70 lines
2.5 KiB
Go
70 lines
2.5 KiB
Go
|
// 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(p []byte) []byte {
|
||
|
|
q := make([]byte, len(p))
|
||
|
|
copy(q, p)
|
||
|
|
return q
|
||
|
|
}
|