1// Copyright 2009 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5//go:generate go run gen.go -full -output md5block.go 6 7// Package md5 implements the MD5 hash algorithm as defined in RFC 1321. 8package md5 9 10import ( 11 "crypto" 12 "hash" 13) 14 15func init() { 16 crypto.RegisterHash(crypto.MD5, New) 17} 18 19// The size of an MD5 checksum in bytes. 20const Size = 16 21 22// The blocksize of MD5 in bytes. 23const BlockSize = 64 24 25const ( 26 chunk = 64 27 init0 = 0x67452301 28 init1 = 0xEFCDAB89 29 init2 = 0x98BADCFE 30 init3 = 0x10325476 31) 32 33// digest represents the partial evaluation of a checksum. 34type digest struct { 35 s [4]uint32 36 x [chunk]byte 37 nx int 38 len uint64 39} 40 41func (d *digest) Reset() { 42 d.s[0] = init0 43 d.s[1] = init1 44 d.s[2] = init2 45 d.s[3] = init3 46 d.nx = 0 47 d.len = 0 48} 49 50// New returns a new hash.Hash computing the MD5 checksum. 51func New() hash.Hash { 52 d := new(digest) 53 d.Reset() 54 return d 55} 56 57func (d *digest) Size() int { return Size } 58 59func (d *digest) BlockSize() int { return BlockSize } 60 61func (d *digest) Write(p []byte) (nn int, err error) { 62 nn = len(p) 63 d.len += uint64(nn) 64 if d.nx > 0 { 65 n := copy(d.x[d.nx:], p) 66 d.nx += n 67 if d.nx == chunk { 68 block(d, d.x[:]) 69 d.nx = 0 70 } 71 p = p[n:] 72 } 73 if len(p) >= chunk { 74 n := len(p) &^ (chunk - 1) 75 block(d, p[:n]) 76 p = p[n:] 77 } 78 if len(p) > 0 { 79 d.nx = copy(d.x[:], p) 80 } 81 return 82} 83 84func (d0 *digest) Sum(in []byte) []byte { 85 // Make a copy of d0 so that caller can keep writing and summing. 86 d := *d0 87 hash := d.checkSum() 88 return append(in, hash[:]...) 89} 90 91func (d *digest) checkSum() [Size]byte { 92 // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64. 93 len := d.len 94 var tmp [64]byte 95 tmp[0] = 0x80 96 if len%64 < 56 { 97 d.Write(tmp[0 : 56-len%64]) 98 } else { 99 d.Write(tmp[0 : 64+56-len%64]) 100 } 101 102 // Length in bits. 103 len <<= 3 104 for i := uint(0); i < 8; i++ { 105 tmp[i] = byte(len >> (8 * i)) 106 } 107 d.Write(tmp[0:8]) 108 109 if d.nx != 0 { 110 panic("d.nx != 0") 111 } 112 113 var digest [Size]byte 114 for i, s := range d.s { 115 digest[i*4] = byte(s) 116 digest[i*4+1] = byte(s >> 8) 117 digest[i*4+2] = byte(s >> 16) 118 digest[i*4+3] = byte(s >> 24) 119 } 120 121 return digest 122} 123 124// Sum returns the MD5 checksum of the data. 125func Sum(data []byte) [Size]byte { 126 var d digest 127 d.Reset() 128 d.Write(data) 129 return d.checkSum() 130} 131