diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go')
| -rw-r--r-- | vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go | 402 |
1 files changed, 220 insertions, 182 deletions
diff --git a/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go b/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go index 0f8efdb..523751f 100644 --- a/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go +++ b/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go @@ -2,197 +2,235 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. -// Package ChaCha20 implements the core ChaCha20 function as specified in https://tools.ietf.org/html/rfc7539#section-2.3. +// Package ChaCha20 implements the core ChaCha20 function as specified +// in https://tools.ietf.org/html/rfc7539#section-2.3. package chacha20 -import "encoding/binary" - -const rounds = 20 - -// core applies the ChaCha20 core function to 16-byte input in, 32-byte key k, -// and 16-byte constant c, and puts the result into 64-byte array out. -func core(out *[64]byte, in *[16]byte, k *[32]byte) { - j0 := uint32(0x61707865) - j1 := uint32(0x3320646e) - j2 := uint32(0x79622d32) - j3 := uint32(0x6b206574) - j4 := binary.LittleEndian.Uint32(k[0:4]) - j5 := binary.LittleEndian.Uint32(k[4:8]) - j6 := binary.LittleEndian.Uint32(k[8:12]) - j7 := binary.LittleEndian.Uint32(k[12:16]) - j8 := binary.LittleEndian.Uint32(k[16:20]) - j9 := binary.LittleEndian.Uint32(k[20:24]) - j10 := binary.LittleEndian.Uint32(k[24:28]) - j11 := binary.LittleEndian.Uint32(k[28:32]) - j12 := binary.LittleEndian.Uint32(in[0:4]) - j13 := binary.LittleEndian.Uint32(in[4:8]) - j14 := binary.LittleEndian.Uint32(in[8:12]) - j15 := binary.LittleEndian.Uint32(in[12:16]) - - x0, x1, x2, x3, x4, x5, x6, x7 := j0, j1, j2, j3, j4, j5, j6, j7 - x8, x9, x10, x11, x12, x13, x14, x15 := j8, j9, j10, j11, j12, j13, j14, j15 - - for i := 0; i < rounds; i += 2 { - x0 += x4 - x12 ^= x0 - x12 = (x12 << 16) | (x12 >> (16)) - x8 += x12 - x4 ^= x8 - x4 = (x4 << 12) | (x4 >> (20)) - x0 += x4 - x12 ^= x0 - x12 = (x12 << 8) | (x12 >> (24)) - x8 += x12 - x4 ^= x8 - x4 = (x4 << 7) | (x4 >> (25)) - x1 += x5 - x13 ^= x1 - x13 = (x13 << 16) | (x13 >> 16) - x9 += x13 - x5 ^= x9 - x5 = (x5 << 12) | (x5 >> 20) - x1 += x5 - x13 ^= x1 - x13 = (x13 << 8) | (x13 >> 24) - x9 += x13 - x5 ^= x9 - x5 = (x5 << 7) | (x5 >> 25) - x2 += x6 - x14 ^= x2 - x14 = (x14 << 16) | (x14 >> 16) - x10 += x14 - x6 ^= x10 - x6 = (x6 << 12) | (x6 >> 20) - x2 += x6 - x14 ^= x2 - x14 = (x14 << 8) | (x14 >> 24) - x10 += x14 - x6 ^= x10 - x6 = (x6 << 7) | (x6 >> 25) - x3 += x7 - x15 ^= x3 - x15 = (x15 << 16) | (x15 >> 16) - x11 += x15 - x7 ^= x11 - x7 = (x7 << 12) | (x7 >> 20) - x3 += x7 - x15 ^= x3 - x15 = (x15 << 8) | (x15 >> 24) - x11 += x15 - x7 ^= x11 - x7 = (x7 << 7) | (x7 >> 25) - x0 += x5 - x15 ^= x0 - x15 = (x15 << 16) | (x15 >> 16) - x10 += x15 - x5 ^= x10 - x5 = (x5 << 12) | (x5 >> 20) - x0 += x5 - x15 ^= x0 - x15 = (x15 << 8) | (x15 >> 24) - x10 += x15 - x5 ^= x10 - x5 = (x5 << 7) | (x5 >> 25) - x1 += x6 - x12 ^= x1 - x12 = (x12 << 16) | (x12 >> 16) - x11 += x12 - x6 ^= x11 - x6 = (x6 << 12) | (x6 >> 20) - x1 += x6 - x12 ^= x1 - x12 = (x12 << 8) | (x12 >> 24) - x11 += x12 - x6 ^= x11 - x6 = (x6 << 7) | (x6 >> 25) - x2 += x7 - x13 ^= x2 - x13 = (x13 << 16) | (x13 >> 16) - x8 += x13 - x7 ^= x8 - x7 = (x7 << 12) | (x7 >> 20) - x2 += x7 - x13 ^= x2 - x13 = (x13 << 8) | (x13 >> 24) - x8 += x13 - x7 ^= x8 - x7 = (x7 << 7) | (x7 >> 25) - x3 += x4 - x14 ^= x3 - x14 = (x14 << 16) | (x14 >> 16) - x9 += x14 - x4 ^= x9 - x4 = (x4 << 12) | (x4 >> 20) - x3 += x4 - x14 ^= x3 - x14 = (x14 << 8) | (x14 >> 24) - x9 += x14 - x4 ^= x9 - x4 = (x4 << 7) | (x4 >> 25) - } +import ( + "crypto/cipher" + "encoding/binary" + + "golang.org/x/crypto/internal/subtle" +) + +// assert that *Cipher implements cipher.Stream +var _ cipher.Stream = (*Cipher)(nil) - x0 += j0 - x1 += j1 - x2 += j2 - x3 += j3 - x4 += j4 - x5 += j5 - x6 += j6 - x7 += j7 - x8 += j8 - x9 += j9 - x10 += j10 - x11 += j11 - x12 += j12 - x13 += j13 - x14 += j14 - x15 += j15 - - binary.LittleEndian.PutUint32(out[0:4], x0) - binary.LittleEndian.PutUint32(out[4:8], x1) - binary.LittleEndian.PutUint32(out[8:12], x2) - binary.LittleEndian.PutUint32(out[12:16], x3) - binary.LittleEndian.PutUint32(out[16:20], x4) - binary.LittleEndian.PutUint32(out[20:24], x5) - binary.LittleEndian.PutUint32(out[24:28], x6) - binary.LittleEndian.PutUint32(out[28:32], x7) - binary.LittleEndian.PutUint32(out[32:36], x8) - binary.LittleEndian.PutUint32(out[36:40], x9) - binary.LittleEndian.PutUint32(out[40:44], x10) - binary.LittleEndian.PutUint32(out[44:48], x11) - binary.LittleEndian.PutUint32(out[48:52], x12) - binary.LittleEndian.PutUint32(out[52:56], x13) - binary.LittleEndian.PutUint32(out[56:60], x14) - binary.LittleEndian.PutUint32(out[60:64], x15) +// Cipher is a stateful instance of ChaCha20 using a particular key +// and nonce. A *Cipher implements the cipher.Stream interface. +type Cipher struct { + key [8]uint32 + counter uint32 // incremented after each block + nonce [3]uint32 + buf [bufSize]byte // buffer for unused keystream bytes + len int // number of unused keystream bytes at end of buf } -// XORKeyStream crypts bytes from in to out using the given key and counters. -// In and out must overlap entirely or not at all. Counter contains the raw -// ChaCha20 counter bytes (i.e. block counter followed by nonce). -func XORKeyStream(out, in []byte, counter *[16]byte, key *[32]byte) { - var block [64]byte - var counterCopy [16]byte - copy(counterCopy[:], counter[:]) - - for len(in) >= 64 { - core(&block, &counterCopy, key) - for i, x := range block { - out[i] = in[i] ^ x +// New creates a new ChaCha20 stream cipher with the given key and nonce. +// The initial counter value is set to 0. +func New(key [8]uint32, nonce [3]uint32) *Cipher { + return &Cipher{key: