public
Last active

The keystore password on Java keystore files is utterly pointless. You can reset it without knowing it, as shown by this code. Note that private keys are still secure, as far as I know. The JKS implementation is copyright Casey Marshall (rsdio@metastatic.org), and the original source is available at http://metastatic.org/source/JKS.java. I've included it in this Gist for convenience.

  • Download Gist
ChangePassword.java
Java
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
import java.util.*;
import java.io.*;
import java.security.*;
 
public class ChangePassword
{
private final static JKS j = new JKS();
 
public static void main(String[] args) throws Exception
{
if (args.length < 2)
{
System.out.println("Usage: java ChangePassword keystoreFile newKeystoreFile");
return;
}
 
String keystoreFilename = args[0];
String newFilename = args[1];
InputStream in = new FileInputStream(keystoreFilename);
String passwd = promptForPassword("keystore");
System.out.printf("Changing password on '%s', writing to '%s'...\n", keystoreFilename, newFilename);
 
j.engineLoad(in, passwd.toCharArray());
in.close();
 
passwd = promptForPassword("new keystore");
 
OutputStream out = new FileOutputStream(newFilename);
j.engineStore(out, passwd.toCharArray());
out.close();
}
 
private static String promptForPassword(String which)
{
System.out.printf("Enter %s password: ", which);
Scanner kbd = new Scanner(System.in);
return kbd.nextLine();
}
}
JKS.java
Java
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526
/* JKS.java -- implementation of the "JKS" key store.
Copyright (C) 2003 Casey Marshall <rsdio@metastatic.org>
 
Permission to use, copy, modify, distribute, and sell this software and
its documentation for any purpose is hereby granted without fee,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation. No representations are made about the
suitability of this software for any purpose. It is provided "as is"
without express or implied warranty.
 
This program was derived by reverse-engineering Sun's own
implementation, using only the public API that is available in the 1.4.1
JDK. Hence nothing in this program is, or is derived from, anything
copyrighted by Sun Microsystems. While the "Binary Evaluation License
Agreement" that the JDK is licensed under contains blanket statements
that forbid reverse-engineering (among other things), it is my position
that US copyright law does not and cannot forbid reverse-engineering of
software to produce a compatible implementation. There are, in fact,
numerous clauses in copyright law that specifically allow
reverse-engineering, and therefore I believe it is outside of Sun's
power to enforce restrictions on reverse-engineering of their software,
and it is irresponsible for them to claim they can. */
 
 
 
 
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
 
import java.security.DigestInputStream;
import java.security.DigestOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyStoreException;
import java.security.KeyStoreSpi;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.UnrecoverableKeyException;
 
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
 
import java.util.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Vector;
 
import javax.crypto.EncryptedPrivateKeyInfo;
import javax.crypto.spec.SecretKeySpec;
 
