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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.interfaces.ECPrivateKey;
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15 import java.security.interfaces.ECPublicKey;
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16 import java.security.spec.ECParameterSpec;
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17 import java.security.spec.ECPoint;
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18 import java.security.spec.ECPublicKeySpec;
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19 import java.security.spec.InvalidKeySpecException;
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20
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21 import javax.crypto.KeyAgreement;
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22
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23 import com.trilead.ssh2.signature.ECDSASHA2Verify;
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24
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25 /**
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26 * @author kenny
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27 *
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28 */
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29 public class EcDhExchange extends GenericDhExchange {
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30 private ECPrivateKey clientPrivate;
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31 private ECPublicKey clientPublic;
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32 private ECPublicKey serverPublic;
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33
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34 @Override
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35 public void init(String name) throws IOException {
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36 final ECParameterSpec spec;
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37
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38 if ("ecdh-sha2-nistp256".equals(name)) {
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39 spec = ECDSASHA2Verify.EllipticCurves.nistp256;
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40 }
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41 else if ("ecdh-sha2-nistp384".equals(name)) {
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42 spec = ECDSASHA2Verify.EllipticCurves.nistp384;
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43 }
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44 else if ("ecdh-sha2-nistp521".equals(name)) {
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45 spec = ECDSASHA2Verify.EllipticCurves.nistp521;
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46 }
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47 else {
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48 throw new IllegalArgumentException("Unknown EC curve " + name);
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49 }
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50
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51 KeyPairGenerator kpg;
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52
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53 try {
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54 kpg = KeyPairGenerator.getInstance("EC");
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55 kpg.initialize(spec);
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56 KeyPair pair = kpg.generateKeyPair();
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57 clientPrivate = (ECPrivateKey) pair.getPrivate();
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58 clientPublic = (ECPublicKey) pair.getPublic();
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59 }
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60 catch (NoSuchAlgorithmException e) {
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61 throw(IOException) new IOException("No DH keypair generator").initCause(e);
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62 }
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63 catch (InvalidAlgorithmParameterException e) {
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64 throw(IOException) new IOException("Invalid DH parameters").initCause(e);
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65 }
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66 }
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67
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68 @Override
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69 public byte[] getE() {
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70 return ECDSASHA2Verify.encodeECPoint(clientPublic.getW(), clientPublic.getParams()
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71 .getCurve());
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72 }
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73
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74 @Override
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75 protected byte[] getServerE() {
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76 return ECDSASHA2Verify.encodeECPoint(serverPublic.getW(), serverPublic.getParams()
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77 .getCurve());
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78 }
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79
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80 @Override
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81 public void setF(byte[] f) throws IOException {
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82 if (clientPublic == null)
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83 throw new IllegalStateException("DhDsaExchange not initialized!");
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84
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85 final KeyAgreement ka;
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86
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87 try {
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88 KeyFactory kf = KeyFactory.getInstance("EC");
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89 ECParameterSpec params = clientPublic.getParams();
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90 ECPoint serverPoint = ECDSASHA2Verify.decodeECPoint(f, params.getCurve());
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91 this.serverPublic = (ECPublicKey) kf.generatePublic(new ECPublicKeySpec(serverPoint,
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92 params));
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93 ka = KeyAgreement.getInstance("ECDH");
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94 ka.init(clientPrivate);
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95 ka.doPhase(serverPublic, true);
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96 }
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97 catch (NoSuchAlgorithmException e) {
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98 throw(IOException) new IOException("No ECDH key agreement method").initCause(e);
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99 }
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100 catch (InvalidKeyException e) {
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101 throw(IOException) new IOException("Invalid ECDH key").initCause(e);
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102 }
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103 catch (InvalidKeySpecException e) {
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104 throw(IOException) new IOException("Invalid ECDH key").initCause(e);
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105 }
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106
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107 sharedSecret = new BigInteger(ka.generateSecret());
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108 }
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109
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110 @Override
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111 public String getHashAlgo() {
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112 return ECDSASHA2Verify.getDigestAlgorithmForParams(clientPublic.getParams());
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113 }
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114 }
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