public void init( String pwStr, int keySize, byte[] salt, byte[] pwVerification ) throws ZipException {
	byte[] pwBytes = pwStr.getBytes();
	
	super.saltBytes = salt;

	PBEParametersGenerator generator = new PKCS5S2ParametersGenerator();
	generator.init( pwBytes, salt, ITERATION_COUNT );

	cipherParameters = generator.generateDerivedParameters(KEY_SIZE_BIT*2 + 16);
	byte[] keyBytes = ((KeyParameter)cipherParameters).getKey();

	this.cryptoKeyBytes = new byte[ KEY_SIZE_BYTE ];
	System.arraycopy( keyBytes, 0, cryptoKeyBytes, 0, KEY_SIZE_BYTE );

	this.authenticationCodeBytes = new byte[ KEY_SIZE_BYTE ];
	System.arraycopy( keyBytes, KEY_SIZE_BYTE, authenticationCodeBytes, 0, KEY_SIZE_BYTE );

	// based on SALT + PASSWORD (password is probably correct)
	this.pwVerificationBytes = new byte[ 2 ];
	System.arraycopy( keyBytes, KEY_SIZE_BYTE*2, this.pwVerificationBytes, 0, 2 );

	if( !ByteArrayHelper.isEqual( this.pwVerificationBytes, pwVerification ) ) {
		throw new ZipException("wrong password - " + ByteArrayHelper.toString(this.pwVerificationBytes) + "/ " + ByteArrayHelper.toString(pwVerification));
	}

	// create the first 16 bytes of the key sequence again (using pw+salt)
	generator.init( pwBytes, salt, ITERATION_COUNT );
	cipherParameters = generator.generateDerivedParameters(KEY_SIZE_BIT);

	// checksum added to the end of the encrypted data, update on each encryption call
	this.mac = new HMac( new SHA1Digest() );
	mac.init( new KeyParameter(authenticationCodeBytes) );

	this.aesCipher = new SICBlockCipher(new AESEngine());
	this.blockSize = aesCipher.getBlockSize();

	// incremented on each 16 byte block and used as encryption NONCE (ivBytes)
	nonce = 1;
}
 

public String encode(String password, byte[] salt, int rounds)
        throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeySpecException {
    PKCS5S2ParametersGenerator generator = new PKCS5S2ParametersGenerator();
    generator.init(PBEParametersGenerator.PKCS5PasswordToBytes(
                    password.toCharArray()),
            salt,
            rounds);
    return format("%s:%s:%d", encode(salt),
            encode(((KeyParameter)generator.generateDerivedParameters(s_keylen)).getKey()), rounds);
}
 

public static byte[] stretchPassword(char[] password, int keyLength, byte[] salt) {
	PBEParametersGenerator generator = new PKCS5S2ParametersGenerator();
	generator.init(PBEParametersGenerator.PKCS5PasswordToUTF8Bytes(password), salt, 1000);
	KeyParameter params = (KeyParameter)generator.generateDerivedParameters(keyLength);
	return params.getKey();
}
 

/**
 * Setup AES encryption based on pwBytes using WinZipAES approach
 * with SALT and pwVerification bytes based on password+salt.
 */
public void init( String pwStr, int keySize ) throws ZipException {
	byte[] pwBytes = pwStr.getBytes();
	PBEParametersGenerator generator = new PKCS5S2ParametersGenerator();
	this.saltBytes = createSalt();
	generator.init( pwBytes, saltBytes, ITERATION_COUNT );

	// create 2 byte[16] for two keys and one byte[2] for pwVerification
	// 1. encryption / 2. athentication (via HMAC/hash) /
	cipherParameters = generator.generateDerivedParameters(KEY_SIZE_BIT*2 + 16);
	byte[] keyBytes = ((KeyParameter)cipherParameters).getKey();

	this.cryptoKeyBytes = new byte[ KEY_SIZE_BYTE ];
	System.arraycopy( keyBytes, 0, cryptoKeyBytes, 0, KEY_SIZE_BYTE );

	this.authenticationCodeBytes = new byte[ KEY_SIZE_BYTE ];
	System.arraycopy( keyBytes, KEY_SIZE_BYTE, authenticationCodeBytes, 0, KEY_SIZE_BYTE );

	// based on SALT + PASSWORD (password is probably correct)
	this.pwVerificationBytes = new byte[ 2 ];
	System.arraycopy( keyBytes, KEY_SIZE_BYTE*2, pwVerificationBytes, 0, 2 );

	// create the first 16 bytes of the key sequence again (using pw+salt)
	generator.init( pwBytes, saltBytes, ITERATION_COUNT );
	cipherParameters = generator.generateDerivedParameters(KEY_SIZE_BIT);

	// checksum added to the end of the encrypted data, update on each encryption call
	this.mac = new HMac( new SHA1Digest() );
	mac.init( new KeyParameter(authenticationCodeBytes) );

	this.aesCipher = new SICBlockCipher(new AESEngine());
	this.blockSize = aesCipher.getBlockSize();

	// incremented on each 16 byte block and used as encryption NONCE (ivBytes)
	nonce = 1;
	
	if( LOG.isLoggable(Level.FINEST) ) {
		LOG.finest( "pwBytes   = " + ByteArrayHelper.toString(pwBytes) + " - " + pwBytes.length );
		LOG.finest( "salt      = " + ByteArrayHelper.toString(saltBytes) + " - " + saltBytes.length );
		LOG.finest( "pwVerif   = " + ByteArrayHelper.toString(pwVerificationBytes) + " - " + pwVerificationBytes.length );
	}
}