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sm3.go
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sm3.go
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/*
* Package sm3 implements the Chinese SM3 Digest Algorithm,
* according to "go/src/crypto/sha256"
* author: weizhang <d5c5ceb0@gmail.com>
* 2017.02.24
*/
package sm3
import (
"hash"
)
// The size of a SM3 checksum in bytes.
const Size = 32
// The blocksize of SM3 in bytes.
const BlockSize = 64
const (
chunk = 64
init0 = 0x7380166F
init1 = 0x4914B2B9
init2 = 0x172442D7
init3 = 0xDA8A0600
init4 = 0xA96F30BC
init5 = 0x163138AA
init6 = 0xE38DEE4D
init7 = 0xB0FB0E4E
)
// digest represents the partial evaluation of a checksum.
type digest struct {
h [8]uint32
x [chunk]byte
nx int
len uint64
}
func (d *digest) Reset() {
d.h[0] = init0
d.h[1] = init1
d.h[2] = init2
d.h[3] = init3
d.h[4] = init4
d.h[5] = init5
d.h[6] = init6
d.h[7] = init7
d.nx = 0
d.len = 0
}
// New returns a new hash.Hash computing the SM3 checksum.
func New() hash.Hash {
d := new(digest)
d.Reset()
return d
}
func (d *digest) Size() int { return Size }
func (d *digest) BlockSize() int { return BlockSize }
func (d *digest) Write(p []byte) (nn int, err error) {
nn = len(p)
d.len += uint64(nn)
if d.nx > 0 {
n := copy(d.x[d.nx:], p)
d.nx += n
if d.nx == chunk {
block(d, d.x[:])
d.nx = 0
}
p = p[n:]
}
if len(p) >= chunk {
n := len(p) &^ (chunk - 1)
block(d, p[:n])
p = p[n:]
}
if len(p) > 0 {
d.nx = copy(d.x[:], p)
}
return
}
func (d0 *digest) Sum(in []byte) []byte {
// Make a copy of d0 so that caller can keep writing and summing.
d := *d0
hash := d.checkSum()
return append(in, hash[:]...)
}
func (d *digest) checkSum() [Size]byte {
len := d.len
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
var tmp [64]byte
tmp[0] = 0x80
if len%64 < 56 {
d.Write(tmp[0 : 56-len%64])
} else {
d.Write(tmp[0 : 64+56-len%64])
}
// Length in bits.
len <<= 3
for i := uint(0); i < 8; i++ {
tmp[i] = byte(len >> (56 - 8*i))
}
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
h := d.h[:]
var digest [Size]byte
for i, s := range h {
digest[i*4] = byte(s >> 24)
digest[i*4+1] = byte(s >> 16)
digest[i*4+2] = byte(s >> 8)
digest[i*4+3] = byte(s)
}
return digest
}
// Sum returns the SM3 checksum of the data.
func Sum(data []byte) [Size]byte {
var d digest
d.Reset()
d.Write(data)
return d.checkSum()
}