v14 + v06 ^= v10 + v06 = (v06 << 12) | (v06 >> 20) + v02 += v06 + v14 ^= v02 + v14 = (v14 << 8) | (v14 >> 24) + v10 += v14 + v06 ^= v10 + v06 = (v06 << 7) | (v06 >> 25) + v03 += v07 + v15 ^= v03 + v15 = (v15 << 16) | (v15 >> 16) + v11 += v15 + v07 ^= v11 + v07 = (v07 << 12) | (v07 >> 20) + v03 += v07 + v15 ^= v03 + v15 = (v15 << 8) | (v15 >> 24) + v11 += v15 + v07 ^= v11 + v07 = (v07 << 7) | (v07 >> 25) + v00 += v05 + v15 ^= v00 + v15 = (v15 << 16) | (v15 >> 16) + v10 += v15 + v05 ^= v10 + v05 = (v05 << 12) | (v05 >> 20) + v00 += v05 + v15 ^= v00 + v15 = (v15 << 8) | (v15 >> 24) + v10 += v15 + v05 ^= v10 + v05 = (v05 << 7) | (v05 >> 25) + v01 += v06 + v12 ^= v01 + v12 = (v12 << 16) | (v12 >> 16) + v11 += v12 + v06 ^= v11 + v06 = (v06 << 12) | (v06 >> 20) + v01 += v06 + v12 ^= v01 + v12 = (v12 << 8) | (v12 >> 24) + v11 += v12 + v06 ^= v11 + v06 = (v06 << 7) | (v06 >> 25) + v02 += v07 + v13 ^= v02 + v13 = (v13 << 16) | (v13 >> 16) + v08 += v13 + v07 ^= v08 + v07 = (v07 << 12) | (v07 >> 20) + v02 += v07 + v13 ^= v02 + v13 = (v13 << 8) | (v13 >> 24) + v08 += v13 + v07 ^= v08 + v07 = (v07 << 7) | (v07 >> 25) + v03 += v04 + v14 ^= v03 + v14 = (v14 << 16) | (v14 >> 16) + v09 += v14 + v04 ^= v09 + v04 = (v04 << 12) | (v04 >> 20) + v03 += v04 + v14 ^= v03 + v14 = (v14 << 8) | (v14 >> 24) + v09 += v14 + v04 ^= v09 + v04 = (v04 << 7) | (v04 >> 25) + } + + binary.LittleEndian.PutUint32(out[0:], v00) + binary.LittleEndian.PutUint32(out[4:], v01) + binary.LittleEndian.PutUint32(out[8:], v02) + binary.LittleEndian.PutUint32(out[12:], v03) + binary.LittleEndian.PutUint32(out[16:], v12) + binary.LittleEndian.PutUint32(out[20:], v13) + binary.LittleEndian.PutUint32(out[24:], v14) + binary.LittleEndian.PutUint32(out[28:], v15) +} + +func XChaCha20Poly1305Encrypt( + dst []byte, + nonceFull *[24]byte, + plaintext []byte, + additionalData []byte, + key *[chacha20poly1305.KeySize]byte, +) []byte { + var nonce [chacha20poly1305.NonceSize]byte + var derivedKey [chacha20poly1305.KeySize]byte + HChaCha20(&derivedKey, nonceFull[:16], key) + aead, _ := chacha20poly1305.New(derivedKey[:]) + copy(nonce[4:], nonceFull[16:]) + return aead.Seal(dst, nonce[:], plaintext, additionalData) +} + +func XChaCha20Poly1305Decrypt( + dst []byte, + nonceFull *[24]byte, + plaintext []byte, + additionalData []byte, + key *[chacha20poly1305.KeySize]byte, +) ([]byte, error) { + var nonce [chacha20poly1305.NonceSize]byte + var derivedKey [chacha20poly1305.KeySize]byte + HChaCha20(&derivedKey, nonceFull[:16], key) + aead, _ := chacha20poly1305.New(derivedKey[:]) + copy(nonce[4:], nonceFull[16:]) + return aead.Open(dst, nonce[:], plaintext, additionalData) +} |