Imported Upstream version 1.4upstream/1.4

1 files changed, 130 insertions, 0 deletions

diff --git a/src/crypto/sha1/sha1.go b/src/crypto/sha1/sha1.go
new file mode 100644
index 000000000..9f1a96e36
--- /dev/null
+++ b/src/crypto/sha1/sha1.go
@@ -0,0 +1,130 @@
+// 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.
+
+// Package sha1 implements the SHA1 hash algorithm as defined in RFC 3174.
+package sha1
+
+import (
+	"crypto"
+	"hash"
+)
+
+func init() {
+	crypto.RegisterHash(crypto.SHA1, New)
+}
+
+// The size of a SHA1 checksum in bytes.
+const Size = 20
+
+// 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
+}
+
+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
+}
+
+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 := 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
+}
+
+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 {
+	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 returns the SHA1 checksum of the data.
+func Sum(data []byte) [Size]byte {
+	var d digest
+	d.Reset()
+	d.Write(data)
+	return d.checkSum()
+}