crypto: add SHA-512/224 and SHA-512/256 as described in FIPS 180-4

Change-Id: Ifbab8203dea1eb0df4c834df22e12cb7c37c14fd
Reviewed-on: https://go-review.googlesource.com/10683Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>

src/crypto/crypto.go

@@ -21,36 +21,40 @@ func (h Hash) HashFunc() Hash {
 }
 
 const (
-	MD4       Hash = 1 + iota // import golang.org/x/crypto/md4
-	MD5                       // import crypto/md5
-	SHA1                      // import crypto/sha1
-	SHA224                    // import crypto/sha256
-	SHA256                    // import crypto/sha256
-	SHA384                    // import crypto/sha512
-	SHA512                    // import crypto/sha512
-	MD5SHA1                   // no implementation; MD5+SHA1 used for TLS RSA
-	RIPEMD160                 // import golang.org/x/crypto/ripemd160
-	SHA3_224                  // import golang.org/x/crypto/sha3
-	SHA3_256                  // import golang.org/x/crypto/sha3
-	SHA3_384                  // import golang.org/x/crypto/sha3
-	SHA3_512                  // import golang.org/x/crypto/sha3
+	MD4        Hash = 1 + iota // import golang.org/x/crypto/md4
+	MD5                        // import crypto/md5
+	SHA1                       // import crypto/sha1
+	SHA224                     // import crypto/sha256
+	SHA256                     // import crypto/sha256
+	SHA384                     // import crypto/sha512
+	SHA512                     // import crypto/sha512
+	MD5SHA1                    // no implementation; MD5+SHA1 used for TLS RSA
+	RIPEMD160                  // import golang.org/x/crypto/ripemd160
+	SHA3_224                   // import golang.org/x/crypto/sha3
+	SHA3_256                   // import golang.org/x/crypto/sha3
+	SHA3_384                   // import golang.org/x/crypto/sha3
+	SHA3_512                   // import golang.org/x/crypto/sha3
+	SHA512_224                 // import crypto/sha512
+	SHA512_256                 // import crypto/sha512
 	maxHash
 )
 
 var digestSizes = []uint8{
-	MD4:       16,
-	MD5:       16,
-	SHA1:      20,
-	SHA224:    28,
-	SHA256:    32,
-	SHA384:    48,
-	SHA512:    64,
-	SHA3_224:  28,
-	SHA3_256:  32,
-	SHA3_384:  48,
-	SHA3_512:  64,
-	MD5SHA1:   36,
-	RIPEMD160: 20,
+	MD4:        16,
+	MD5:        16,
+	SHA1:       20,
+	SHA224:     28,
+	SHA256:     32,
+	SHA384:     48,
+	SHA512:     64,
+	SHA512_224: 28,
+	SHA512_256: 32,
+	SHA3_224:   28,
+	SHA3_256:   32,
+	SHA3_384:   48,
+	SHA3_512:   64,
+	MD5SHA1:    36,
+	RIPEMD160:  20,
 }
 
 // Size returns the length, in bytes, of a digest resulting from the given hash

src/crypto/sha512/sha512.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package sha512 implements the SHA384 and SHA512 hash algorithms as defined
-// in FIPS 180-2.
+// Package sha512 implements the SHA-384, SHA-512, SHA-512/224, and SHA-512/256
+// hash algorithms as defined in FIPS 180-4.
 package sha512
 
 import (
@@ -14,16 +14,27 @@ import (
 func init() {
 	crypto.RegisterHash(crypto.SHA384, New384)
 	crypto.RegisterHash(crypto.SHA512, New)
+	crypto.RegisterHash(crypto.SHA512_224, New512_224)
+	crypto.RegisterHash(crypto.SHA512_256, New512_256)
 }
 
-// The size of a SHA512 checksum in bytes.
-const Size = 64
+const (
+	// Size is the size, in bytes, of a SHA-512 checksum.
+	Size = 64
+
+	// Size224 is the size, in bytes, of a SHA-512/224 checksum.
+	Size224 = 28
+
+	// Size256 is the size, in bytes, of a SHA-512/256 checksum.
+	Size256 = 32
 
-// The size of a SHA384 checksum in bytes.
-const Size384 = 48
+	// Size384 is the size, in bytes, of a SHA-384 checksum.
+	Size384 = 48
 
-// The blocksize of SHA512 and SHA384 in bytes.
-const BlockSize = 128
+	// BlockSize is the block size, in bytes, of the SHA-512/224,
+	// SHA-512/256, SHA-384 and SHA-512 hash functions.
+	BlockSize = 128
+)
 
 const (
 	chunk     = 128
@@ -35,6 +46,22 @@ const (
 	init5     = 0x9b05688c2b3e6c1f
 	init6     = 0x1f83d9abfb41bd6b
 	init7     = 0x5be0cd19137e2179
+	init0_224 = 0x8c3d37c819544da2
+	init1_224 = 0x73e1996689dcd4d6
+	init2_224 = 0x1dfab7ae32ff9c82
+	init3_224 = 0x679dd514582f9fcf
+	init4_224 = 0x0f6d2b697bd44da8
+	init5_224 = 0x77e36f7304c48942
+	init6_224 = 0x3f9d85a86a1d36c8
+	init7_224 = 0x1112e6ad91d692a1
+	init0_256 = 0x22312194fc2bf72c
+	init1_256 = 0x9f555fa3c84c64c2
+	init2_256 = 0x2393b86b6f53b151
+	init3_256 = 0x963877195940eabd
+	init4_256 = 0x96283ee2a88effe3
+	init5_256 = 0xbe5e1e2553863992
+	init6_256 = 0x2b0199fc2c85b8aa
+	init7_256 = 0x0eb72ddc81c52ca2
 	init0_384 = 0xcbbb9d5dc1059ed8
 	init1_384 = 0x629a292a367cd507
 	init2_384 = 0x9159015a3070dd17
@@ -47,24 +74,16 @@ const (
 
