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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.
// Package md4 implements the MD4 hash algorithm as defined in RFC 1320.
//
// MD4 is cryptographically broken and should should only be used where
// compatibility with legacy systems, not security, is the goal. Instead, use a
// secure hash like SHA-256 (from crypto/sha256).
package md4
import (
"crypto"
"encoding/binary"
"hash"
)
//go:generate go run -modfile=asm/go.mod asm/asm.go -out block_amd64.s -stubs block_amd64.go -pkg md4
func init() {
crypto.RegisterHash(crypto.MD4, New)
}
// Size of an MD4 checksum in bytes.
const Size = 16
// BlockSize is the block size of MD4 in bytes.
const BlockSize = 64
const (
init0 = 0x67452301
init1 = 0xEFCDAB89
init2 = 0x98BADCFE
init3 = 0x10325476
)
// digest represents the partial evaluation of a checksum.
type digest struct {
s [4]uint32
x [BlockSize]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
}
// New returns a new hash.Hash computing the MD4 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) (int, error) {
return d.write(p), nil
}
func (d *digest) write(p []byte) int {
nn := len(p)
d.len += uint64(nn)
if d.nx > 0 {
n := len(p)
if n > BlockSize-d.nx {
n = BlockSize - d.nx
}
for i := 0; i < n; i++ {
d.x[d.nx+i] = p[i]
}
d.nx += n
if d.nx == BlockSize {
block(&d.s, d.x[0:])
d.nx = 0
}
p = p[n:]
}
for len(p) >= BlockSize {
block(&d.s, p)
p = p[BlockSize:]
}
if len(p) > 0 {
d.nx = copy(d.x[:], p)
}
return nn
}
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 {
// Append 0x80 to the end of the message and then append zeros
// until the length is a multiple of 56 bytes. Finally append
// 8 bytes representing the message length in bits.
//
// 1 byte end marker :: 0-63 padding bytes :: 8 byte length
tmp := [1 + 63 + 8]byte{0x80}
pad := (55 - d.len) % 64 // calculate number of padding bytes
binary.LittleEndian.PutUint64(tmp[1+pad:], d.len<<3) // append length in bits
d.write(tmp[:1+pad+8])
// The previous write ensures that a whole number of
// blocks (i.e. a multiple of 64 bytes) have been hashed.
if d.nx != 0 {
panic("d.nx != 0")
}
var digest [Size]byte
binary.LittleEndian.PutUint32(digest[0:], d.s[0])
binary.LittleEndian.PutUint32(digest[4:], d.s[1])
binary.LittleEndian.PutUint32(digest[8:], d.s[2])
binary.LittleEndian.PutUint32(digest[12:], d.s[3])
return digest
}
// Sum returns the MD4 checksum of the data.
func Sum(data []byte) [Size]byte {
var d digest
d.Reset()
d.write(data)
return d.checkSum()
}
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