1 files changed, 270 insertions, 0 deletions
diff --git a/src/crypto/sha256/sha256.go b/src/crypto/sha256/sha256.go
new file mode 100644
index 0000000..659531d
--- /dev/null
+++ b/src/crypto/sha256/sha256.go
@@ -0,0 +1,270 @@
+// 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 sha256 implements the SHA224 and SHA256 hash algorithms as defined
+// in FIPS 180-4.
+package sha256
+
+import (
+	"crypto"
+	"encoding/binary"
+	"errors"
+	"hash"
+)
+
+func init() {
+	crypto.RegisterHash(crypto.SHA224, New224)
+	crypto.RegisterHash(crypto.SHA256, New)
+}
+
+// The size of a SHA256 checksum in bytes.
+const Size = 32
+
+// The size of a SHA224 checksum in bytes.
+const Size224 = 28
+
+// The blocksize of SHA256 and SHA224 in bytes.
+const BlockSize = 64
+
+const (
+	chunk     = 64
+	init0     = 0x6A09E667
+	init1     = 0xBB67AE85
+	init2     = 0x3C6EF372
+	init3     = 0xA54FF53A
+	init4     = 0x510E527F
+	init5     = 0x9B05688C
+	init6     = 0x1F83D9AB
+	init7     = 0x5BE0CD19
+	init0_224 = 0xC1059ED8
+	init1_224 = 0x367CD507
+	init2_224 = 0x3070DD17
+	init3_224 = 0xF70E5939
+	init4_224 = 0xFFC00B31
+	init5_224 = 0x68581511
+	init6_224 = 0x64F98FA7
+	init7_224 = 0xBEFA4FA4
+)
+
+// digest represents the partial evaluation of a checksum.
+type digest struct {
+	h     [8]uint32
+	x     [chunk]byte
+	nx    int
+	len   uint64
+	is224 bool // mark if this digest is SHA-224
+}
+
+const (
+	magic224      = "sha\x02"
+	magic256      = "sha\x03"
+	marshaledSize = len(magic256) + 8*4 + chunk + 8
+)
+
+func (d *digest) MarshalBinary() ([]byte, error) {
+	b := make([]byte, 0, marshaledSize)
+	if d.is224 {
+		b = append(b, magic224...)
+	} else {
+		b = append(b, magic256...)
+	}
+	b = appendUint32(b, d.h[0])
+	b = appendUint32(b, d.h[1])
+	b = appendUint32(b, d.h[2])
+	b = appendUint32(b, d.h[3])
+	b = appendUint32(b, d.h[4])
+	b = appendUint32(b, d.h[5])
+	b = appendUint32(b, d.h[6])
+	b = appendUint32(b, d.h[7])
+	b = append(b, d.x[:d.nx]...)
+	b = b[:len(b)+len(d.x)-int(d.nx)] // already zero
+	b = appendUint64(b, d.len)
+	return b, nil
+}
+
+func (d *digest) UnmarshalBinary(b []byte) error {
+	if len(b) < len(magic224) || (d.is224 && string(b[:len(magic224)]) != magic224) || (!d.is224 && string(b[:len(magic256)]) != magic256) {
+		return errors.New("crypto/sha256: invalid hash state identifier")
+	}
+	if len(b) != marshaledSize {
+		return errors.New("crypto/sha256: invalid hash state size")
+	}
+	b = b[len(magic224):]
+	b, d.h[0] = consumeUint32(b)
+	b, d.h[1] = consumeUint32(b)
+	b, d.h[2] = consumeUint32(b)
+	b, d.h[3] = consumeUint32(b)
+	b, d.h[4] = consumeUint32(b)
+	b, d.h[5] = consumeUint32(b)
+	b, d.h[6] = consumeUint32(b)
+	b, d.h[7] = consumeUint32(b)
+	b = b[copy(d.x[:], b):]
+	b, d.len = consumeUint64(b)
+	d.nx = int(d.len % chunk)
+	return nil
+}
+
+func appendUint64(b []byte, x uint64) []byte {
+	var a [8]byte
+	binary.BigEndian.PutUint64(a[:], x)
+	return append(b, a[:]...)
+}
+
+func appendUint32(b []byte, x uint32) []byte {
+	var a [4]byte
+	binary.BigEndian.PutUint32(a[:], x)
+	return append(b, a[:]...)
+}
+
+func consumeUint64(b []byte) ([]byte, uint64) {
+	_ = b[7]
+	x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
+		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
+	return b[8:], x
+}
+
+func consumeUint32(b []byte) ([]byte, uint32) {
+	_ = b[3]
+	x := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+	return b[4:], x
+}
+
+func (d *digest) Reset() {
+	if !d.is224 {
+		d.h[0] = init0
+		d.h[1] = init1
+		d.h[2] = init2
+		d.h[3] = init3
+		d.h[4] = init4
+		d.h[5] = init5
+		d.h[6] = init6
+		d.h[7] = init7
+	} else {
+		d.h[0] = init0_224
+		d.h[1] = init1_224
+		d.h[2] = init2_224
+		d.h[3] = init3_224
+		d.h[4] = init4_224
+		d.h[5] = init5_224
+		d.h[6] = init6_224
+		d.h[7] = init7_224
+	}
+	d.nx = 0
+	d.len = 0
+}
+
+// New returns a new hash.Hash computing the SHA256 checksum. The Hash
+// also implements encoding.BinaryMarshaler and
+// encoding.BinaryUnmarshaler to marshal and unmarshal the internal
+// state of the hash.
+func New() hash.Hash {
+	d := new(digest)
+	d.Reset()
+	return d
+}
+
+// New224 returns a new hash.Hash computing the SHA224 checksum.
+func New224() hash.Hash {
+	d := new(digest)
+	d.is224 = true
+	d.Reset()
+	return d
+}
+
+func (d *digest) Size() int {
+	if !d.is224 {
+		return Size
+	}
+	return Size224
+}
+
+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 (d *digest) Sum(in []byte) []byte {
+	// Make a copy of d so that caller can keep writing and summing.
+	d0 := *d
+	hash := d0.checkSum()
+	if d0.is224 {
+		return append(in, hash[:Size224]...)
+	}
+	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
+	binary.BigEndian.PutUint64(tmp[:], len)
+	d.Write(tmp[0:8])
+
+	if d.nx != 0 {
+		panic("d.nx != 0")
+	}
+
+	var digest [Size]byte
+
+	binary.BigEndian.PutUint32(digest[0:], d.h[0])
+	binary.BigEndian.PutUint32(digest[4:], d.h[1])
+	binary.BigEndian.PutUint32(digest[8:], d.h[2])
+	binary.BigEndian.PutUint32(digest[12:], d.h[3])
+	binary.BigEndian.PutUint32(digest[16:], d.h[4])
+	binary.BigEndian.PutUint32(digest[20:], d.h[5])
+	binary.BigEndian.PutUint32(digest[24:], d.h[6])
+	if !d.is224 {
+		binary.BigEndian.PutUint32(digest[28:], d.h[7])
+	}
+
+	return digest
+}
+
+// Sum256 returns the SHA256 checksum of the data.
+func Sum256(data []byte) [Size]byte {
+	var d digest
+	d.Reset()
+	d.Write(data)
+	return d.checkSum()
+}
+
+// Sum224 returns the SHA224 checksum of the data.
+func Sum224(data []byte) [Size224]byte {
+	var d digest
+	d.is224 = true
+	d.Reset()
+	d.Write(data)
+	sum := d.checkSum()
+	ap := (*[Size224]byte)(sum[:])
+	return *ap
+}