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comparison src/ch/ethz/ssh2/crypto/cipher/CTRMode.java @ 273:91a31873c42a ganymed

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start conversion from trilead to ganymed
author Carl Byington <carl@five-ten-sg.com>
date Fri, 18 Jul 2014 11:21:46 -0700
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children 071eccdff8ea
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272:ce2f4e397703 273:91a31873c42a
1 /*
2 * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
3 * Please refer to the LICENSE.txt for licensing details.
4 */
5 package ch.ethz.ssh2.crypto.cipher;
6
7 /**
8 * This is CTR mode as described in draft-ietf-secsh-newmodes-XY.txt
9 *
10 * @author Christian Plattner
11 * @version 2.50, 03/15/10
12 */
13 public class CTRMode implements BlockCipher
14 {
15 byte[] X;
16 byte[] Xenc;
17
18 BlockCipher bc;
19 int blockSize;
20 boolean doEncrypt;
21
22 int count = 0;
23
24 public void init(boolean forEncryption, byte[] key)
25 {
26 }
27
28 public CTRMode(BlockCipher tc, byte[] iv, boolean doEnc) throws IllegalArgumentException
29 {
30 bc = tc;
31 blockSize = bc.getBlockSize();
32 doEncrypt = doEnc;
33
34 if (blockSize != iv.length)
35 throw new IllegalArgumentException("IV must be " + blockSize + " bytes long! (currently " + iv.length + ")");
36
37 X = new byte[blockSize];
38 Xenc = new byte[blockSize];
39
40 System.arraycopy(iv, 0, X, 0, blockSize);
41 }
42
43 public final int getBlockSize()
44 {
45 return blockSize;
46 }
47
48 public final void transformBlock(byte[] src, int srcoff, byte[] dst, int dstoff)
49 {
50 bc.transformBlock(X, 0, Xenc, 0);
51
52 for (int i = 0; i < blockSize; i++)
53 {
54 dst[dstoff + i] = (byte) (src[srcoff + i] ^ Xenc[i]);
55 }
56
57 for (int i = (blockSize - 1); i >= 0; i--)
58 {
59 X[i]++;
60 if (X[i] != 0)
61 break;
62
63 }
64 }
65 }