mirror of
https://github.com/golang/go
synced 2024-10-05 02:21:22 -06:00
124 lines
2.1 KiB
Go
124 lines
2.1 KiB
Go
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This package implements the SHA256 hash algorithm as defined in FIPS 180-2.
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package sha256
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import (
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"hash";
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"os";
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)
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// The size of a SHA256 checksum in bytes.
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const Size = 32
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const (
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_Chunk = 64;
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_Init0 = 0x6A09E667;
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_Init1 = 0xBB67AE85;
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_Init2 = 0x3C6EF372;
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_Init3 = 0xA54FF53A;
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_Init4 = 0x510E527F;
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_Init5 = 0x9B05688C;
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_Init6 = 0x1F83D9AB;
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_Init7 = 0x5BE0CD19;
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)
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// digest represents the partial evaluation of a checksum.
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type digest struct {
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h [8]uint32;
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x [_Chunk]byte;
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nx int;
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len uint64;
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}
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func (d *digest) Reset() {
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d.h[0] = _Init0;
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d.h[1] = _Init1;
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d.h[2] = _Init2;
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d.h[3] = _Init3;
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d.h[4] = _Init4;
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d.h[5] = _Init5;
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d.h[6] = _Init6;
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d.h[7] = _Init7;
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d.nx = 0;
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d.len = 0;
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}
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// New returns a new hash.Hash computing the SHA256 checksum.
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func New() hash.Hash {
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d := new(digest);
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d.Reset();
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return d;
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}
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func (d *digest) Size() int { return Size }
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func (d *digest) Write(p []byte) (nn int, err os.Error) {
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nn = len(p);
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d.len += uint64(nn);
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if d.nx > 0 {
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n := len(p);
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if n > _Chunk-d.nx {
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n = _Chunk - d.nx
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}
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for i := 0; i < n; i++ {
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d.x[d.nx+i] = p[i]
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}
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d.nx += n;
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if d.nx == _Chunk {
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_Block(d, &d.x);
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d.nx = 0;
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}
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p = p[n:];
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}
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n := _Block(d, p);
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p = p[n:];
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if len(p) > 0 {
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for i := 0; i < len(p); i++ {
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d.x[i] = p[i]
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}
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d.nx = len(p);
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}
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return;
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}
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func (d *digest) Sum() []byte {
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// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
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len := d.len;
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var tmp [64]byte;
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tmp[0] = 0x80;
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if len%64 < 56 {
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d.Write(tmp[0 : 56-len%64])
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} else {
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d.Write(tmp[0 : 64+56-len%64])
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}
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// Length in bits.
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len <<= 3;
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for i := uint(0); i < 8; i++ {
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tmp[i] = byte(len >> (56 - 8*i))
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}
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d.Write(tmp[0:8]);
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if d.nx != 0 {
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panicln("oops")
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}
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p := make([]byte, 32);
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j := 0;
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for i := 0; i < 8; i++ {
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s := d.h[i];
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p[j] = byte(s >> 24);
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j++;
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p[j] = byte(s >> 16);
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j++;
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p[j] = byte(s >> 8);
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j++;
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p[j] = byte(s);
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j++;
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}
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return p;
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}
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