From 38ee83e45b4de7edf89bf9f0ef629eb4c6ad0fa8 Mon Sep 17 00:00:00 2001 From: Christopher Speller Date: Thu, 12 May 2016 23:56:07 -0400 Subject: Moving to glide --- vendor/golang.org/x/crypto/xtea/cipher.go | 82 +++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 vendor/golang.org/x/crypto/xtea/cipher.go (limited to 'vendor/golang.org/x/crypto/xtea/cipher.go') diff --git a/vendor/golang.org/x/crypto/xtea/cipher.go b/vendor/golang.org/x/crypto/xtea/cipher.go new file mode 100644 index 000000000..108b42635 --- /dev/null +++ b/vendor/golang.org/x/crypto/xtea/cipher.go @@ -0,0 +1,82 @@ +// Copyright 2009 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 xtea implements XTEA encryption, as defined in Needham and Wheeler's +// 1997 technical report, "Tea extensions." +package xtea // import "golang.org/x/crypto/xtea" + +// For details, see http://www.cix.co.uk/~klockstone/xtea.pdf + +import "strconv" + +// The XTEA block size in bytes. +const BlockSize = 8 + +// A Cipher is an instance of an XTEA cipher using a particular key. +// table contains a series of precalculated values that are used each round. +type Cipher struct { + table [64]uint32 +} + +type KeySizeError int + +func (k KeySizeError) Error() string { + return "crypto/xtea: invalid key size " + strconv.Itoa(int(k)) +} + +// NewCipher creates and returns a new Cipher. +// The key argument should be the XTEA key. +// XTEA only supports 128 bit (16 byte) keys. +func NewCipher(key []byte) (*Cipher, error) { + k := len(key) + switch k { + default: + return nil, KeySizeError(k) + case 16: + break + } + + c := new(Cipher) + initCipher(c, key) + + return c, nil +} + +// BlockSize returns the XTEA block size, 8 bytes. +// It is necessary to satisfy the Block interface in the +// package "crypto/cipher". +func (c *Cipher) BlockSize() int { return BlockSize } + +// Encrypt encrypts the 8 byte buffer src using the key and stores the result in dst. +// Note that for amounts of data larger than a block, +// it is not safe to just call Encrypt on successive blocks; +// instead, use an encryption mode like CBC (see crypto/cipher/cbc.go). +func (c *Cipher) Encrypt(dst, src []byte) { encryptBlock(c, dst, src) } + +// Decrypt decrypts the 8 byte buffer src using the key k and stores the result in dst. +func (c *Cipher) Decrypt(dst, src []byte) { decryptBlock(c, dst, src) } + +// initCipher initializes the cipher context by creating a look up table +// of precalculated values that are based on the key. +func initCipher(c *Cipher, key []byte) { + // Load the key into four uint32s + var k [4]uint32 + for i := 0; i < len(k); i++ { + j := i << 2 // Multiply by 4 + k[i] = uint32(key[j+0])<<24 | uint32(key[j+1])<<16 | uint32(key[j+2])<<8 | uint32(key[j+3]) + } + + // Precalculate the table + const delta = 0x9E3779B9 + var sum uint32 = 0 + + // Two rounds of XTEA applied per loop + for i := 0; i < numRounds; { + c.table[i] = sum + k[sum&3] + i++ + sum += delta + c.table[i] = sum + k[(sum>>11)&3] + i++ + } +} -- cgit v1.2.3-1-g7c22