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Diffstat (limited to 'src/crypto/md5/md5.go')
-rw-r--r-- | src/crypto/md5/md5.go | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/crypto/md5/md5.go b/src/crypto/md5/md5.go new file mode 100644 index 000000000..8c50c6d0b --- /dev/null +++ b/src/crypto/md5/md5.go @@ -0,0 +1,136 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +//go:generate go run gen.go -full -output md5block.go + +// Package md5 implements the MD5 hash algorithm as defined in RFC 1321. +package md5 + +import ( + "crypto" + "hash" +) + +func init() { + crypto.RegisterHash(crypto.MD5, New) +} + +// The size of an MD5 checksum in bytes. +const Size = 16 + +// The blocksize of MD5 in bytes. +const BlockSize = 64 + +const ( + chunk = 64 + init0 = 0x67452301 + init1 = 0xEFCDAB89 + init2 = 0x98BADCFE + init3 = 0x10325476 +) + +// digest represents the partial evaluation of a checksum. +type digest struct { + s [4]uint32 + x [chunk]byte + nx int + len uint64 +} + +func (d *digest) Reset() { + d.s[0] = init0 + d.s[1] = init1 + d.s[2] = init2 + d.s[3] = init3 + d.nx = 0 + d.len = 0 +} + +// New returns a new hash.Hash computing the MD5 checksum. +func New() hash.Hash { + d := new(digest) + d.Reset() + return d +} + +func (d *digest) Size() int { return Size } + +func (d *digest) BlockSize() int { return BlockSize } + +func (d *digest) Write(p []byte) (nn int, err error) { + nn = len(p) + d.len += uint64(nn) + if d.nx > 0 { + n := len(p) + if n > chunk-d.nx { + n = chunk - d.nx + } + for i := 0; i < n; i++ { + d.x[d.nx+i] = p[i] + } + d.nx += n + if d.nx == chunk { + block(d, d.x[0:chunk]) + d.nx = 0 + } + p = p[n:] + } + if len(p) >= chunk { + n := len(p) &^ (chunk - 1) + block(d, p[:n]) + p = p[n:] + } + if len(p) > 0 { + d.nx = copy(d.x[:], p) + } + return +} + +func (d0 *digest) Sum(in []byte) []byte { + // Make a copy of d0 so that caller can keep writing and summing. + d := *d0 + hash := d.checkSum() + return append(in, hash[:]...) +} + +func (d *digest) checkSum() [Size]byte { + // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64. + len := d.len + var tmp [64]byte + tmp[0] = 0x80 + if len%64 < 56 { + d.Write(tmp[0 : 56-len%64]) + } else { + d.Write(tmp[0 : 64+56-len%64]) + } + + // Length in bits. + len <<= 3 + for i := uint(0); i < 8; i++ { + tmp[i] = byte(len >> (8 * i)) + } + d.Write(tmp[0:8]) + + if d.nx != 0 { + panic("d.nx != 0") + } + + var digest [Size]byte + for i, s := range d.s { + digest[i*4] = byte(s) + digest[i*4+1] = byte(s >> 8) + digest[i*4+2] = byte(s >> 16) + digest[i*4+3] = byte(s >> 24) + } + + return digest +} + +// Sum returns the MD5 checksum of the data. +func Sum(data []byte) [Size]byte { + var d digest + d.Reset() + d.Write(data) + return d.checkSum() +} |