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1
2 package ch.ethz.ssh2.crypto;
3
4 import java.io.BufferedReader  ;
5 import java.io.CharArrayReader ;
6 import java.io.IOException ;
7 import java.math.BigInteger ;
8
9 import ch.ethz.ssh2.crypto.cipher.AES;
10 import ch.ethz.ssh2.crypto.cipher.BlockCipher;
11 import ch.ethz.ssh2.crypto.cipher.CBCMode;
12 import ch.ethz.ssh2.crypto.cipher.DES;
13 import ch.ethz.ssh2.crypto.cipher.DESede;
14 import ch.ethz.ssh2.crypto.digest.MD5;
15 import ch.ethz.ssh2.signature.DSAPrivateKey;
16 import ch.ethz.ssh2.signature.RSAPrivateKey;
17
18
24 public class PEMDecoder
25 {
26 private static final int PEM_RSA_PRIVATE_KEY = 1;
27 private static final int PEM_DSA_PRIVATE_KEY = 2;
28
29 private static final int hexToInt(char c)
30 {
31 if ((c >= 'a') && (c <= 'f'))
32 {
33 return (c - 'a') + 10;
34 }
35
36 if ((c >= 'A') && (c <= 'F'))
37 {
38 return (c - 'A') + 10;
39 }
40
41 if ((c >= '0') && (c <= '9'))
42 {
43 return (c - '0');
44 }
45
46 throw new IllegalArgumentException ("Need hex char");
47 }
48
49 private static byte[] hexToByteArray(String hex)
50 {
51 if (hex == null)
52 throw new IllegalArgumentException ("null argument");
53
54 if ((hex.length() % 2) != 0)
55 throw new IllegalArgumentException ("Uneven string length in hex encoding.");
56
57 byte decoded[] = new byte[hex.length() / 2];
58
59 for (int i = 0; i < decoded.length; i++)
60 {
61 int hi = hexToInt(hex.charAt(i * 2));
62 int lo = hexToInt(hex.charAt((i * 2) + 1));
63
64 decoded[i] = (byte) (hi * 16 + lo);
65 }
66
67 return decoded;
68 }
69
70 private static byte[] generateKeyFromPasswordSaltWithMD5(byte[] password, byte[] salt, int keyLen)
71 throws IOException
72 {
73 if (salt.length < 8)
74 throw new IllegalArgumentException ("Salt needs to be at least 8 bytes for key generation.");
75
76 MD5 md5 = new MD5();
77
78 byte[] key = new byte[keyLen];
79 byte[] tmp = new byte[md5.getDigestLength()];
80
81 while (true)
82 {
83 md5.update(password, 0, password.length);
84 md5.update(salt, 0, 8);
87 int copy = (keyLen < tmp.length) ? keyLen : tmp.length;
88
89 md5.digest(tmp, 0);
90
91 System.arraycopy(tmp, 0, key, key.length - keyLen, copy);
92
93 keyLen -= copy;
94
95 if (keyLen == 0)
96 return key;
97
98 md5.update(tmp, 0, tmp.length);
99 }
100 }
101
102 private static byte[] removePadding(byte[] buff, int blockSize) throws IOException
103 {
104
105
106 int rfc_1423_padding = buff[buff.length - 1] & 0xff;
107
108 if ((rfc_1423_padding < 1) || (rfc_1423_padding > blockSize))
109 throw new IOException ("Decrypted PEM has wrong padding, did you specify the correct password?");
110
111 for (int i = 2; i <= rfc_1423_padding; i++)
112 {
113 if (buff[buff.length - i] != rfc_1423_padding)
114 throw new IOException ("Decrypted PEM has wrong padding, did you specify the correct password?");
115 }
116
117 byte[] tmp = new byte[buff.length - rfc_1423_padding];
118 System.arraycopy(buff, 0, tmp, 0, buff.length - rfc_1423_padding);
119 return tmp;
120 }
121
122 private static final PEMStructure parsePEM(char[] pem) throws IOException
123 {
124 PEMStructure ps = new PEMStructure();
125
126 String line = null;
127
128 BufferedReader br = new BufferedReader (new CharArrayReader (pem));
129
130 String endLine = null;
131
132 while (true)
133 {
134 line = br.readLine();
135
136 if (line == null)
137 throw new IOException ("Invalid PEM structure, '-----BEGIN...' missing");
138
139 line = line.trim();
140
141 if (line.startsWith("-----BEGIN DSA PRIVATE KEY-----"))
142 {
143 endLine = "-----END DSA PRIVATE KEY-----";
144 ps.pemType = PEM_DSA_PRIVATE_KEY;
145 break;
146 }
147
148 if (line.startsWith("-----BEGIN RSA PRIVATE KEY-----"))
149 {
150 endLine = "-----END RSA PRIVATE KEY-----";
151 ps.pemType = PEM_RSA_PRIVATE_KEY;
152 break;
153 }
154 }
155
156 while (true)
157 {
158 line = br.readLine();
159
160 if (line == null)
161 throw new IOException ("Invalid PEM structure, " + endLine + " missing");
162
163 line = line.trim();
164
165 int sem_idx = line.indexOf(':');
166
167 if (sem_idx == -1)
168 break;
169
170 String name = line.substring(0, sem_idx + 1);
171 String value = line.substring(sem_idx + 1);
172
173 String values[] = value.split(",");
174
175 for (int i = 0; i < values.length; i++)
176 values[i] = values[i].trim();
177
178
181 if ("Proc-Type:".equals(name))
182 {
183 ps.procType = values;
184 continue;
185 }
186
187 if ("DEK-Info:".equals(name))
188 {
189 ps.dekInfo = values;
190 continue;
191 }
192
193 }
194
195 StringBuffer keyData = new StringBuffer ();
196
197 while (true)
198 {
199 if (line == null)
200 throw new IOException ("Invalid PEM structure, " + endLine + " missing");
201
202 line = line.trim();
203
204 if (line.startsWith(endLine))
205 break;
206
