From 1c8dffaa282ba9ebfe597e38f9849bc70f40efe5 Mon Sep 17 00:00:00 2001 From: Zaki Manian Date: Sun, 13 May 2018 11:06:20 -0400 Subject: [PATCH] Initial implementation of xchacha20poly1035 aead --- xchacha20poly1035/xchachapoly.go | 237 +++++++++++++++++++++++++++++++ 1 file changed, 237 insertions(+) create mode 100644 xchacha20poly1035/xchachapoly.go diff --git a/xchacha20poly1035/xchachapoly.go b/xchacha20poly1035/xchachapoly.go new file mode 100644 index 000000000..b9d823414 --- /dev/null +++ b/xchacha20poly1035/xchachapoly.go @@ -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) +}