Source file src/pkg/crypto/sha1/sha1.go
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 // Package sha1 implements the SHA1 hash algorithm as defined in RFC 3174. 6 package sha1 7 8 import ( 9 "crypto" 10 "hash" 11 ) 12 13 func init() { 14 crypto.RegisterHash(crypto.SHA1, New) 15 } 16 17 // The size of a SHA1 checksum in bytes. 18 const Size = 20 19 20 // The blocksize of SHA1 in bytes. 21 const BlockSize = 64 22 23 const ( 24 _Chunk = 64 25 _Init0 = 0x67452301 26 _Init1 = 0xEFCDAB89 27 _Init2 = 0x98BADCFE 28 _Init3 = 0x10325476 29 _Init4 = 0xC3D2E1F0 30 ) 31 32 // digest represents the partial evaluation of a checksum. 33 type digest struct { 34 h [5]uint32 35 x [_Chunk]byte 36 nx int 37 len uint64 38 } 39 40 func (d *digest) Reset() { 41 d.h[0] = _Init0 42 d.h[1] = _Init1 43 d.h[2] = _Init2 44 d.h[3] = _Init3 45 d.h[4] = _Init4 46 d.nx = 0 47 d.len = 0 48 } 49 50 // New returns a new hash.Hash computing the SHA1 checksum. 51 func New() hash.Hash { 52 d := new(digest) 53 d.Reset() 54 return d 55 } 56 57 func (d *digest) Size() int { return Size } 58 59 func (d *digest) BlockSize() int { return BlockSize } 60 61 func (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 := len(p) 66 if n > _Chunk-d.nx { 67 n = _Chunk - d.nx 68 } 69 for i := 0; i < n; i++ { 70 d.x[d.nx+i] = p[i] 71 } 72 d.nx += n 73 if d.nx == _Chunk { 74 _Block(d, d.x[0:]) 75 d.nx = 0 76 } 77 p = p[n:] 78 } 79 n := _Block(d, p) 80 p = p[n:] 81 if len(p) > 0 { 82 d.nx = copy(d.x[:], p) 83 } 84 return 85 } 86 87 func (d0 *digest) Sum(in []byte) []byte { 88 // Make a copy of d0 so that caller can keep writing and summing. 89 d := *d0 90 91 // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64. 92 len := d.len 93 var tmp [64]byte 94 tmp[0] = 0x80 95 if len%64 < 56 { 96 d.Write(tmp[0 : 56-len%64]) 97 } else { 98 d.Write(tmp[0 : 64+56-len%64]) 99 } 100 101 // Length in bits. 102 len <<= 3 103 for i := uint(0); i < 8; i++ { 104 tmp[i] = byte(len >> (56 - 8*i)) 105 } 106 d.Write(tmp[0:8]) 107 108 if d.nx != 0 { 109 panic("d.nx != 0") 110 } 111 112 var digest [Size]byte 113 for i, s := range d.h { 114 digest[i*4] = byte(s >> 24) 115 digest[i*4+1] = byte(s >> 16) 116 digest[i*4+2] = byte(s >> 8) 117 digest[i*4+3] = byte(s) 118 } 119 120 return append(in, digest[:]...) 121 }