diff options
| author | Stefan Majewsky <majewsky@gmx.net> | 2017-05-04 22:36:53 +0200 |
|---|---|---|
| committer | Stefan Majewsky <majewsky@gmx.net> | 2017-05-04 22:36:53 +0200 |
| commit | ec4270c43f1ddd37d1eb19da5db78129b93f72b7 (patch) | |
| tree | 67ab3eab1e71ef1b5479f3f5a00e040b622d7191 /vendor/golang.org/x/crypto/xtea/block.go | |
| parent | c69e9f604c47469429a6a8a27ba7ef873134e0a1 (diff) | |
| download | gofu-ec4270c43f1ddd37d1eb19da5db78129b93f72b7.tar.gz | |
add "cli" package with a Query method
Diffstat (limited to 'vendor/golang.org/x/crypto/xtea/block.go')
| -rw-r--r-- | vendor/golang.org/x/crypto/xtea/block.go | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/xtea/block.go b/vendor/golang.org/x/crypto/xtea/block.go new file mode 100644 index 0000000..bf5d245 --- /dev/null +++ b/vendor/golang.org/x/crypto/xtea/block.go @@ -0,0 +1,66 @@ +// 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. + +/* + Implementation adapted from Needham and Wheeler's paper: + http://www.cix.co.uk/~klockstone/xtea.pdf + + A precalculated look up table is used during encryption/decryption for values that are based purely on the key. +*/ + +package xtea + +// XTEA is based on 64 rounds. +const numRounds = 64 + +// blockToUint32 reads an 8 byte slice into two uint32s. +// The block is treated as big endian. +func blockToUint32(src []byte) (uint32, uint32) { + r0 := uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3]) + r1 := uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7]) + return r0, r1 +} + +// uint32ToBlock writes two uint32s into an 8 byte data block. +// Values are written as big endian. +func uint32ToBlock(v0, v1 uint32, dst []byte) { + dst[0] = byte(v0 >> 24) + dst[1] = byte(v0 >> 16) + dst[2] = byte(v0 >> 8) + dst[3] = byte(v0) + dst[4] = byte(v1 >> 24) + dst[5] = byte(v1 >> 16) + dst[6] = byte(v1 >> 8) + dst[7] = byte(v1 >> 0) +} + +// encryptBlock encrypts a single 8 byte block using XTEA. +func encryptBlock(c *Cipher, dst, src []byte) { + v0, v1 := blockToUint32(src) + + // Two rounds of XTEA applied per loop + for i := 0; i < numRounds; { + v0 += ((v1<<4 ^ v1>>5) + v1) ^ c.table[i] + i++ + v1 += ((v0<<4 ^ v0>>5) + v0) ^ c.table[i] + i++ + } + + uint32ToBlock(v0, v1, dst) +} + +// decryptBlock decrypt a single 8 byte block using XTEA. +func decryptBlock(c *Cipher, dst, src []byte) { + v0, v1 := blockToUint32(src) + + // Two rounds of XTEA applied per loop + for i := numRounds; i > 0; { + i-- + v1 -= ((v0<<4 ^ v0>>5) + v0) ^ c.table[i] + i-- + v0 -= ((v1<<4 ^ v1>>5) + v1) ^ c.table[i] + } + + uint32ToBlock(v0, v1, dst) +} |
