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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:generate go run gen.go -full -output md5block.go
// Package md5 implements the MD5 hash algorithm as defined in RFC 1321.
//
// MD5 is cryptographically broken and should not be used for secure
// applications.
package md5
import (
"crypto"
"errors"
"hash"
)
func init() {
crypto.RegisterHash(crypto.MD5, New)
}
// The size of an MD5 checksum in bytes.
const Size = 16
// The blocksize of MD5 in bytes.
const BlockSize = 64
const (
chunk = 64
init0 = 0x67452301
init1 = 0xEFCDAB89
init2 = 0x98BADCFE
init3 = 0x10325476
)
// digest represents the partial evaluation of a checksum.
type digest struct {
s [4]uint32
x [chunk]byte
nx int
len uint64
}
func (d *digest) Reset() {
d.s[0] = init0
d.s[1] = init1
d.s[2] = init2
d.s[3] = init3
d.nx = 0
d.len = 0
}
const (
magic = "md5\x01"
marshaledSize = len(magic) + 4*4 + chunk + 8
)
func (d *digest) MarshalBinary() ([]byte, error) {
b := make([]byte, 0, marshaledSize)
b = append(b, magic...)
b = appendUint32(b, d.s[0])
b = appendUint32(b, d.s[1])
b = appendUint32(b, d.s[2])
b = appendUint32(b, d.s[3])
b = append(b, d.x[:d.nx]...)
b = b[:len(b)+len(d.x)-d.nx] // already zero
b = appendUint64(b, d.len)
return b, nil
}
func (d *digest) UnmarshalBinary(b []byte) error {
if len(b) < len(magic) || string(b[:len(magic)]) != magic {
return errors.New("crypto/md5: invalid hash state identifier")
}
if len(b) != marshaledSize {
return errors.New("crypto/md5: invalid hash state size")
}
b = b[len(magic):]
b, d.s[0] = consumeUint32(b)
b, d.s[1] = consumeUint32(b)
b, d.s[2] = consumeUint32(b)
b, d.s[3] = consumeUint32(b)
b = b[copy(d.x[:], b):]
b, d.len = consumeUint64(b)
d.nx = int(d.len) % chunk
return nil
}
func appendUint64(b []byte, x uint64) []byte {
a := [8]byte{
byte(x >> 56),
byte(x >> 48),
byte(x >> 40),
byte(x >> 32),
byte(x >> 24),
byte(x >> 16),
byte(x >> 8),
byte(x),
}
return append(b, a[:]...)
}
func appendUint32(b []byte, x uint32) []byte {
a := [4]byte{
byte(x >> 24),
byte(x >> 16),
byte(x >> 8),
byte(x),
}
return append(b, a[:]...)
}
func consumeUint64(b []byte) ([]byte, uint64) {
_ = b[7]
x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
return b[8:], x
}
func consumeUint32(b []byte) ([]byte, uint32) {
_ = b[3]
x := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
return b[4:], x
}
// New returns a new hash.Hash computing the MD5 checksum. The Hash also
// implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to
// marshal and unmarshal the internal state of the hash.
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 (d *digest) Sum(in []byte) []byte {
// Make a copy of d so that caller can keep writing and summing.
d0 := *d
hash := d0.checkSum()
return append(in, hash[:]...)
}
func (d *digest) checkSum() [Size]byte {
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
len := d.len
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 >> (8 * i))
}
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
var digest [Size]byte
for i, s := range d.s {
digest[i*4] = byte(s)
digest[i*4+1] = byte(s >> 8)
digest[i*4+2] = byte(s >> 16)
digest[i*4+3] = byte(s >> 24)
}
return digest
}
// Sum returns the MD5 checksum of the data.
func Sum(data []byte) [Size]byte {
var d digest
d.Reset()
d.Write(data)
return d.checkSum()
}