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1 /**
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2 *
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3 */
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4 package com.trilead.ssh2.crypto.dh;
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5
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6 import java.io.IOException;
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7 import java.math.BigInteger;
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8 import java.security.InvalidAlgorithmParameterException;
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9 import java.security.InvalidKeyException;
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10 import java.security.KeyFactory;
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11 import java.security.KeyPair;
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12 import java.security.KeyPairGenerator;
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13 import java.security.NoSuchAlgorithmException;
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14 import java.security.spec.InvalidKeySpecException;
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15
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16 import javax.crypto.KeyAgreement;
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17 import javax.crypto.interfaces.DHPrivateKey;
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18 import javax.crypto.interfaces.DHPublicKey;
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19 import javax.crypto.spec.DHParameterSpec;
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20 import javax.crypto.spec.DHPublicKeySpec;
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21
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22 /**
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23 * @author kenny
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24 *
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25 */
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26 public class DhExchange extends GenericDhExchange {
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27
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28 /* Given by the standard */
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29
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30 private static final BigInteger P1 = new BigInteger(
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31 "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1"
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32 + "29024E088A67CC74020BBEA63B139B22514A08798E3404DD"
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33 + "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245"
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34 + "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED"
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35 + "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381"
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36 + "FFFFFFFFFFFFFFFF", 16);
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37
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38 private static final BigInteger P14 = new BigInteger(
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39 "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1"
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40 + "29024E088A67CC74020BBEA63B139B22514A08798E3404DD"
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41 + "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245"
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42 + "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED"
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43 + "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D"
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44 + "C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F"
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45 + "83655D23DCA3AD961C62F356208552BB9ED529077096966D"
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46 + "670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B"
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47 + "E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9"
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48 + "DE2BCBF6955817183995497CEA956AE515D2261898FA0510"
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49 + "15728E5A8AACAA68FFFFFFFFFFFFFFFF", 16);
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50
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51 private static final BigInteger G = BigInteger.valueOf(2);
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52
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53 /* Client public and private */
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54
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55 private DHPrivateKey clientPrivate;
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56 private DHPublicKey clientPublic;
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57
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58 /* Server public */
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59
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60 private DHPublicKey serverPublic;
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61
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62 @Override
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63 public void init(String name) throws IOException {
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64 final DHParameterSpec spec;
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65
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66 if ("diffie-hellman-group1-sha1".equals(name)) {
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67 spec = new DHParameterSpec(P1, G);
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68 }
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69 else if ("diffie-hellman-group14-sha1".equals(name)) {
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70 spec = new DHParameterSpec(P14, G);
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71 }
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72 else {
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73 throw new IllegalArgumentException("Unknown DH group " + name);
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74 }
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75
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76 try {
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77 KeyPairGenerator kpg = KeyPairGenerator.getInstance("DH");
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78 kpg.initialize(spec);
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79 KeyPair pair = kpg.generateKeyPair();
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80 clientPrivate = (DHPrivateKey) pair.getPrivate();
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81 clientPublic = (DHPublicKey) pair.getPublic();
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82 }
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83 catch (NoSuchAlgorithmException e) {
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84 throw(IOException) new IOException("No DH keypair generator").initCause(e);
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85 }
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86 catch (InvalidAlgorithmParameterException e) {
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87 throw(IOException) new IOException("Invalid DH parameters").initCause(e);
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88 }
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89 }
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90
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91 @Override
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92 public byte[] getE() {
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93 if (clientPublic == null)
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94 throw new IllegalStateException("DhExchange not initialized!");
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95
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96 return clientPublic.getY().toByteArray();
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97 }
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98
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99 @Override
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100 protected byte[] getServerE() {
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101 if (serverPublic == null)
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102 throw new IllegalStateException("DhExchange not initialized!");
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103
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104 return serverPublic.getY().toByteArray();
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105 }
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106
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107 @Override
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108 public void setF(byte[] f) throws IOException {
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109 if (clientPublic == null)
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110 throw new IllegalStateException("DhExchange not initialized!");
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111
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112 final KeyAgreement ka;
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113
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114 try {
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115 KeyFactory kf = KeyFactory.getInstance("DH");
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116 DHParameterSpec params = clientPublic.getParams();
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117 this.serverPublic = (DHPublicKey) kf.generatePublic(new DHPublicKeySpec(
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118 new BigInteger(f), params.getP(), params.getG()));
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119 ka = KeyAgreement.getInstance("DH");
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120 ka.init(clientPrivate);
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121 ka.doPhase(serverPublic, true);
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122 }
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123 catch (NoSuchAlgorithmException e) {
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124 throw(IOException) new IOException("No DH key agreement method").initCause(e);
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125 }
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126 catch (InvalidKeyException e) {
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127 throw(IOException) new IOException("Invalid DH key").initCause(e);
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128 }
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129 catch (InvalidKeySpecException e) {
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130 throw(IOException) new IOException("Invalid DH key").initCause(e);
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131 }
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132
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133 sharedSecret = new BigInteger(ka.generateSecret());
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134 }
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135
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136 @Override
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137 public String getHashAlgo() {
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138 return "SHA1";
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139 }
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140 }
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