keccak/sponge.go

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package keccak
import "hash"
const Size = 256/8
const BlockSize = 1600/8 - Size*2
// digest implements hash.Hash
type digest struct {
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a [5][5]uint64 // a[y][x][z]
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buf [BlockSize]byte
len int
}
func New() hash.Hash {
return &digest{}
}
func (d *digest) Size() int { return Size }
func (d *digest) BlockSize() int { return BlockSize }
func (d *digest) Reset() {
*d = digest{}
}
func (d *digest) Write(b []byte) (int, error) {
written := len(b)
for len(b) > 0 {
n := copy(d.buf[d.len:], b)
d.len += n
b = b[n:]
if d.len == BlockSize {
d.flush()
}
}
return written, nil
}
func (d *digest) flush() {
b := d.buf[:]
loop:
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for y := range d.a {
for x := range d.a[0] {
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if len(b) == 0 {
break loop
}
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d.a[y][x] ^= le64dec(b)
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b = b[8:]
}
}
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d.a = keccakf(d.a)
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d.len = 0
}
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func keccakf(a [5][5]uint64) [5][5]uint64 {
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for i := 0; i < 24; i++ {
a = roundGeneric(a)
a[0][0] ^= RC[i]
}
return a
}
func (d0 *digest) Sum(b []byte) []byte {
d := *d0
d.buf[d.len] = 0x01
for i := d.len+1; i < BlockSize; i++ {
d.buf[i] = 0
}
d.buf[BlockSize-1] |= 0x80
d.flush()
b = le64enc(b, d.a[0][0])
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b = le64enc(b, d.a[0][1])
b = le64enc(b, d.a[0][2])
b = le64enc(b, d.a[0][3])
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return b
}
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func le64dec(b []byte) uint64 {
return uint64(b[0]) << 0 | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
}
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func le64enc(b []byte, x uint64) []byte {
return append(b, byte(x), byte(x>>8), byte(x>>16), byte(x>>24), byte(x>>32), byte(x>>40), byte(x>>48), byte(x>>56))
}
func (d *digest) writeByte(b byte) {
var tmp = [1]byte{b}
d.Write(tmp[:])
}