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 | 112 |
1 files changed, 70 insertions, 42 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 523751f..6570847 100644 --- a/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go +++ b/vendor/golang.org/x/crypto/internal/chacha20/chacha_generic.go @@ -32,6 +32,30 @@ func New(key [8]uint32, nonce [3]uint32) *Cipher { return &Cipher{key: key, nonce: nonce} } +// ChaCha20 constants spelling "expand 32-byte k" +const ( + j0 uint32 = 0x61707865 + j1 uint32 = 0x3320646e + j2 uint32 = 0x79622d32 + j3 uint32 = 0x6b206574 +) + +func quarterRound(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 +} + // 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. // @@ -73,6 +97,9 @@ func (s *Cipher) XORKeyStream(dst, src []byte) { return } if haveAsm { + if uint64(len(src))+uint64(s.counter)*64 > (1<<38)-64 { + panic("chacha20: counter overflow") + } s.xorKeyStreamAsm(dst, src) return } @@ -85,59 +112,34 @@ func (s *Cipher) XORKeyStream(dst, src []byte) { 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]) + s1, s5, s9, s13 := quarterRound(j1, s.key[1], s.key[5], s.nonce[0]) + s2, s6, s10, s14 := quarterRound(j2, s.key[2], s.key[6], s.nonce[1]) + s3, s7, s11, s15 := quarterRound(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) + s0, s4, s8, s12 := quarterRound(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) + x0, x5, x10, x15 := quarterRound(s0, s5, s10, s15) + x1, x6, x11, x12 := quarterRound(s1, s6, s11, s12) + x2, x7, x8, x13 := quarterRound(s2, s7, s8, s13) + x3, x4, x9, x14 := quarterRound(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, x4, x8, x12 = quarterRound(x0, x4, x8, x12) + x1, x5, x9, x13 = quarterRound(x1, x5, x9, x13) + x2, x6, x10, x14 = quarterRound(x2, x6, x10, x14) + x3, x7, x11, x15 = quarterRound(x3, x7, x11, x15) + + x0, x5, x10, x15 = quarterRound(x0, x5, x10, x15) + x1, x6, x11, x12 = quarterRound(x1, x6, x11, x12) + x2, x7, x8, x13 = quarterRound(x2, x7, x8, x13) + x3, x4, x9, x14 = quarterRound(x3, x4, x9, x14) } x0 += j0 @@ -234,3 +236,29 @@ func XORKeyStream(out, in []byte, counter *[16]byte, key *[32]byte) { } s.XORKeyStream(out, in) } + +// HChaCha20 uses the ChaCha20 core to generate a derived key from a key and a +// nonce. It should only be used as part of the XChaCha20 construction. +func HChaCha20(key *[8]uint32, nonce *[4]uint32) [8]uint32 { + x0, x1, x2, x3 := j0, j1, j2, j3 + x4, x5, x6, x7 := key[0], key[1], key[2], key[3] + x8, x9, x10, x11 := key[4], key[5], key[6], key[7] + x12, x13, x14, x15 := nonce[0], nonce[1], nonce[2], nonce[3] + + for i := 0; i < 10; i++ { + x0, x4, x8, x12 = quarterRound(x0, x4, x8, x12) + x1, x5, x9, x13 = quarterRound(x1, x5, x9, x13) + x2, x6, x10, x14 = quarterRound(x2, x6, x10, x14) + x3, x7, x11, x15 = quarterRound(x3, x7, x11, x15) + + x0, x5, x10, x15 = quarterRound(x0, x5, x10, x15) + x1, x6, x11, x12 = quarterRound(x1, x6, x11, x12) + x2, x7, x8, x13 = quarterRound(x2, x7, x8, x13) + x3, x4, x9, x14 = quarterRound(x3, x4, x9, x14) + } + + var out [8]uint32 + out[0], out[1], out[2], out[3] = x0, x1, x2, x3 + out[4], out[5], out[6], out[7] = x12, x13, x14, x15 + return out +} |