1 files changed, 53 insertions, 0 deletions
diff --git a/src/crypto/cipher/cipher.go b/src/crypto/cipher/cipher.go
new file mode 100644
index 000000000..67afdb1e0
--- /dev/null
+++ b/src/crypto/cipher/cipher.go
@@ -0,0 +1,53 @@
+// Copyright 2010 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 cipher implements standard block cipher modes that can be wrapped
+// around low-level block cipher implementations.
+// See http://csrc.nist.gov/groups/ST/toolkit/BCM/current_modes.html
+// and NIST Special Publication 800-38A.
+package cipher
+
+// A Block represents an implementation of block cipher
+// using a given key.  It provides the capability to encrypt
+// or decrypt individual blocks.  The mode implementations
+// extend that capability to streams of blocks.
+type Block interface {
+	// BlockSize returns the cipher's block size.
+	BlockSize() int
+
+	// Encrypt encrypts the first block in src into dst.
+	// Dst and src may point at the same memory.
+	Encrypt(dst, src []byte)
+
+	// Decrypt decrypts the first block in src into dst.
+	// Dst and src may point at the same memory.
+	Decrypt(dst, src []byte)
+}
+
+// A Stream represents a stream cipher.
+type Stream interface {
+	// XORKeyStream XORs each byte in the given slice with a byte from the
+	// cipher's key stream. Dst and src may point to the same memory.
+	XORKeyStream(dst, src []byte)
+}
+
+// A BlockMode represents a block cipher running in a block-based mode (CBC,
+// ECB etc).
+type BlockMode interface {
+	// BlockSize returns the mode's block size.
+	BlockSize() int
+
+	// CryptBlocks encrypts or decrypts a number of blocks. The length of
+	// src must be a multiple of the block size. Dst and src may point to
+	// the same memory.
+	CryptBlocks(dst, src []byte)
+}
+
+// Utility routines
+
+func dup(p []byte) []byte {
+	q := make([]byte, len(p))
+	copy(q, p)
+	return q
+}