/**
* This is an implementation of Sun's proprietary key store
* algorithm, called "JKS" for "Java Key Store". This implementation was
* created entirely through reverse-engineering.
*
* <p>The format of JKS files is, from the start of the file:
*
* <ol>
* <li>Magic bytes. This is a four-byte integer, in big-endian byte
* order, equal to <code>0xFEEDFEED</code>.</li>
* <li>The version number (probably), as a four-byte integer (all
* multibyte integral types are in big-endian byte order). The current
* version number (in modern distributions of the JDK) is 2.</li>
* <li>The number of entrires in this keystore, as a four-byte
* integer. Call this value <i>n</i></li>
* <li>Then, <i>n</i> times:
* <ol>
* <li>The entry type, a four-byte int. The value 1 denotes a private
* key entry, and 2 denotes a trusted certificate.</li>
* <li>The entry's alias, formatted as strings such as those written
* by <a
* href="http://java.sun.com/j2se/1.4.1/docs/api/java/io/DataOutput.html#writeUTF(java.lang.String)">DataOutput.writeUTF(String)</a>.</li>
* <li>An eight-byte integer, representing the entry's creation date,
* in milliseconds since the epoch.
*
* <p>Then, if the entry is a private key entry:
* <ol>
* <li>The size of the encoded key as a four-byte int, then that
* number of bytes. The encoded key is the DER encoded bytes of the
* <a
* href="http://java.sun.com/j2se/1.4.1/docs/api/javax/crypto/EncryptedPrivateKeyInfo.html">EncryptedPrivateKeyInfo</a> structure (the
* encryption algorithm is discussed later).</li>
* <li>A four-byte integer, followed by that many encoded
* certificates, encoded as described in the trusted certificates
* section.</li>
* </ol>
*
* <p>Otherwise, the entry is a trusted certificate, which is encoded
* as the name of the encoding algorithm (e.g. X.509), encoded the same
* way as alias names. Then, a four-byte integer representing the size
* of the encoded certificate, then that many bytes representing the
* encoded certificate (e.g. the DER bytes in the case of X.509).
* </li>
* </ol>
* </li>
* <li>Then, the signature.</li>
* </ol>
* </ol>
* </li>
* </ol>
*
* <p>(See <a href="genkey.java">this file</a> for some idea of how I
* was able to figure out these algorithms)</p>
*
* <p>Decrypting the key works as follows:
*
* <ol>
* <li>The key length is the length of the ciphertext minus 40. The
* encrypted key, <code>ekey</code>, is the middle bytes of the
* ciphertext.</li>
* <li>Take the first 20 bytes of the encrypted key as a seed value,
* <code>K[0]</code>.</li>
* <li>Compute <code>K[1] ... K[n]</code>, where
* <code>|K[i]| = 20</code>, <code>n = ceil(|ekey| / 20)</code>, and
* <code>K[i] = SHA-1(UTF-16BE(password) + K[i-1])</code>.</li>
* <li><code>key = ekey ^ (K[1] + ... + K[n])</code>.</li>
* <li>The last 20 bytes are the checksum, computed as <code>H =
* SHA-1(UTF-16BE(password) + key)</code>. If this value does not match
* the last 20 bytes of the ciphertext, output <code>FAIL</code>. Otherwise,
* output <code>key</code>.</li>
* </ol>
*
* <p>The signature is defined as <code>SHA-1(UTF-16BE(password) +
* US_ASCII("Mighty Aphrodite") + encoded_keystore)</code> (yup, Sun
* engineers are just that clever).
*
* <p>(Above, SHA-1 denotes the secure hash algorithm, UTF-16BE the
* big-endian byte representation of a UTF-16 string, and US_ASCII the
* ASCII byte representation of the string.)
*
* <p>The source code of this class should be available in the file <a
* href="http://metastatic.org/source/JKS.java">JKS.java</a>.
*
* @author Casey Marshall (rsdio@metastatic.org)
*/
public class JKS extends KeyStoreSpi
{
 
// Constants and fields.
// ------------------------------------------------------------------------
 
/** Ah, Sun. So goddamned clever with those magic bytes. */
private static final int MAGIC = 0xFEEDFEED;
 
private static final int PRIVATE_KEY = 1;
private static final int TRUSTED_CERT = 2;
 
private final Vector aliases;
private final HashMap trustedCerts;
private final HashMap privateKeys;
private final HashMap certChains;
private final HashMap dates;
 
// Constructor.
// ------------------------------------------------------------------------
 
public JKS()
{
super();
aliases = new Vector();
trustedCerts = new HashMap();
privateKeys = new HashMap();
certChains = new HashMap();
dates = new HashMap();
 
}
 
// Instance methods.
// ------------------------------------------------------------------------
 
public Key engineGetKey(String alias, char[] password)
throws NoSuchAlgorithmException, UnrecoverableKeyException
{
if (!privateKeys.containsKey(alias))
return null;
byte[] key = decryptKey((byte[]) privateKeys.get(alias),
charsToBytes(password));
Certificate[] chain = engineGetCertificateChain(alias);
if (chain.length > 0)
{
try
{
// Private and public keys MUST have the same algorithm.
KeyFactory fact = KeyFactory.getInstance(
chain[0].getPublicKey().getAlgorithm());
return fact.generatePrivate(new PKCS8EncodedKeySpec(key));
}
catch (InvalidKeySpecException x)
{
throw new UnrecoverableKeyException(x.getMessage());
}
}
else
return new SecretKeySpec(key, alias);
}
 
public Certificate[] engineGetCertificateChain(String alias)
{
return (Certificate[]) certChains.get(alias);
}
 
public Certificate engineGetCertificate(String alias)
{
return (Certificate) trustedCerts.get(alias);
}
 
public Date engineGetCreationDate(String alias)
{
return (Date) dates.get(alias);
}
 
// XXX implement writing methods.
 
