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1
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2 package com.trilead.ssh2.crypto;
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3
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4 import java.io.BufferedReader;
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5 import java.io.CharArrayReader;
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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.DigestException;
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9 import java.security.KeyFactory;
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10 import java.security.KeyPair;
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11 import java.security.MessageDigest;
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12 import java.security.NoSuchAlgorithmException;
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13 import java.security.PrivateKey;
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14 import java.security.PublicKey;
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15 import java.security.spec.DSAPrivateKeySpec;
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16 import java.security.spec.DSAPublicKeySpec;
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17 import java.security.spec.ECParameterSpec;
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18 import java.security.spec.ECPoint;
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19 import java.security.spec.ECPrivateKeySpec;
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20 import java.security.spec.ECPublicKeySpec;
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21 import java.security.spec.InvalidKeySpecException;
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22 import java.security.spec.KeySpec;
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23 import java.security.spec.RSAPrivateCrtKeySpec;
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24 import java.security.spec.RSAPrivateKeySpec;
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25 import java.security.spec.RSAPublicKeySpec;
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26
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27 import com.trilead.ssh2.crypto.cipher.AES;
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28 import com.trilead.ssh2.crypto.cipher.BlockCipher;
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29 import com.trilead.ssh2.crypto.cipher.CBCMode;
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30 import com.trilead.ssh2.crypto.cipher.DES;
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31 import com.trilead.ssh2.crypto.cipher.DESede;
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32 import com.trilead.ssh2.signature.ECDSASHA2Verify;
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33
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34 /**
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35 * PEM Support.
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36 *
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37 * @author Christian Plattner, plattner@trilead.com
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38 * @version $Id: PEMDecoder.java,v 1.2 2008/04/01 12:38:09 cplattne Exp $
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39 */
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40 public class PEMDecoder {
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41 public static final int PEM_RSA_PRIVATE_KEY = 1;
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42 public static final int PEM_DSA_PRIVATE_KEY = 2;
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43 public static final int PEM_EC_PRIVATE_KEY = 3;
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44
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45 private static final int hexToInt(char c) {
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46 if ((c >= 'a') && (c <= 'f')) {
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47 return (c - 'a') + 10;
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48 }
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49
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50 if ((c >= 'A') && (c <= 'F')) {
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51 return (c - 'A') + 10;
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52 }
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53
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54 if ((c >= '0') && (c <= '9')) {
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55 return (c - '0');
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56 }
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57
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58 throw new IllegalArgumentException("Need hex char");
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59 }
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60
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61 private static byte[] hexToByteArray(String hex) {
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62 if (hex == null)
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63 throw new IllegalArgumentException("null argument");
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64
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65 if ((hex.length() % 2) != 0)
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66 throw new IllegalArgumentException("Uneven string length in hex encoding.");
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67
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68 byte decoded[] = new byte[hex.length() / 2];
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69
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70 for (int i = 0; i < decoded.length; i++) {
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71 int hi = hexToInt(hex.charAt(i * 2));
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72 int lo = hexToInt(hex.charAt((i * 2) + 1));
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73 decoded[i] = (byte)(hi * 16 + lo);
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74 }
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75
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76 return decoded;
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77 }
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78
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79 private static byte[] generateKeyFromPasswordSaltWithMD5(byte[] password, byte[] salt, int keyLen)
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80 throws IOException {
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81 if (salt.length < 8)
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82 throw new IllegalArgumentException("Salt needs to be at least 8 bytes for key generation.");
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83
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84 MessageDigest md5;
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85
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86 try {
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87 md5 = MessageDigest.getInstance("MD5");
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88 }
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89 catch (NoSuchAlgorithmException e) {
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90 throw new IllegalArgumentException("VM does not support MD5", e);
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91 }
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92
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93 byte[] key = new byte[keyLen];
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94 byte[] tmp = new byte[md5.getDigestLength()];
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95
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96 while (true) {
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97 md5.update(password, 0, password.length);
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98 md5.update(salt, 0, 8); // ARGH we only use the first 8 bytes of the
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99 // salt in this step.
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100 // This took me two hours until I got AES-xxx running.
