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. 8// 9// MD5 is cryptographically broken and should not be used for secure 10// applications. 11package md5 12 13import ( 14 "crypto" 15 "hash" 16) 17 18func init() { 19 crypto.RegisterHash(crypto.MD5, New) 20} 21 22// The size of an MD5 checksum in bytes. 23const Size = 16 24 25// The blocksize of MD5 in bytes. 26const BlockSize = 64 27 28const ( 29 chunk = 64 30 init0 = 0x67452301 31 init1 = 0xEFCDAB89 32 init2 = 0x98BADCFE 33 init3 = 0x10325476 34) 35 36// digest represents the partial evaluation of a checksum. 37type digest struct { 38 s [4]uint32 39 x [chunk]byte 40 nx int 41 len uint64 42} 43 44func (d *digest) Reset() { 45 d.s[0] = init0 46 d.s[1] = init1 47 d.s[2] = init2 48 d.s[3] = init3 49 d.nx = 0 50 d.len = 0 51} 52 53// New returns a new hash.Hash computing the MD5 checksum. 54func New() hash.Hash { 55 d := new(digest) 56 d.Reset() 57 return d 58} 59 60func (d *digest) Size() int { return Size } 61 62func (d *digest) BlockSize() int { return BlockSize } 63 64func (d *digest) Write(p []byte) (nn int, err error) { 65 nn = len(p) 66 d.len += uint64(nn) 67 if d.nx > 0 { 68 n := copy(d.x[d.nx:], p) 69 d.nx += n 70 if d.nx == chunk { 71 block(d, d.x[:]) 72 d.nx = 0 73 } 74 p = p[n:] 75 } 76 if len(p) >= chunk { 77 n := len(p) &^ (chunk - 1) 78 block(d, p[:n]) 79 p = p[n:] 80 } 81 if len(p) > 0 { 82 d.nx = copy(d.x[:], p) 83 } 84 return 85} 86 87func (d0 *digest) Sum(in []byte) []byte { 88 // Make a copy of d0 so that caller can keep writing and summing. 89 d := *d0 90 hash := d.checkSum() 91 return append(in, hash[:]...) 92} 93 94func (d *digest) checkSum() [Size]byte { 95 // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64. 96 len := d.len 97 var tmp [64]byte 98 tmp[0] = 0x80 99 if len%64 < 56 { 100 d.Write(tmp[0 : 56-len%64]) 101 } else { 102 d.Write(tmp[0 : 64+56-len%64]) 103 } 104 105 // Length in bits. 106 len <<= 3 107 for i := uint(0); i < 8; i++ { 108 tmp[i] = byte(len >> (8 * i)) 109 } 110 d.Write(tmp[0:8]) 111 112 if d.nx != 0 { 113 panic("d.nx != 0") 114 } 115 116 var digest [Size]byte 117 for i, s := range d.s { 118 digest[i*4] = byte(s) 119 digest[i*4+1] = byte(s >> 8) 120 digest[i*4+2] = byte(s >> 16) 121 digest[i*4+3] = byte(s >> 24) 122 } 123 124 return digest 125} 126 127// Sum returns the MD5 checksum of the data. 128func Sum(data []byte) [Size]byte { 129 var d digest 130 d.Reset() 131 d.Write(data) 132 return d.checkSum() 133} 134