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. 11 package md5 12 13 import ( 14 "crypto" 15 "errors" 16 "hash" 17 ) 18 19 func init() { 20 crypto.RegisterHash(crypto.MD5, New) 21 } 22 23 // The size of an MD5 checksum in bytes. 24 const Size = 16 25 26 // The blocksize of MD5 in bytes. 27 const BlockSize = 64 28 29 const ( 30 chunk = 64 31 init0 = 0x67452301 32 init1 = 0xEFCDAB89 33 init2 = 0x98BADCFE 34 init3 = 0x10325476 35 ) 36 37 // digest represents the partial evaluation of a checksum. 38 type digest struct { 39 s [4]uint32 40 x [chunk]byte 41 nx int 42 len uint64 43 } 44 45 func (d *digest) Reset() { 46 d.s[0] = init0 47 d.s[1] = init1 48 d.s[2] = init2 49 d.s[3] = init3 50 d.nx = 0 51 d.len = 0 52 } 53 54 const ( 55 magic = "md5\x01" 56 marshaledSize = len(magic) + 4*4 + chunk + 8 57 ) 58 59 func (d *digest) MarshalBinary() ([]byte, error) { 60 b := make([]byte, 0, marshaledSize) 61 b = append(b, magic...) 62 b = appendUint32(b, d.s[0]) 63 b = appendUint32(b, d.s[1]) 64 b = appendUint32(b, d.s[2]) 65 b = appendUint32(b, d.s[3]) 66 b = append(b, d.x[:d.nx]...) 67 b = b[:len(b)+len(d.x)-int(d.nx)] // already zero 68 b = appendUint64(b, d.len) 69 return b, nil 70 } 71 72 func (d *digest) UnmarshalBinary(b []byte) error { 73 if len(b) < len(magic) || string(b[:len(magic)]) != magic { 74 return errors.New("crypto/md5: invalid hash state identifier") 75 } 76 if len(b) != marshaledSize { 77 return errors.New("crypto/md5: invalid hash state size") 78 } 79 b = b[len(magic):] 80 b, d.s[0] = consumeUint32(b) 81 b, d.s[1] = consumeUint32(b) 82 b, d.s[2] = consumeUint32(b) 83 b, d.s[3] = consumeUint32(b) 84 b = b[copy(d.x[:], b):] 85 b, d.len = consumeUint64(b) 86 d.nx = int(d.len) % chunk 87 return nil 88 } 89 90 func appendUint64(b []byte, x uint64) []byte { 91 a := [8]byte{ 92 byte(x >> 56), 93 byte(x >> 48), 94 byte(x >> 40), 95 byte(x >> 32), 96 byte(x >> 24), 97 byte(x >> 16), 98 byte(x >> 8), 99 byte(x), 100 } 101 return append(b, a[:]...) 102 } 103 104 func appendUint32(b []byte, x uint32) []byte { 105 a := [4]byte{ 106 byte(x >> 24), 107 byte(x >> 16), 108 byte(x >> 8), 109 byte(x), 110 } 111 return append(b, a[:]...) 112 } 113 114 func consumeUint64(b []byte) ([]byte, uint64) { 115 _ = b[7] 116 x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 | 117 uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56 118 return b[8:], x 119 } 120 121 func consumeUint32(b []byte) ([]byte, uint32) { 122 _ = b[3] 123 x := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24 124 return b[4:], x 125 } 126 127 // New returns a new hash.Hash computing the MD5 checksum. The Hash also 128 // implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to 129 // marshal and unmarshal the internal state of the hash. 130 func New() hash.Hash { 131 d := new(digest) 132 d.Reset() 133 return d 134 } 135 136 func (d *digest) Size() int { return Size } 137 138 func (d *digest) BlockSize() int { return BlockSize } 139 140 func (d *digest) Write(p []byte) (nn int, err error) { 141 nn = len(p) 142 d.len += uint64(nn) 143 if d.nx > 0 { 144 n := copy(d.x[d.nx:], p) 145 d.nx += n 146 if d.nx == chunk { 147 block(d, d.x[:]) 148 d.nx = 0 149 } 150 p = p[n:] 151 } 152 if len(p) >= chunk { 153 n := len(p) &^ (chunk - 1) 154 block(d, p[:n]) 155 p = p[n:] 156 } 157 if len(p) > 0 { 158 d.nx = copy(d.x[:], p) 159 } 160 return 161 } 162 163 func (d0 *digest) Sum(in []byte) []byte { 164 // Make a copy of d0 so that caller can keep writing and summing. 165 d := *d0 166 hash := d.checkSum() 167 return append(in, hash[:]...) 168 } 169 170 func (d *digest) checkSum() [Size]byte { 171 // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64. 172 len := d.len 173 var tmp [64]byte 174 tmp[0] = 0x80 175 if len%64 < 56 { 176 d.Write(tmp[0 : 56-len%64]) 177 } else { 178 d.Write(tmp[0 : 64+56-len%64]) 179 } 180 181 // Length in bits. 182 len <<= 3 183 for i := uint(0); i < 8; i++ { 184 tmp[i] = byte(len >> (8 * i)) 185 } 186 d.Write(tmp[0:8]) 187 188 if d.nx != 0 { 189 panic("d.nx != 0") 190 } 191 192 var digest [Size]byte 193 for i, s := range d.s { 194 digest[i*4] = byte(s) 195 digest[i*4+1] = byte(s >> 8) 196 digest[i*4+2] = byte(s >> 16) 197 digest[i*4+3] = byte(s >> 24) 198 } 199 200 return digest 201 } 202 203 // Sum returns the MD5 checksum of the data. 204 func Sum(data []byte) [Size]byte { 205 var d digest 206 d.Reset() 207 d.Write(data) 208 return d.checkSum() 209 } 210
