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1
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2 package com.trilead.ssh2.crypto.cipher;
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3
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4 import java.util.Vector;
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5
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6 /**
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7 * BlockCipherFactory.
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8 *
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9 * @author Christian Plattner, plattner@trilead.com
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10 * @version $Id: BlockCipherFactory.java,v 1.2 2008/04/01 12:38:09 cplattne Exp $
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11 */
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12 public class BlockCipherFactory {
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13 static class CipherEntry {
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14 String type;
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15 int blocksize;
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16 int keysize;
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17 String cipherClass;
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18
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19 public CipherEntry(String type, int blockSize, int keySize, String cipherClass) {
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20 this.type = type;
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21 this.blocksize = blockSize;
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22 this.keysize = keySize;
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23 this.cipherClass = cipherClass;
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24 }
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25 }
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26
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27 static Vector<CipherEntry> ciphers = new Vector<CipherEntry>();
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28
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29 static {
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30 /* Higher Priority First */
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31 ciphers.addElement(new CipherEntry("aes256-ctr", 16, 32, "com.trilead.ssh2.crypto.cipher.AES"));
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32 ciphers.addElement(new CipherEntry("aes192-ctr", 16, 24, "com.trilead.ssh2.crypto.cipher.AES"));
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33 ciphers.addElement(new CipherEntry("aes128-ctr", 16, 16, "com.trilead.ssh2.crypto.cipher.AES"));
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34 ciphers.addElement(new CipherEntry("blowfish-ctr", 8, 16, "com.trilead.ssh2.crypto.cipher.BlowFish"));
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35 ciphers.addElement(new CipherEntry("aes256-cbc", 16, 32, "com.trilead.ssh2.crypto.cipher.AES"));
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36 ciphers.addElement(new CipherEntry("aes192-cbc", 16, 24, "com.trilead.ssh2.crypto.cipher.AES"));
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37 ciphers.addElement(new CipherEntry("aes128-cbc", 16, 16, "com.trilead.ssh2.crypto.cipher.AES"));
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38 ciphers.addElement(new CipherEntry("blowfish-cbc", 8, 16, "com.trilead.ssh2.crypto.cipher.BlowFish"));
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39 ciphers.addElement(new CipherEntry("3des-ctr", 8, 24, "com.trilead.ssh2.crypto.cipher.DESede"));
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40 ciphers.addElement(new CipherEntry("3des-cbc", 8, 24, "com.trilead.ssh2.crypto.cipher.DESede"));
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41 }
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42
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43 public static String[] getDefaultCipherList() {
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44 String list[] = new String[ciphers.size()];
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45
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46 for (int i = 0; i < ciphers.size(); i++) {
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47 CipherEntry ce = ciphers.elementAt(i);
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48 list[i] = new String(ce.type);
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49 }
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50
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51 return list;
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52 }
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53
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54 public static void checkCipherList(String[] cipherCandidates) {
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55 for (int i = 0; i < cipherCandidates.length; i++)
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56 getEntry(cipherCandidates[i]);
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57 }
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58
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59 public static BlockCipher createCipher(String type, boolean encrypt, byte[] key, byte[] iv) {
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60 try {
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61 CipherEntry ce = getEntry(type);
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62 Class cc = Class.forName(ce.cipherClass);
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63 BlockCipher bc = (BlockCipher) cc.newInstance();
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64
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65 if (type.endsWith("-cbc")) {
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66 bc.init(encrypt, key);
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67 return new CBCMode(bc, iv, encrypt);
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68 }
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69 else if (type.endsWith("-ctr")) {
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70 bc.init(true, key);
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71 return new CTRMode(bc, iv, encrypt);
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72 }
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73
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74 throw new IllegalArgumentException("Cannot instantiate " + type);
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75 }
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76 catch (Exception e) {
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77 throw new IllegalArgumentException("Cannot instantiate " + type);
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78 }
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79 }
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80
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81 private static CipherEntry getEntry(String type) {
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82 for (int i = 0; i < ciphers.size(); i++) {
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83 CipherEntry ce = ciphers.elementAt(i);
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84
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85 if (ce.type.equals(type))
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86 return ce;
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87 }
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88
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89 throw new IllegalArgumentException("Unkown algorithm " + type);
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90 }
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91
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92 public static int getBlockSize(String type) {
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93 CipherEntry ce = getEntry(type);
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94 return ce.blocksize;
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95 }
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96
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97 public static int getKeySize(String type) {
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98 CipherEntry ce = getEntry(type);
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99 return ce.keysize;
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100 }
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101 }
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