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101 int copy = (keyLen < tmp.length) ? keyLen : tmp.length;
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102
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103 try {
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104 md5.digest(tmp, 0, tmp.length);
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105 }
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106 catch (DigestException e) {
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107 IOException ex = new IOException("could not digest password");
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108 ex.initCause(e);
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109 throw ex;
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110 }
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111
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112 System.arraycopy(tmp, 0, key, key.length - keyLen, copy);
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113 keyLen -= copy;
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114
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115 if (keyLen == 0)
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116 return key;
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117
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118 md5.update(tmp, 0, tmp.length);
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119 }
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120 }
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121
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122 private static byte[] removePadding(byte[] buff, int blockSize) throws IOException {
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123 /* Removes RFC 1423/PKCS #7 padding */
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124 int rfc_1423_padding = buff[buff.length - 1] & 0xff;
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125
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126 if ((rfc_1423_padding < 1) || (rfc_1423_padding > blockSize))
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127 throw new IOException("Decrypted PEM has wrong padding, did you specify the correct password?");
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128
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129 for (int i = 2; i <= rfc_1423_padding; i++) {
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130 if (buff[buff.length - i] != rfc_1423_padding)
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131 throw new IOException("Decrypted PEM has wrong padding, did you specify the correct password?");
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132 }
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133
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134 byte[] tmp = new byte[buff.length - rfc_1423_padding];
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135 System.arraycopy(buff, 0, tmp, 0, buff.length - rfc_1423_padding);
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136 return tmp;
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137 }
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138
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139 public static final PEMStructure parsePEM(char[] pem) throws IOException {
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140 PEMStructure ps = new PEMStructure();
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141 String line = null;
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142 BufferedReader br = new BufferedReader(new CharArrayReader(pem));
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143 String endLine = null;
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144
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145 while (true) {
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146 line = br.readLine();
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147
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148 if (line == null)
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149 throw new IOException("Invalid PEM structure, '-----BEGIN...' missing");
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150
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151 line = line.trim();
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152
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153 if (line.startsWith("-----BEGIN DSA PRIVATE KEY-----")) {
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154 endLine = "-----END DSA PRIVATE KEY-----";
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155 ps.pemType = PEM_DSA_PRIVATE_KEY;
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156 break;
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157 }
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158
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159 if (line.startsWith("-----BEGIN RSA PRIVATE KEY-----")) {
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160 endLine = "-----END RSA PRIVATE KEY-----";
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161 ps.pemType = PEM_RSA_PRIVATE_KEY;
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162 break;
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163 }
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164
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165 if (line.startsWith("-----BEGIN EC PRIVATE KEY-----")) {
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166 endLine = "-----END EC PRIVATE KEY-----";
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167 ps.pemType = PEM_EC_PRIVATE_KEY;
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168 break;
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169 }
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170 }
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171
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172 while (true) {
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173 line = br.readLine();
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174
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175 if (line == null)
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176 throw new IOException("Invalid PEM structure, " + endLine + " missing");
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177
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178 line = line.trim();
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179 int sem_idx = line.indexOf(':');
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180
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181 if (sem_idx == -1)
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182 break;
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183
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184 String name = line.substring(0, sem_idx + 1);
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185 String value = line.substring(sem_idx + 1);
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186 String values[] = value.split(",");
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187
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188 for (int i = 0; i < values.length; i++)
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189 values[i] = values[i].trim();
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190
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191 // Proc-Type: 4,ENCRYPTED
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192 // DEK-Info: DES-EDE3-CBC,579B6BE3E5C60483
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193
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194 if ("Proc-Type:".equals(name)) {
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195 ps.procType = values;
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196 continue;
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197 }
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198
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199 if ("DEK-Info:".equals(name)) {
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200 ps.dekInfo = values;
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201 continue;
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202 }
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203
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204 /* Ignore line */
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205 }
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206
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207 StringBuffer keyData = new StringBuffer();
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208
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209 while (true) {
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210 if (line == null)
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211 throw new IOException("Invalid PEM structure, " + endLine + " missing");
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212
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213 line = line.trim();
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214
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215 if (line.startsWith(endLine))
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216 break;
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217
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218 keyData.append(line);
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219 line = br.readLine();
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220 }
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221
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222 char[] pem_chars = new char[keyData.length()];
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223 keyData.getChars(0, pem_chars.length, pem_chars, 0);
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224 ps.data = Base64.decode(pem_chars);
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225
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226 if (ps.data.length == 0)
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227 throw new IOException("Invalid PEM structure, no data available");
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228
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229 return ps;
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230 }
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231
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232 private static final void decryptPEM(PEMStructure ps, byte[] pw) throws IOException {
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233 if (ps.dekInfo == null)
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234 throw new IOException("Broken PEM, no mode and salt given, but encryption enabled");
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235
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236 if (ps.dekInfo.length != 2)
