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-rw-r--r--vendor/golang.org/x/crypto/chacha20/chacha_generic.go119
-rw-r--r--vendor/golang.org/x/crypto/chacha20/xor.go17
2 files changed, 72 insertions, 64 deletions
diff --git a/vendor/golang.org/x/crypto/chacha20/chacha_generic.go b/vendor/golang.org/x/crypto/chacha20/chacha_generic.go
index 7c498e90..a2ecf5c3 100644
--- a/vendor/golang.org/x/crypto/chacha20/chacha_generic.go
+++ b/vendor/golang.org/x/crypto/chacha20/chacha_generic.go
@@ -42,10 +42,14 @@ type Cipher struct {
// The last len bytes of buf are leftover key stream bytes from the previous
// XORKeyStream invocation. The size of buf depends on how many blocks are
- // computed at a time.
+ // computed at a time by xorKeyStreamBlocks.
buf [bufSize]byte
len int
+ // overflow is set when the counter overflowed, no more blocks can be
+ // generated, and the next XORKeyStream call should panic.
+ overflow bool
+
// The counter-independent results of the first round are cached after they
// are computed the first time.
precompDone bool
@@ -89,6 +93,7 @@ func newUnauthenticatedCipher(c *Cipher, key, nonce []byte) (*Cipher, error) {
return nil, errors.New("chacha20: wrong nonce size")
}
+ key, nonce = key[:KeySize], nonce[:NonceSize] // bounds check elimination hint
c.key = [8]uint32{
binary.LittleEndian.Uint32(key[0:4]),
binary.LittleEndian.Uint32(key[4:8]),
@@ -139,15 +144,18 @@ func quarterRound(a, b, c, d uint32) (uint32, uint32, uint32, uint32) {
// SetCounter sets the Cipher counter. The next invocation of XORKeyStream will
// behave as if (64 * counter) bytes had been encrypted so far.
//
-// To prevent accidental counter reuse, SetCounter panics if counter is
-// less than the current value.
+// To prevent accidental counter reuse, SetCounter panics if counter is less
+// than the current value.
+//
+// Note that the execution time of XORKeyStream is not independent of the
+// counter value.
func (s *Cipher) SetCounter(counter uint32) {
// Internally, s may buffer multiple blocks, which complicates this
// implementation slightly. When checking whether the counter has rolled
// back, we must use both s.counter and s.len to determine how many blocks
// we have already output.
outputCounter := s.counter - uint32(s.len)/blockSize
- if counter < outputCounter {
+ if s.overflow || counter < outputCounter {
panic("chacha20: SetCounter attempted to rollback counter")
}
@@ -196,34 +204,52 @@ func (s *Cipher) XORKeyStream(dst, src []byte) {
dst[i] = src[i] ^ b
}
s.len -= len(keyStream)
- src = src[len(keyStream):]
- dst = dst[len(keyStream):]
+ dst, src = dst[len(keyStream):], src[len(keyStream):]
+ }
+ if len(src) == 0 {
+ return
}
- const blocksPerBuf = bufSize / blockSize
- numBufs := (uint64(len(src)) + bufSize - 1) / bufSize
- if uint64(s.counter)+numBufs*blocksPerBuf >= 1<<32 {
+ // If we'd need to let the counter overflow and keep generating output,
+ // panic immediately. If instead we'd only reach the last block, remember
+ // not to generate any more output after the buffer is drained.
+ numBlocks := (uint64(len(src)) + blockSize - 1) / blockSize
+ if s.overflow || uint64(s.counter)+numBlocks > 1<<32 {
panic("chacha20: counter overflow")
+ } else if uint64(s.counter)+numBlocks == 1<<32 {
+ s.overflow = true
}
// xorKeyStreamBlocks implementations expect input lengths that are a
// multiple of bufSize. Platform-specific ones process multiple blocks at a
// time, so have bufSizes that are a multiple of blockSize.
- rem := len(src) % bufSize
- full := len(src) - rem
-
+ full := len(src) - len(src)%bufSize
if full > 0 {
s.xorKeyStreamBlocks(dst[:full], src[:full])
}
+ dst, src = dst[full:], src[full:]
+
+ // If using a multi-block xorKeyStreamBlocks would overflow, use the generic
+ // one that does one block at a time.
+ const blocksPerBuf = bufSize / blockSize
+ if uint64(s.counter)+blocksPerBuf > 1<<32 {
+ s.buf = [bufSize]byte{}
+ numBlocks := (len(src) + blockSize - 1) / blockSize
+ buf := s.buf[bufSize-numBlocks*blockSize:]
+ copy(buf, src)
+ s.xorKeyStreamBlocksGeneric(buf, buf)
+ s.len = len(buf) - copy(dst, buf)
+ return
+ }
// If we have a partial (multi-)block, pad it for xorKeyStreamBlocks, and
// keep the leftover keystream for the next XORKeyStream invocation.
