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Source file src/crypto/cipher/cipher.go

     1	// Copyright 2010 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	// Package cipher implements standard block cipher modes that can be wrapped
     6	// around low-level block cipher implementations.
     7	// See http://csrc.nist.gov/groups/ST/toolkit/BCM/current_modes.html
     8	// and NIST Special Publication 800-38A.
     9	package cipher
    10	
    11	// A Block represents an implementation of block cipher
    12	// using a given key. It provides the capability to encrypt
    13	// or decrypt individual blocks. The mode implementations
    14	// extend that capability to streams of blocks.
    15	type Block interface {
    16		// BlockSize returns the cipher's block size.
    17		BlockSize() int
    18	
    19		// Encrypt encrypts the first block in src into dst.
    20		// Dst and src may point at the same memory.
    21		Encrypt(dst, src []byte)
    22	
    23		// Decrypt decrypts the first block in src into dst.
    24		// Dst and src may point at the same memory.
    25		Decrypt(dst, src []byte)
    26	}
    27	
    28	// A Stream represents a stream cipher.
    29	type Stream interface {
    30		// XORKeyStream XORs each byte in the given slice with a byte from the
    31		// cipher's key stream. Dst and src may point to the same memory.
    32		// If len(dst) < len(src), XORKeyStream should panic. It is acceptable
    33		// to pass a dst bigger than src, and in that case, XORKeyStream will
    34		// only update dst[:len(src)] and will not touch the rest of dst.
    35		XORKeyStream(dst, src []byte)
    36	}
    37	
    38	// A BlockMode represents a block cipher running in a block-based mode (CBC,
    39	// ECB etc).
    40	type BlockMode interface {
    41		// BlockSize returns the mode's block size.
    42		BlockSize() int
    43	
    44		// CryptBlocks encrypts or decrypts a number of blocks. The length of
    45		// src must be a multiple of the block size. Dst and src may point to
    46		// the same memory.
    47		CryptBlocks(dst, src []byte)
    48	}
    49	
    50	// Utility routines
    51	
    52	func dup(p []byte) []byte {
    53		q := make([]byte, len(p))
    54		copy(q, p)
    55		return q
    56	}
    57	

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