 // digest represents the partial evaluation of a checksum.
 type digest struct {
-	h     [8]uint64
-	x     [chunk]byte
-	nx    int
-	len   uint64
-	is384 bool // mark if this digest is SHA-384
+	h        [8]uint64
+	x        [chunk]byte
+	nx       int
+	len      uint64
+	function crypto.Hash
 }
 
 func (d *digest) Reset() {
-	if !d.is384 {
-		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 {
+	switch d.function {
+	case crypto.SHA384:
 		d.h[0] = init0_384
 		d.h[1] = init1_384
 		d.h[2] = init2_384
@@ -73,31 +92,77 @@ func (d *digest) Reset() {
 		d.h[5] = init5_384
 		d.h[6] = init6_384
 		d.h[7] = init7_384
+	case crypto.SHA512_224:
+		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
+	case crypto.SHA512_256:
+		d.h[0] = init0_256
+		d.h[1] = init1_256
+		d.h[2] = init2_256
+		d.h[3] = init3_256
+		d.h[4] = init4_256
+		d.h[5] = init5_256
+		d.h[6] = init6_256
+		d.h[7] = init7_256
+	default:
+		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
 	}
 	d.nx = 0
 	d.len = 0
 }
 
-// New returns a new hash.Hash computing the SHA512 checksum.
+// New returns a new hash.Hash computing the SHA-512 checksum.
 func New() hash.Hash {
-	d := new(digest)
+	d := &digest{function: crypto.SHA512}
 	d.Reset()
 	return d
 }
 
-// New384 returns a new hash.Hash computing the SHA384 checksum.
+// New512_224 returns a new hash.Hash computing the SHA-512/224 checksum.
+func New512_224() hash.Hash {
+	d := &digest{function: crypto.SHA512_224}
+	d.Reset()
+	return d
+}
+
+// New512_256 returns a new hash.Hash computing the SHA-512/256 checksum.
+func New512_256() hash.Hash {
+	d := &digest{function: crypto.SHA512_256}
+	d.Reset()
+	return d
+}
+
+// New384 returns a new hash.Hash computing the SHA-384 checksum.
 func New384() hash.Hash {
-	d := new(digest)
-	d.is384 = true
+	d := &digest{function: crypto.SHA384}
 	d.Reset()
 	return d
 }
 
 func (d *digest) Size() int {
-	if !d.is384 {
+	switch d.function {
+	case crypto.SHA512_224:
+		return Size224
+	case crypto.SHA512_256:
+		return Size256
+	case crypto.SHA384:
+		return Size384
+	default:
 		return Size
 	}
-	return Size384
 }
 
 func (d *digest) BlockSize() int { return BlockSize }
@@ -130,10 +195,16 @@ func (d0 *digest) Sum(in []byte) []byte {
 	d := new(digest)
 	*d = *d0
 	hash := d.checkSum()
-	if d.is384 {
+	switch d.function {
+	case crypto.SHA384:
 		return append(in, hash[:Size384]...)
+	case crypto.SHA512_224:
+		return append(in, hash[:Size224]...)
+	case crypto.SHA512_256:
+		return append(in, hash[:Size256]...)
+	default:
+		return append(in, hash[:]...)
 	}
-	return append(in, hash[:]...)
 }
 
 func (d *digest) checkSum() [Size]byte {
@@ -159,7 +230,7 @@ func (d *digest) checkSum() [Size]byte {
 	}
 
 	h := d.h[:]
-	if d.is384 {
+	if d.function == crypto.SHA384 {
 		h = d.h[:6]
 	}
 
@@ -180,7 +251,7 @@ func (d *digest) checkSum() [Size]byte {
 
 // Sum512 returns the SHA512 checksum of the data.
 func Sum512(data []byte) [Size]byte {
-	var d digest
+	d := digest{function: crypto.SHA512}
 	d.Reset()
 	d.Write(data)
 	return d.checkSum()
@@ -188,11 +259,30 @@ func Sum512(data []byte) [Size]byte {
 
 // Sum384 returns the SHA384 checksum of the data.
 func Sum384(data []byte) (sum384 [Size384]byte) {
-	var d digest
-	d.is384 = true
+	d := digest{function: crypto.SHA384}
 	d.Reset()
 	d.Write(data)
 	sum := d.checkSum()
 	copy(sum384[:], sum[:Size384])
 	return
 }
+
+// Sum512_224 returns the Sum512/224 checksum of the data.
+func Sum512_224(data []byte) (sum224 [Size224]byte) {
+	d := digest{function: crypto.SHA512_224}
+	d.Reset()
+	d.Write(data)
+	sum := d.checkSum()
+	copy(sum224[:], sum[:Size224])
+	return
+}
+
+// Sum512_256 returns the Sum512/256 checksum of the data.
+func Sum512_256(data []byte) (sum256 [Size256]byte) {
+	d := digest{function: crypto.SHA512_256}
+	d.Reset()
+	d.Write(data)
+	sum := d.checkSum()
+	copy(sum256[:], sum[:Size256])
+	return
+}