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minio/pkg/crypto/sha1/sha1.go

151 lines
3.1 KiB

/*
* Minio Cloud Storage, (C) 2015-2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// 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 of
// Golang project:
// https://github.com/golang/go/blob/master/LICENSE
// Using this part of Minio codebase under the license
// Apache License Version 2.0 with modifications
// Package sha1 implements the SHA1 hash algorithm as defined in RFC 3174.
package sha1
import "hash"
// Size - The size of a SHA1 checksum in bytes.
const Size = 20
// BlockSize - The blocksize of SHA1 in bytes.
const BlockSize = 64
const (
chunk = 64
init0 = 0x67452301
init1 = 0xEFCDAB89
init2 = 0x98BADCFE
init3 = 0x10325476
init4 = 0xC3D2E1F0
)
// digest represents the partial evaluation of a checksum.
type digest struct {
h [5]uint32
x [chunk]byte
nx int
len uint64
}
// Reset digest
func (d *digest) Reset() {
d.h[0] = init0
d.h[1] = init1
d.h[2] = init2
d.h[3] = init3
d.h[4] = init4
d.nx = 0
d.len = 0
}
// New returns a new hash.Hash computing the SHA1 checksum.
func New() hash.Hash {
d := new(digest)
d.Reset()
return d
}
// Return output size
func (d *digest) Size() int { return Size }
// Return checksum blocksize
func (d *digest) BlockSize() int { return BlockSize }
// Write to digest
func (d *digest) Write(p []byte) (nn int, err error) {
nn = len(p)
d.len += uint64(nn)
if d.nx > 0 {
n := copy(d.x[d.nx:], p)
d.nx += n
if d.nx == chunk {
block(d, d.x[:])
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
}
// Return checksum bytes
func (d *digest) Sum(in []byte) []byte {
// Make a copy of d0 so that caller can keep writing and summing.
d0 := *d
hash := d0.checkSum()
return append(in, hash[:]...)
}
// Intermediate checksum function
func (d *digest) checkSum() [Size]byte {
len := d.len
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
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 >> (56 - 8*i))
}
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
var digest [Size]byte
for i, s := range d.h {
digest[i*4] = byte(s >> 24)
digest[i*4+1] = byte(s >> 16)
digest[i*4+2] = byte(s >> 8)
digest[i*4+3] = byte(s)
}
return digest
}
// Sum - single caller sha1 helper
func Sum(data []byte) [Size]byte {
var d digest
d.Reset()
d.Write(data)
return d.checkSum()
}