github.com/mangodowner/go-gm@v0.0.0-20180818020936-8baa2bd4408c/src/crypto/cipher/cipher.go (about)

     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  }