public void engineSetKeyEntry(String alias, Key key, char[] passwd, Certificate[] certChain)
throws KeyStoreException
{
if (trustedCerts.containsKey(alias))
throw new KeyStoreException("\"" + alias + " is a trusted certificate entry");
privateKeys.put(alias, encryptKey(key, charsToBytes(passwd)));
if (certChain != null)
certChains.put(alias, certChain);
else
certChains.put(alias, new Certificate[0]);
if (!aliases.contains(alias))
{
dates.put(alias, new Date());
aliases.add(alias);
}
}
 
public void engineSetKeyEntry(String alias, byte[] encodedKey, Certificate[] certChain)
throws KeyStoreException
{
if (trustedCerts.containsKey(alias))
throw new KeyStoreException("\"" + alias + "\" is a trusted certificate entry");
try
{
new EncryptedPrivateKeyInfo(encodedKey);
}
catch (IOException ioe)
{
throw new KeyStoreException("encoded key is not an EncryptedPrivateKeyInfo");
}
privateKeys.put(alias, encodedKey);
if (certChain != null)
certChains.put(alias, certChain);
else
certChains.put(alias, new Certificate[0]);
if (!aliases.contains(alias))
{
dates.put(alias, new Date());
aliases.add(alias);
}
}
 
public void engineSetCertificateEntry(String alias, Certificate cert)
throws KeyStoreException
{
if (privateKeys.containsKey(alias))
throw new KeyStoreException("\"" + alias + "\" is a private key entry");
if (cert == null)
throw new NullPointerException();
trustedCerts.put(alias, cert);
if (!aliases.contains(alias))
{
dates.put(alias, new Date());
aliases.add(alias);
}
}
 
public void engineDeleteEntry(String alias) throws KeyStoreException
{
aliases.remove(alias);
}
 
public Enumeration engineAliases()
{
return aliases.elements();
}
 
public boolean engineContainsAlias(String alias)
{
return aliases.contains(alias);
}
 
public int engineSize()
{
return aliases.size();
}
 
public boolean engineIsKeyEntry(String alias)
{
return privateKeys.containsKey(alias);
}
 
public boolean engineIsCertificateEntry(String alias)
{
return trustedCerts.containsKey(alias);
}
 
public String engineGetCertificateAlias(Certificate cert)
{
for (Iterator keys = trustedCerts.keySet().iterator(); keys.hasNext(); )
{
String alias = (String) keys.next();
if (cert.equals(trustedCerts.get(alias)))
return alias;
}
return null;
}
 
public void engineStore(OutputStream out, char[] passwd)
throws IOException, NoSuchAlgorithmException, CertificateException
{
MessageDigest md = MessageDigest.getInstance("SHA1");
md.update(charsToBytes(passwd));
md.update("Mighty Aphrodite".getBytes("UTF-8"));
DataOutputStream dout = new DataOutputStream(new DigestOutputStream(out, md));
dout.writeInt(MAGIC);
dout.writeInt(2);
dout.writeInt(aliases.size());
for (Enumeration e = aliases.elements(); e.hasMoreElements(); )
{
String alias = (String) e.nextElement();
if (trustedCerts.containsKey(alias))
{
dout.writeInt(TRUSTED_CERT);
dout.writeUTF(alias);
dout.writeLong(((Date) dates.get(alias)).getTime());
writeCert(dout, (Certificate) trustedCerts.get(alias));
}
else
{
dout.writeInt(PRIVATE_KEY);
dout.writeUTF(alias);
dout.writeLong(((Date) dates.get(alias)).getTime());
byte[] key = (byte[]) privateKeys.get(alias);
dout.writeInt(key.length);
dout.write(key);
Certificate[] chain = (Certificate[]) certChains.get(alias);
dout.writeInt(chain.length);
for (int i = 0; i < chain.length; i++)
writeCert(dout, chain[i]);
}
}
byte[] digest = md.digest();
dout.write(digest);
}
 
public void engineLoad(InputStream in, char[] passwd)
throws IOException, NoSuchAlgorithmException, CertificateException
{
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(charsToBytes(passwd));
md.update("Mighty Aphrodite".getBytes("UTF-8")); // HAR HAR
aliases.clear();
trustedCerts.clear();
privateKeys.clear();
certChains.clear();
dates.clear();
DataInputStream din = new DataInputStream(new DigestInputStream(in, md));
if (din.readInt() != MAGIC)
throw new IOException("not a JavaKeyStore");
din.readInt(); // version no.
final int n = din.readInt();
aliases.ensureCapacity(n);
if (n < 0)
throw new IOException("negative entry count");
for (int i = 0; i < n; i++)
{
int type = din.readInt();
String alias = din.readUTF();
aliases.add(alias);
dates.put(alias, new Date(din.readLong()));
switch (type)
{
case PRIVATE_KEY:
int len = din.readInt();
byte[] encoded = new byte[len];
din.read(encoded);
privateKeys.put(alias, encoded);
int count = din.readInt();
Certificate[] chain = new Certificate[count];
for (int j = 0; j < count; j++)
chain[j] = readCert(din);
certChains.put(alias, chain);
break;
 
