Imported Upstream version 2011-02-01.1upstream/2011-02-01.1

1 files changed, 73 insertions, 0 deletions

diff --git a/src/pkg/crypto/crypto.go b/src/pkg/crypto/crypto.go
new file mode 100644
index 000000000..be6b34adf
--- /dev/null
+++ b/src/pkg/crypto/crypto.go
@@ -0,0 +1,73 @@
+// Copyright 2011 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.
+
+// The crypto package collects common cryptographic constants.
+package crypto
+
+import (
+	"hash"
+)
+
+// Hash identifies a cryptographic hash function that is implemented in another
+// package.
+type Hash uint
+
+const (
+	MD4       Hash = 1 + iota // in package crypto/md4
+	MD5                       // in package crypto/md5
+	SHA1                      // in package crypto/sha1
+	SHA224                    // in package crypto/sha256
+	SHA256                    // in package crypto/sha256
+	SHA384                    // in package crypto/sha512
+	SHA512                    // in package crypto/sha512
+	MD5SHA1                   // no implementation; MD5+SHA1 used for TLS RSA
+	RIPEMD160                 // in package crypto/ripemd160
+	maxHash
+)
+
+var digestSizes = []uint8{
+	MD4:       16,
+	MD5:       16,
+	SHA1:      20,
+	SHA224:    28,
+	SHA256:    32,
+	SHA384:    48,
+	SHA512:    64,
+	MD5SHA1:   36,
+	RIPEMD160: 20,
+}
+
+// Size returns the length, in bytes, of a digest resulting from the given hash
+// function. It doesn't require that the hash function in question be linked
+// into the program.
+func (h Hash) Size() int {
+	if h > 0 && h < maxHash {
+		return int(digestSizes[h])
+	}
+	panic("crypto: Size of unknown hash function")
+}
+
+var hashes = make([]func() hash.Hash, maxHash)
+
+// New returns a new hash.Hash calculating the given hash function. If the
+// hash function is not linked into the binary, New returns nil.
+func (h Hash) New() hash.Hash {
+	if h > 0 && h < maxHash {
+		f := hashes[h]
+		if f != nil {
+			return f()
+		}
+	}
+	return nil
+}
+
+// RegisterHash registers a function that returns a new instance of the given
+// hash function. This is intended to be called from the init function in
+// packages that implement hash functions.
+func RegisterHash(h Hash, f func() hash.Hash) {
+	if h >= maxHash {
+		panic("crypto: RegisterHash of unknown hash function")
+	}
+	hashes[h] = f
+}