mirror of
https://github.com/autc04/Retro68.git
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196 lines
4.5 KiB
Go
196 lines
4.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:generate go run gen.go -output md5block.go
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// Package md5 implements the MD5 hash algorithm as defined in RFC 1321.
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//
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// MD5 is cryptographically broken and should not be used for secure
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// applications.
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package md5
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import (
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"crypto"
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"encoding/binary"
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"errors"
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"hash"
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)
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func init() {
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crypto.RegisterHash(crypto.MD5, New)
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}
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// The size of an MD5 checksum in bytes.
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const Size = 16
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// The blocksize of MD5 in bytes.
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const BlockSize = 64
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const (
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init0 = 0x67452301
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init1 = 0xEFCDAB89
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init2 = 0x98BADCFE
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init3 = 0x10325476
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)
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// digest represents the partial evaluation of a checksum.
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type digest struct {
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s [4]uint32
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x [BlockSize]byte
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nx int
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len uint64
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}
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func (d *digest) Reset() {
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d.s[0] = init0
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d.s[1] = init1
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d.s[2] = init2
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d.s[3] = init3
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d.nx = 0
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d.len = 0
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}
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const (
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magic = "md5\x01"
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marshaledSize = len(magic) + 4*4 + BlockSize + 8
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)
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func (d *digest) MarshalBinary() ([]byte, error) {
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b := make([]byte, 0, marshaledSize)
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b = append(b, magic...)
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b = appendUint32(b, d.s[0])
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b = appendUint32(b, d.s[1])
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b = appendUint32(b, d.s[2])
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b = appendUint32(b, d.s[3])
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b = append(b, d.x[:d.nx]...)
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b = b[:len(b)+len(d.x)-d.nx] // already zero
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b = appendUint64(b, d.len)
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return b, nil
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}
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func (d *digest) UnmarshalBinary(b []byte) error {
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if len(b) < len(magic) || string(b[:len(magic)]) != magic {
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return errors.New("crypto/md5: invalid hash state identifier")
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}
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if len(b) != marshaledSize {
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return errors.New("crypto/md5: invalid hash state size")
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}
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b = b[len(magic):]
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b, d.s[0] = consumeUint32(b)
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b, d.s[1] = consumeUint32(b)
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b, d.s[2] = consumeUint32(b)
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b, d.s[3] = consumeUint32(b)
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b = b[copy(d.x[:], b):]
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b, d.len = consumeUint64(b)
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d.nx = int(d.len % BlockSize)
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return nil
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}
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func appendUint64(b []byte, x uint64) []byte {
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var a [8]byte
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binary.BigEndian.PutUint64(a[:], x)
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return append(b, a[:]...)
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}
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func appendUint32(b []byte, x uint32) []byte {
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var a [4]byte
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binary.BigEndian.PutUint32(a[:], x)
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return append(b, a[:]...)
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}
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func consumeUint64(b []byte) ([]byte, uint64) {
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return b[8:], binary.BigEndian.Uint64(b[0:8])
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}
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func consumeUint32(b []byte) ([]byte, uint32) {
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return b[4:], binary.BigEndian.Uint32(b[0:4])
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}
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// New returns a new hash.Hash computing the MD5 checksum. The Hash also
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// implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to
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// marshal and unmarshal the internal state of the hash.
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func New() hash.Hash {
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d := new(digest)
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d.Reset()
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return d
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}
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func (d *digest) Size() int { return Size }
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func (d *digest) BlockSize() int { return BlockSize }
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func (d *digest) Write(p []byte) (nn int, err error) {
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// Note that we currently call block or blockGeneric
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// directly (guarded using haveAsm) because this allows
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// escape analysis to see that p and d don't escape.
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nn = len(p)
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d.len += uint64(nn)
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if d.nx > 0 {
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n := copy(d.x[d.nx:], p)
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d.nx += n
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if d.nx == BlockSize {
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if haveAsm {
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block(d, d.x[:])
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} else {
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blockGeneric(d, d.x[:])
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}
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d.nx = 0
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}
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p = p[n:]
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}
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if len(p) >= BlockSize {
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n := len(p) &^ (BlockSize - 1)
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if haveAsm {
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block(d, p[:n])
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} else {
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blockGeneric(d, p[:n])
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}
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p = p[n:]
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}
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if len(p) > 0 {
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d.nx = copy(d.x[:], p)
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}
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return
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}
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func (d *digest) Sum(in []byte) []byte {
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// Make a copy of d so that caller can keep writing and summing.
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d0 := *d
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hash := d0.checkSum()
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return append(in, hash[:]...)
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}
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func (d *digest) checkSum() [Size]byte {
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// Append 0x80 to the end of the message and then append zeros
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// until the length is a multiple of 56 bytes. Finally append
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// 8 bytes representing the message length in bits.
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//
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// 1 byte end marker :: 0-63 padding bytes :: 8 byte length
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tmp := [1 + 63 + 8]byte{0x80}
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pad := (55 - d.len) % 64 // calculate number of padding bytes
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binary.LittleEndian.PutUint64(tmp[1+pad:], d.len<<3) // append length in bits
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d.Write(tmp[:1+pad+8])
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// The previous write ensures that a whole number of
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// blocks (i.e. a multiple of 64 bytes) have been hashed.
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if d.nx != 0 {
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panic("d.nx != 0")
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}
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var digest [Size]byte
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binary.LittleEndian.PutUint32(digest[0:], d.s[0])
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binary.LittleEndian.PutUint32(digest[4:], d.s[1])
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binary.LittleEndian.PutUint32(digest[8:], d.s[2])
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binary.LittleEndian.PutUint32(digest[12:], d.s[3])
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return digest
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}
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// Sum returns the MD5 checksum of the data.
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func Sum(data []byte) [Size]byte {
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var d digest
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d.Reset()
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d.Write(data)
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return d.checkSum()
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}
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