key, nonce: nonce} +} + +// XORKeyStream XORs each byte in the given slice with a byte from the +// cipher's key stream. Dst and src must overlap entirely or not at all. +// +// If len(dst) < len(src), XORKeyStream will panic. It is acceptable +// to pass a dst bigger than src, and in that case, XORKeyStream will +// only update dst[:len(src)] and will not touch the rest of dst. +// +// Multiple calls to XORKeyStream behave as if the concatenation of +// the src buffers was passed in a single run. That is, Cipher +// maintains state and does not reset at each XORKeyStream call. +func (s *Cipher) XORKeyStream(dst, src []byte) { + if len(dst) < len(src) { + panic("chacha20: output smaller than input") + } + if subtle.InexactOverlap(dst[:len(src)], src) { + panic("chacha20: invalid buffer overlap") + } + + // xor src with buffered keystream first + if s.len != 0 { + buf := s.buf[len(s.buf)-s.len:] + if len(src) < len(buf) { + buf = buf[:len(src)] + } + td, ts := dst[:len(buf)], src[:len(buf)] // BCE hint + for i, b := range buf { + td[i] = ts[i] ^ b } - u := uint32(1) - for i := 0; i < 4; i++ { - u += uint32(counterCopy[i]) - counterCopy[i] = byte(u) - u >>= 8 + s.len -= len(buf) + if s.len != 0 { + return } - in = in[64:] - out = out[64:] + s.buf = [len(s.buf)]byte{} // zero the empty buffer + src = src[len(buf):] + dst = dst[len(buf):] + } + + if len(src) == 0 { + return + } + if haveAsm { + s.xorKeyStreamAsm(dst, src) + return } - if len(in) > 0 { - core(&block, &counterCopy, key) - for i, v := range in { - out[i] = v ^ block[i] + // set up a 64-byte buffer to pad out the final block if needed + // (hoisted out of the main loop to avoid spills) + rem := len(src) % 64 // length of final block + fin := len(src) - rem // index of final block + if rem > 0 { + copy(s.buf[len(s.buf)-64:], src[fin:]) + } + + // qr calculates a quarter round + qr := func(a, b, c, d uint32) (uint32, uint32, uint32, uint32) { + a += b + d ^= a + d = (d << 16) | (d >> 16) + c += d + b ^= c + b = (b << 12) | (b >> 20) + a += b + d ^= a + d = (d << 8) | (d >> 24) + c += d + b ^= c + b = (b << 7) | (b >> 25) + return a, b, c, d + } + + // ChaCha20 constants + const ( + j0 = 0x61707865 + j1 = 0x3320646e + j2 = 0x79622d32 + j3 = 0x6b206574 + ) + + // pre-calculate most of the first round + s1, s5, s9, s13 := qr(j1, s.key[1], s.key[5], s.nonce[0]) + s2, s6, s10, s14 := qr(j2, s.key[2], s.key[6], s.nonce[1]) + s3, s7, s11, s15 := qr(j3, s.key[3], s.key[7], s.nonce[2]) + + n := len(src) + src, dst = src[:n:n], dst[:n:n] // BCE hint + for i := 0; i < n; i += 64 { + // calculate the remainder of the first round + s0, s4, s8, s12 := qr(j0, s.key[0], s.key[4], s.counter) + + // execute the second round + x0, x5, x10, x15 := qr(s0, s5, s10, s15) + x1, x6, x11, x12 := qr(s1, s6, s11, s12) + x2, x7, x8, x13 := qr(s2, s7, s8, s13) + x3, x4, x9, x14 := qr(s3, s4, s9, s14) + + // execute the remaining 18 rounds + for i := 