/**
* Derive secret key by PBKDF2 algorithm (1000 iterations of SHA256)
*
* @param fileKey
* @param version
* @return
* @throws UnsupportedEncodingException
* @throws NoSuchAlgorithmException
*/
private static String deriveKey(@NonNull byte[] fileKey, int version)
throws UnsupportedEncodingException, NoSuchAlgorithmException {
PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(new SHA256Digest());
gen.init(fileKey, salt, ITERATION_COUNT);
byte[] keyBytes =
((KeyParameter)
gen.generateDerivedMacParameters(
version == 2 ? KEY_LENGTH * 8 : KEY_LENGTH_SHORT * 8))
.getKey();
return toHex(keyBytes);
}
/**
* Derive secret key by PBKDF2 algorithm (1000 iterations of SHA256)
*
* @param password
* @param version
* @return
* @throws UnsupportedEncodingException
* @throws NoSuchAlgorithmException
*/
private static byte[] deriveKey(@NonNull String password, int version)
throws UnsupportedEncodingException, NoSuchAlgorithmException {
PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(new SHA256Digest());
gen.init(
PBEParametersGenerator.PKCS5PasswordToUTF8Bytes(password.toCharArray()),
salt,
ITERATION_COUNT);
return ((KeyParameter)
gen.generateDerivedMacParameters(version == 2 ? KEY_LENGTH * 8 : KEY_LENGTH_SHORT * 8))
.getKey();
}
/**
* Derive initial vector by PBKDF2 algorithm (10 iterations of SHA256)
*
* @param key
* @return
* @throws UnsupportedEncodingException
*/
private static byte[] deriveIv(@NonNull byte[] key) throws UnsupportedEncodingException {
PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(new SHA256Digest());
gen.init(key, salt, 10);
return ((KeyParameter) gen.generateDerivedMacParameters(KEY_LENGTH_SHORT * 8)).getKey();
}