- if rem > 0 {
+ if len(src) > 0 {
s.buf = [bufSize]byte{}
- copy(s.buf[:], src[full:])
+ copy(s.buf[:], src)
s.xorKeyStreamBlocks(s.buf[:], s.buf[:])
- s.len = bufSize - copy(dst[full:], s.buf[:])
+ s.len = bufSize - copy(dst, s.buf[:])
}
}
@@ -260,7 +286,9 @@ func (s *Cipher) xorKeyStreamBlocksGeneric(dst, src []byte) {
s.precompDone = true
}
- for i := 0; i < len(src); i += blockSize {
+ // A condition of len(src) > 0 would be sufficient, but this also
+ // acts as a bounds check elimination hint.
+ for len(src) >= 64 && len(dst) >= 64 {
// The remainder of the first column round.
fcr0, fcr4, fcr8, fcr12 := quarterRound(c0, c4, c8, s.counter)
@@ -285,49 +313,28 @@ func (s *Cipher) xorKeyStreamBlocksGeneric(dst, src []byte) {
x3, x4, x9, x14 = quarterRound(x3, x4, x9, x14)
}
- // Finally, add back the initial state to generate the key stream.
- x0 += c0
- x1 += c1
- x2 += c2
- x3 += c3
- x4 += c4
- x5 += c5
- x6 += c6
- x7 += c7
- x8 += c8
- x9 += c9
- x10 += c10
- x11 += c11
- x12 += s.counter
- x13 += c13
- x14 += c14
- x15 += c15
+ // Add back the initial state to generate the key stream, then
+ // XOR the key stream with the source and write out the result.
+ addXor(dst[0:4], src[0:4], x0, c0)
+ addXor(dst[4:8], src[4:8], x1, c1)
+ addXor(dst[8:12], src[8:12], x2, c2)
+ addXor(dst[12:16], src[12:16], x3, c3)
+ addXor(dst[16:20], src[16:20], x4, c4)
+ addXor(dst[20:24], src[20:24], x5, c5)
+ addXor(dst[24:28], src[24:28], x6, c6)
+ addXor(dst[28:32], src[28:32], x7, c7)
+ addXor(dst[32:36], src[32:36], x8, c8)
+ addXor(dst[36:40], src[36:40], x9, c9)
+ addXor(dst[40:44], src[40:44], x10, c10)
+ addXor(dst[44:48], src[44:48], x11, c11)
+ addXor(dst[48:52], src[48:52], x12, s.counter)
+ addXor(dst[52:56], src[52:56], x13, c13)
+ addXor(dst[56:60], src[56:60], x14, c14)
+ addXor(dst[60:64], src[60:64], x15, c15)
s.counter += 1
- if s.counter == 0 {
- panic("chacha20: internal error: counter overflow")
- }
- in, out := src[i:], dst[i:]
- in, out = in[:blockSize], out[:blockSize] // bounds check elimination 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)
+ src, dst = src[blockSize:], dst[blockSize:]
}
}
diff --git a/vendor/golang.org/x/crypto/chacha20/xor.go b/vendor/golang.org/x/crypto/chacha20/xor.go
index 0110c986..c2d04851 100644
--- a/vendor/golang.org/x/crypto/chacha20/xor.go
+++ b/vendor/golang.org/x/crypto/chacha20/xor.go
@@ -13,10 +13,10 @@ const unaligned = runtime.GOARCH == "386" ||
runtime.GOARCH == "ppc64le" ||
runtime.GOARCH == "s390x"
-// xor reads a little endian uint32 from src, XORs it with u and
+// addXor reads a little endian uint32 from src, XORs it with (a + b) and
// places the result in little endian byte order in dst.
-func xor(dst, src []byte, u uint32) {
- _, _ = src[3], dst[3] // eliminate bounds checks
+func addXor(dst, src []byte, a, b uint32) {
+ _, _ = src[3], dst[3] // bounds check elimination hint
if unaligned {
// The compiler should optimize this code into
// 32-bit unaligned little endian loads and stores.
@@ -27,15 +27,16 @@ func xor(dst, src []byte, u uint32) {
v |= uint32(src[1]) << 8
v |= uint32(src[2]) << 16
v |= uint32(src[3]) << 24
- v ^= u
+ v ^= a + b
dst[0] = byte(v)
dst[1] = byte(v >> 8)
dst[2] = byte(v >> 16)
dst[3] = byte(v >> 24)
} else {
- dst[0] = src[0] ^ byte(u)
- dst[1] = src[1] ^ byte(u>>8)
- dst[2] = src[2] ^ byte(u>>16)
- dst[3] = src[3] ^ byte(u>>24)
+ a += b
+ dst[0] = src[0] ^ byte(a)
+ dst[1] = src[1] ^ byte(a>>8)
+ dst[2] = src[2] ^ byte(a>>16)
+ dst[3] = src[3] ^ byte(a>>24)
}
}