0; i < 9; i++ { + x0, x4, x8, x12 = qr(x0, x4, x8, x12) + x1, x5, x9, x13 = qr(x1, x5, x9, x13) + x2, x6, x10, x14 = qr(x2, x6, x10, x14) + x3, x7, x11, x15 = qr(x3, x7, x11, x15) + + x0, x5, x10, x15 = qr(x0, x5, x10, x15) + x1, x6, x11, x12 = qr(x1, x6, x11, x12) + x2, x7, x8, x13 = qr(x2, x7, x8, x13) + x3, x4, x9, x14 = qr(x3, x4, x9, x14) } + + x0 += j0 + x1 += j1 + x2 += j2 + x3 += j3 + + x4 += s.key[0] + x5 += s.key[1] + x6 += s.key[2] + x7 += s.key[3] + x8 += s.key[4] + x9 += s.key[5] + x10 += s.key[6] + x11 += s.key[7] + + x12 += s.counter + x13 += s.nonce[0] + x14 += s.nonce[1] + x15 += s.nonce[2] + + // increment the counter + s.counter += 1 + if s.counter == 0 { + panic("chacha20: counter overflow") + } + + // pad to 64 bytes if needed + in, out := src[i:], dst[i:] + if i == fin { + // src[fin:] has already been copied into s.buf before + // the main loop + in, out = s.buf[len(s.buf)-64:], s.buf[len(s.buf)-64:] + } + in, out = in[:64], out[:64] // BCE hint + + // XOR the key stream with the source and write out the result + xor(out[0:], in[0:], x0) + xor(out[4:], in[4:], x1) + xor(out[8:], in[8:], x2) + xor(out[12:], in[12:], x3) + xor(out[16:], in[16:], x4) + xor(out[20:], in[20:], x5) + xor(out[24:], in[24:], x6) + xor(out[28:], in[28:], x7) + xor(out[32:], in[32:], x8) + xor(out[36:], in[36:], x9) + xor(out[40:], in[40:], x10) + xor(out[44:], in[44:], x11) + xor(out[48:], in[48:], x12) + xor(out[52:], in[52:], x13) + xor(out[56:], in[56:], x14) + xor(out[60:], in[60:], x15) + } + // copy any trailing bytes out of the buffer and into dst + if rem != 0 { + s.len = 64 - rem + copy(dst[fin:], s.buf[len(s.buf)-64:]) + } +} + +// Advance discards bytes in the key stream until the next 64 byte block +// boundary is reached and updates the counter accordingly. If the key +// stream is already at a block boundary no bytes will be discarded and +// the counter will be unchanged. +func (s *Cipher) Advance() { + s.len -= s.len % 64 + if s.len == 0 { + s.buf = [len(s.buf)]byte{} + } +} + +// XORKeyStream crypts bytes from in to out using the given key and counters. +// In and out must overlap entirely or not at all. Counter contains the raw +// ChaCha20 counter bytes (i.e. block counter followed by nonce). +func XORKeyStream(out, in []byte, counter *[16]byte, key *[32]byte) { + s := Cipher{ + key: [8]uint32{ + binary.LittleEndian.Uint32(key[0:4]), + binary.LittleEndian.Uint32(key[4:8]), + binary.LittleEndian.Uint32(key[8:12]), + binary.LittleEndian.Uint32(key[12:16]), + binary.LittleEndian.Uint32(key[16:20]), + binary.LittleEndian.Uint32(key[20:24]), + binary.LittleEndian.Uint32(key[24:28]), + binary.LittleEndian.Uint32(key[28:32]), + }, + nonce: [3]uint32{ + binary.LittleEndian.Uint32(counter[4:8]), + binary.LittleEndian.Uint32(counter[8:12]), + binary.LittleEndian.Uint32(counter[12:16]), + }, + counter: binary.LittleEndian.Uint32(counter[0:4]), } + s.XORKeyStream(out, in) } |