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Source file src/crypto/cipher/cipher.go

Documentation: crypto/cipher

  // 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.
  	// 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.
  	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
  }
  

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