207 keyData.append(line);
208
209 line = br.readLine();
210 }
211
212 char[] pem_chars = new char[keyData.length()];
213 keyData.getChars(0, pem_chars.length, pem_chars, 0);
214
215 ps.data = Base64.decode(pem_chars);
216
217 if (ps.data.length == 0)
218 throw new IOException ("Invalid PEM structure, no data available");
219
220 return ps;
221 }
222
223 private static final void decryptPEM(PEMStructure ps, byte[] pw) throws IOException
224 {
225 if (ps.dekInfo == null)
226 throw new IOException ("Broken PEM, no mode and salt given, but encryption enabled");
227
228 if (ps.dekInfo.length != 2)
229 throw new IOException ("Broken PEM, DEK-Info is incomplete!");
230
231 String algo = ps.dekInfo[0];
232 byte[] salt = hexToByteArray(ps.dekInfo[1]);
233
234 BlockCipher bc = null;
235
236 if (algo.equals("DES-EDE3-CBC"))
237 {
238 DESede des3 = new DESede();
239 des3.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 24));
240 bc = new CBCMode(des3, salt, false);
241 }
242 else if (algo.equals("DES-CBC"))
243 {
244 DES des = new DES();
245 des.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 8));
246 bc = new CBCMode(des, salt, false);
247 }
248 else if (algo.equals("AES-128-CBC"))
249 {
250 AES aes = new AES();
251 aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 16));
252 bc = new CBCMode(aes, salt, false);
253 }
254 else if (algo.equals("AES-192-CBC"))
255 {
256 AES aes = new AES();
257 aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 24));
258 bc = new CBCMode(aes, salt, false);
259 }
260 else if (algo.equals("AES-256-CBC"))
261 {
262 AES aes = new AES();
263 aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 32));
264 bc = new CBCMode(aes, salt, false);
265 }
266 else
267 {
268 throw new IOException ("Cannot decrypt PEM structure, unknown cipher " + algo);
269 }
270
271 if ((ps.data.length % bc.getBlockSize()) != 0)
272 throw new IOException ("Invalid PEM structure, size of encrypted block is not a multiple of "
273 + bc.getBlockSize());
274
275
276
277 byte[] dz = new byte[ps.data.length];
278
279 for (int i = 0; i < ps.data.length / bc.getBlockSize(); i++)
280 {
281 bc.transformBlock(ps.data, i * bc.getBlockSize(), dz, i * bc.getBlockSize());
282 }
283
284
285
286 dz = removePadding(dz, bc.getBlockSize());
287
288 ps.data = dz;
289 ps.dekInfo = null;
290 ps.procType = null;
291 }
292
293 public static final boolean isPEMEncrypted(PEMStructure ps) throws IOException
294 {
295 if (ps.procType == null)
296 return false;
297
298 if (ps.procType.length != 2)
299 throw new IOException ("Unknown Proc-Type field.");
300
301 if ("4".equals(ps.procType[0]) == false)
302 throw new IOException ("Unknown Proc-Type field (" + ps.procType[0] + ")");
303
304 if ("ENCRYPTED".equals(ps.procType[1]))
305 return true;
306
307 return false;
308 }
309
310 public static Object decode(char[] pem, String password) throws IOException
311 {
312 PEMStructure ps = parsePEM(pem);
313
314 if (isPEMEncrypted(ps))
315 {
316 if (password == null)
317 throw new IOException ("PEM is encrypted, but no password was specified");
318
319 decryptPEM(ps, password.getBytes());
320 }
321
322 if (ps.pemType == PEM_DSA_PRIVATE_KEY)
323 {
324 SimpleDERReader dr = new SimpleDERReader(ps.data);
325
326 byte[] seq = dr.readSequenceAsByteArray();
327
328 if (dr.available() != 0)
329 throw new IOException ("Padding in DSA PRIVATE KEY DER stream.");
330
331 dr.resetInput(seq);
332
333 BigInteger version = dr.readInt();
334
335 if (version.compareTo(BigInteger.ZERO) != 0)
336 throw new IOException ("Wrong version (" + version + ") in DSA PRIVATE KEY DER stream.");
337
338 BigInteger p = dr.readInt();
339 BigInteger q = dr.readInt();
340 BigInteger g = dr.readInt();
341 BigInteger y = dr.readInt();
342 BigInteger x = dr.readInt();
343
344 if (dr.available() != 0)
345 throw new IOException ("Padding in DSA PRIVATE KEY DER stream.");
346
347 return new DSAPrivateKey(p, q, g, y, x);
348 }
349
350 if (ps.pemType == PEM_RSA_PRIVATE_KEY)
351 {
352 SimpleDERReader dr = new SimpleDERReader(ps.data);
353
354 byte[] seq = dr.readSequenceAsByteArray();
355
356 if (dr.available() != 0)
357 throw new IOException ("Padding in RSA PRIVATE KEY DER stream.");
358
359 dr.resetInput(seq);
360
361 BigInteger version = dr.readInt();
362
363 if ((version.compareTo(BigInteger.ZERO) != 0) && (version.compareTo(BigInteger.ONE) != 0))
364 throw new IOException ("Wrong version (" + version + ") in RSA PRIVATE KEY DER stream.");
365
366 BigInteger n = dr.readInt();
367 BigInteger e = dr.readInt();
368 BigInteger d = dr.readInt();
369
370 return new RSAPrivateKey(d, e, n);
371 }
372
373 throw new IOException ("PEM problem: it is of unknown type");
374 }
375
376 }
377 |
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