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237 throw new IOException("Broken PEM, DEK-Info is incomplete!");
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238
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239 String algo = ps.dekInfo[0];
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240 byte[] salt = hexToByteArray(ps.dekInfo[1]);
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241 BlockCipher bc = null;
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242
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243 if (algo.equals("DES-EDE3-CBC")) {
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244 DESede des3 = new DESede();
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245 des3.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 24));
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246 bc = new CBCMode(des3, salt, false);
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247 }
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248 else if (algo.equals("DES-CBC")) {
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249 DES des = new DES();
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250 des.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 8));
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251 bc = new CBCMode(des, salt, false);
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252 }
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253 else if (algo.equals("AES-128-CBC")) {
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254 AES aes = new AES();
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255 aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 16));
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256 bc = new CBCMode(aes, salt, false);
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257 }
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258 else if (algo.equals("AES-192-CBC")) {
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259 AES aes = new AES();
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260 aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 24));
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261 bc = new CBCMode(aes, salt, false);
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262 }
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263 else if (algo.equals("AES-256-CBC")) {
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264 AES aes = new AES();
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265 aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 32));
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266 bc = new CBCMode(aes, salt, false);
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267 }
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268 else {
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269 throw new IOException("Cannot decrypt PEM structure, unknown cipher " + algo);
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270 }
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271
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272 if ((ps.data.length % bc.getBlockSize()) != 0)
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273 throw new IOException("Invalid PEM structure, size of encrypted block is not a multiple of "
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274 + bc.getBlockSize());
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275
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276 /* Now decrypt the content */
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277 byte[] dz = new byte[ps.data.length];
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278
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279 for (int i = 0; i < ps.data.length / bc.getBlockSize(); i++) {
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280 bc.transformBlock(ps.data, i * bc.getBlockSize(), dz, i * bc.getBlockSize());
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281 }
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282
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283 /* Now check and remove RFC 1423/PKCS #7 padding */
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284 dz = removePadding(dz, bc.getBlockSize());
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285 ps.data = dz;
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286 ps.dekInfo = null;
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287 ps.procType = null;
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288 }
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289
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290 public static final boolean isPEMEncrypted(PEMStructure ps) throws IOException {
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291 if (ps.procType == null)
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292 return false;
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293
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294 if (ps.procType.length != 2)
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295 throw new IOException("Unknown Proc-Type field.");
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296
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297 if ("4".equals(ps.procType[0]) == false)
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298 throw new IOException("Unknown Proc-Type field (" + ps.procType[0] + ")");
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299
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300 if ("ENCRYPTED".equals(ps.procType[1]))
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301 return true;
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302
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303 return false;
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304 }
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305
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306 public static KeyPair decode(char[] pem, String password) throws IOException {
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307 PEMStructure ps = parsePEM(pem);
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308 return decode(ps, password);
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309 }
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310
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311 public static KeyPair decode(PEMStructure ps, String password) throws IOException {
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312 if (isPEMEncrypted(ps)) {
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313 if (password == null)
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314 throw new IOException("PEM is encrypted, but no password was specified");
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315
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316 decryptPEM(ps, password.getBytes("ISO-8859-1"));
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317 }
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318
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319 if (ps.pemType == PEM_DSA_PRIVATE_KEY) {
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320 SimpleDERReader dr = new SimpleDERReader(ps.data);
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321 byte[] seq = dr.readSequenceAsByteArray();
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322
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323 if (dr.available() != 0)
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324 throw new IOException("Padding in DSA PRIVATE KEY DER stream.");
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325
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326 dr.resetInput(seq);
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327 BigInteger version = dr.readInt();
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328
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329 if (version.compareTo(BigInteger.ZERO) != 0)
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330 throw new IOException("Wrong version (" + version + ") in DSA PRIVATE KEY DER stream.");
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331
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332 BigInteger p = dr.readInt();
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333 BigInteger q = dr.readInt();
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334 BigInteger g = dr.readInt();
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335 BigInteger y = dr.readInt();
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336 BigInteger x = dr.readInt();
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337
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338 if (dr.available() != 0)
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339 throw new IOException("Padding in DSA PRIVATE KEY DER stream.");
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340
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341 DSAPrivateKeySpec privSpec = new DSAPrivateKeySpec(x, p, q, g);
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342 DSAPublicKeySpec pubSpec = new DSAPublicKeySpec(y, p, q, g);
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343 return generateKeyPair("DSA", privSpec, pubSpec);
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344 }
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345
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346 if (ps.pemType == PEM_RSA_PRIVATE_KEY) {
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347 SimpleDERReader dr = new SimpleDERReader(ps.data);
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348 byte[] seq = dr.readSequenceAsByteArray();
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349
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350 if (dr.available() != 0)
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351 throw new IOException("Padding in RSA PRIVATE KEY DER stream.");
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352
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353 dr.resetInput(seq);
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354 BigInteger version = dr.readInt();
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355
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356 if ((version.compareTo(BigInteger.ZERO) != 0) && (version.compareTo(BigInteger.ONE) != 0))
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357 throw new IOException("Wrong version (" + version + ") in RSA PRIVATE KEY DER stream.");
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358
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359 BigInteger n = dr.readInt();
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360 BigInteger e = dr.readInt();
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361 BigInteger d = dr.readInt();
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362 // TODO: is this right?
