Zaki Manian
7 years ago
1 changed files with 237 additions and 0 deletions
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+237 -0xchacha20poly1035/xchachapoly.go
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xchacha20poly1035/xchachapoly.go
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| @ -0,0 +1,237 @@ | |||
| package xchacha20poly1305 | |||
| import ( | |||
| "crypto/cipher" | |||
| "encoding/binary" | |||
| "errors" | |||
| "golang.org/x/crypto/chacha20poly1305" | |||
| ) | |||
| var sigma = [4]uint32{0x61707865, 0x3320646e, 0x79622d32, 0x6b206574} | |||
| type xchacha20poly1305 struct { | |||
| key [KeySize]byte | |||
| } | |||
| const ( | |||
| // KeySize is the size of the key used by this AEAD, in bytes. | |||
| KeySize = 32 | |||
| // NonceSize is the size of the nonce used with this AEAD, in bytes. | |||
| NonceSize = 24 | |||
| ) | |||
| //New xChaChapoly1305 AEAD with 24 byte nonces | |||
| func New(key []byte) (cipher.AEAD, error) { | |||
| if len(key) != KeySize { | |||
| return nil, errors.New("chacha20poly1305: bad key length") | |||
| } | |||
| ret := new(xchacha20poly1305) | |||
| copy(ret.key[:], key) | |||
| return ret, nil | |||
| } | |||
| func (c *xchacha20poly1305) NonceSize() int { | |||
| return NonceSize | |||
| } | |||
| func (c *xchacha20poly1305) Overhead() int { | |||
| return 16 | |||
| } | |||
| func (c *xchacha20poly1305) Seal(dst, nonce, plaintext, additionalData []byte) []byte { | |||
| if len(nonce) != NonceSize { | |||
| panic("chacha20poly1305: bad nonce length passed to Seal") | |||
| } | |||
| if uint64(len(plaintext)) > (1<<38)-64 { | |||
| panic("chacha20poly1305: plaintext too large") | |||
| } | |||
| var subKey [KeySize]byte | |||
| var hNonce [16]byte | |||
| var subNonce [chacha20poly1305.NonceSize]byte | |||
| copy(hNonce[:], nonce[:16]) | |||
| HChaCha20(&subKey, &hNonce, &c.key) | |||
| chacha20poly1305, _ := chacha20poly1305.New(subKey[:]) | |||
| copy(subNonce[4:], nonce[16:]) | |||
| return chacha20poly1305.Seal(dst, subNonce[:], plaintext, additionalData) | |||
| } | |||
| func (c *xchacha20poly1305) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) { | |||
| if len(nonce) != NonceSize { | |||
| panic("chacha20poly1305: bad nonce length passed to Open") | |||
| } | |||
| if uint64(len(ciphertext)) > (1<<38)-48 { | |||
| panic("chacha20poly1305: ciphertext too large") | |||
| } | |||
| var subKey [KeySize]byte | |||
| var hNonce [16]byte | |||
| var subNonce [chacha20poly1305.NonceSize]byte | |||
| copy(hNonce[:], nonce[:16]) | |||
| HChaCha20(&subKey, &hNonce, &c.key) | |||
| chacha20poly1305, _ := chacha20poly1305.New(subKey[:]) | |||
| copy(subNonce[4:], nonce[16:]) | |||
| return chacha20poly1305.Open(dst, subNonce[:], ciphertext, additionalData) | |||
| } | |||
| // The MIT License (MIT) | |||
| // Copyright (c) 2016 Andreas Auernhammer | |||
| // Permission is hereby granted, free of charge, to any person obtaining a copy | |||
| // of this software and associated documentation files (the "Software"), to deal | |||
| // in the Software without restriction, including without limitation the rights | |||
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |||
| // copies of the Software, and to permit persons to whom the Software is | |||
| // furnished to do so, subject to the following conditions: | |||
| // The above copyright notice and this permission notice shall be included in all | |||
| // copies or substantial portions of the Software. | |||
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |||
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |||
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |||
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |||
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |||
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |||
| // SOFTWARE. | |||
| // HChaCha20 generates 32 pseudo-random bytes from a 128 bit nonce and a 256 bit secret key. | |||
| // It can be used as a key-derivation-function (KDF). | |||
| func HChaCha20(out *[32]byte, nonce *[16]byte, key *[32]byte) { hChaCha20Generic(out, nonce, key) } | |||
| func hChaCha20Generic(out *[32]byte, nonce *[16]byte, key *[32]byte) { | |||
| v00 := sigma[0] | |||
| v01 := sigma[1] | |||
| v02 := sigma[2] | |||
| v03 := sigma[3] | |||
| 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) | |||
| } | |||