case TRUSTED_CERT:
trustedCerts.put(alias, readCert(din));
break;
 
default:
throw new IOException("malformed key store");
}
}
 
byte[] hash = new byte[20];
din.read(hash);
if (MessageDigest.isEqual(hash, md.digest()))
throw new IOException("signature not verified");
}
 
// Own methods.
// ------------------------------------------------------------------------
 
private static Certificate readCert(DataInputStream in)
throws IOException, CertificateException, NoSuchAlgorithmException
{
String type = in.readUTF();
int len = in.readInt();
byte[] encoded = new byte[len];
in.read(encoded);
CertificateFactory factory = CertificateFactory.getInstance(type);
return factory.generateCertificate(new ByteArrayInputStream(encoded));
}
 
private static void writeCert(DataOutputStream dout, Certificate cert)
throws IOException, CertificateException
{
dout.writeUTF(cert.getType());
byte[] b = cert.getEncoded();
dout.writeInt(b.length);
dout.write(b);
}
 
private static byte[] decryptKey(byte[] encryptedPKI, byte[] passwd)
throws UnrecoverableKeyException
{
try
{
EncryptedPrivateKeyInfo epki =
new EncryptedPrivateKeyInfo(encryptedPKI);
byte[] encr = epki.getEncryptedData();
byte[] keystream = new byte[20];
System.arraycopy(encr, 0, keystream, 0, 20);
byte[] check = new byte[20];
System.arraycopy(encr, encr.length-20, check, 0, 20);
byte[] key = new byte[encr.length - 40];
MessageDigest sha = MessageDigest.getInstance("SHA1");
int count = 0;
while (count < key.length)
{
sha.reset();
sha.update(passwd);
sha.update(keystream);
sha.digest(keystream, 0, keystream.length);
for (int i = 0; i < keystream.length && count < key.length; i++)
{
key[count] = (byte) (keystream[i] ^ encr[count+20]);
count++;
}
}
sha.reset();
sha.update(passwd);
sha.update(key);
if (!MessageDigest.isEqual(check, sha.digest()))
throw new UnrecoverableKeyException("checksum mismatch");
return key;
}
catch (Exception x)
{
throw new UnrecoverableKeyException(x.getMessage());
}
}
 
private static byte[] encryptKey(Key key, byte[] passwd)
throws KeyStoreException
{
try
{
MessageDigest sha = MessageDigest.getInstance("SHA1");
SecureRandom rand = SecureRandom.getInstance("SHA1PRNG");
byte[] k = key.getEncoded();
byte[] encrypted = new byte[k.length + 40];
byte[] keystream = rand.getSeed(20);
System.arraycopy(keystream, 0, encrypted, 0, 20);
int count = 0;
while (count < k.length)
{
sha.reset();
sha.update(passwd);
sha.update(keystream);
sha.digest(keystream, 0, keystream.length);
for (int i = 0; i < keystream.length && count < k.length; i++)
{
encrypted[count+20] = (byte) (keystream[i] ^ k[count]);
count++;
}
}
sha.reset();
sha.update(passwd);
sha.update(k);
sha.digest(encrypted, encrypted.length - 20, 20);
// 1.3.6.1.4.1.42.2.17.1.1 is Sun's private OID for this
// encryption algorithm.
return new EncryptedPrivateKeyInfo("1.3.6.1.4.1.42.2.17.1.1",
encrypted).getEncoded();
}
catch (Exception x)
{
throw new KeyStoreException(x.getMessage());
}
}
 
private static byte[] charsToBytes(char[] passwd)
{
byte[] buf = new byte[passwd.length * 2];
for (int i = 0, j = 0; i < passwd.length; i++)
{
buf[j++] = (byte) (passwd[i] >>> 8);
buf[j++] = (byte) passwd[i];
}
return buf;
}
}

How can we implement this in our project ?

Please sign in to comment on this gist.

Something went wrong with that request. Please try again.