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363 BigInteger primeP = dr.readInt();
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364 BigInteger primeQ = dr.readInt();
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365 BigInteger expP = dr.readInt();
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366 BigInteger expQ = dr.readInt();
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367 BigInteger coeff = dr.readInt();
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368 RSAPrivateKeySpec privSpec = new RSAPrivateCrtKeySpec(n, e, d, primeP, primeQ, expP, expQ, coeff);
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369 RSAPublicKeySpec pubSpec = new RSAPublicKeySpec(n, e);
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370 return generateKeyPair("RSA", privSpec, pubSpec);
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371 }
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372
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373 if (ps.pemType == PEM_EC_PRIVATE_KEY) {
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374 SimpleDERReader dr = new SimpleDERReader(ps.data);
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375 byte[] seq = dr.readSequenceAsByteArray();
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376
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377 if (dr.available() != 0)
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378 throw new IOException("Padding in EC PRIVATE KEY DER stream.");
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379
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380 dr.resetInput(seq);
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381 BigInteger version = dr.readInt();
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382
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383 if ((version.compareTo(BigInteger.ONE) != 0))
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384 throw new IOException("Wrong version (" + version + ") in EC PRIVATE KEY DER stream.");
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385
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386 byte[] privateBytes = dr.readOctetString();
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387 String curveOid = null;
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388 byte[] publicBytes = null;
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389
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390 while (dr.available() > 0) {
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391 int type = dr.readConstructedType();
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392 SimpleDERReader cr = dr.readConstructed();
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393
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394 switch (type) {
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395 case 0:
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396 curveOid = cr.readOid();
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397 break;
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398
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399 case 1:
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400 publicBytes = cr.readOctetString();
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401 break;
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402 }
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403 }
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404
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405 ECParameterSpec params = ECDSASHA2Verify.getCurveForOID(curveOid);
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406
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407 if (params == null)
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408 throw new IOException("invalid OID");
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409
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410 BigInteger s = new BigInteger(privateBytes);
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411 byte[] publicBytesSlice = new byte[publicBytes.length - 1];
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412 System.arraycopy(publicBytes, 1, publicBytesSlice, 0, publicBytesSlice.length);
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413 ECPoint w = ECDSASHA2Verify.decodeECPoint(publicBytesSlice, params.getCurve());
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414 ECPrivateKeySpec privSpec = new ECPrivateKeySpec(s, params);
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415 ECPublicKeySpec pubSpec = new ECPublicKeySpec(w, params);
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416 return generateKeyPair("EC", privSpec, pubSpec);
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417 }
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418
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419 throw new IOException("PEM problem: it is of unknown type");
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420 }
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421
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422 /**
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423 * Generate a {@code KeyPair} given an {@code algorithm} and {@code KeySpec}.
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424 */
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425 private static KeyPair generateKeyPair(String algorithm, KeySpec privSpec, KeySpec pubSpec)
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426 throws IOException {
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427 try {
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428 final KeyFactory kf = KeyFactory.getInstance(algorithm);
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429 final PublicKey pubKey = kf.generatePublic(pubSpec);
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430 final PrivateKey privKey = kf.generatePrivate(privSpec);
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431 return new KeyPair(pubKey, privKey);
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432 }
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433 catch (NoSuchAlgorithmException ex) {
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434 IOException ioex = new IOException();
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435 ioex.initCause(ex);
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436 throw ioex;
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437 }
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438 catch (InvalidKeySpecException ex) {
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439 IOException ioex = new IOException("invalid keyspec");
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440 ioex.initCause(ex);
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441 throw ioex;
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442 }
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443 }
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444 }
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