// 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 https://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 must overlap entirely or not at all. Encrypt(dst, src []byte) // Decrypt decrypts the first block in src into dst. // Dst and src must overlap entirely or not at all. 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 must overlap entirely or not at all. // // If len(dst) < len(src), XORKeyStream should panic. It is acceptable // to pass a dst bigger than src, and in that case, XORKeyStream will // only update dst[:len(src)] and will not touch the rest of dst. // // Multiple calls to XORKeyStream behave as if the concatenation of // the src buffers was passed in a single run. That is, Stream // maintains state and does not reset at each XORKeyStream call. 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 must overlap // entirely or not at all. // // If len(dst) < len(src), CryptBlocks should panic. It is acceptable // to pass a dst bigger than src, and in that case, CryptBlocks will // only update dst[:len(src)] and will not touch the rest of dst. // // Multiple calls to CryptBlocks behave as if the concatenation of // the src buffers was passed in a single run. That is, BlockMode // maintains state and does not reset at each CryptBlocks call. CryptBlocks(dst, src []byte) } // Utility routines func dup( []byte) []byte { := make([]byte, len()) copy(, ) return }