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/*
* Copyright 2016 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.keycloak.models.utils;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.math.BigInteger;
import java.security.SecureRandom;
/**
* @author Bill Burke
* @version $Revision: 1 $
*/
public class HmacOTP {
public static final String HMAC_SHA1 = "HmacSHA1";
public static final String HMAC_SHA256 = "HmacSHA256";
public static final String HMAC_SHA512 = "HmacSHA512";
public static final String DEFAULT_ALGORITHM = HMAC_SHA1;
public static final int DEFAULT_NUMBER_DIGITS = 6;
// 0 1 2 3 4 5 6 7 8
private static final int[] DIGITS_POWER = {1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000};
protected final String algorithm;
protected final int numberDigits;
protected final int lookAheadWindow;
public HmacOTP(int numberDigits, String algorithm, int delayWindow) {
this.numberDigits = numberDigits;
this.algorithm = algorithm;
this.lookAheadWindow = delayWindow;
}
public static String generateSecret(int length) {
String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVW1234567890";
SecureRandom r = new SecureRandom();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
char c = chars.charAt(r.nextInt(chars.length()));
sb.append(c);
}
return sb.toString();
}
public String generateHOTP(String key, int counter) {
String steps = Integer.toHexString(counter).toUpperCase();
// Just get a 16 digit string
while (steps.length() < 16)
steps = "0" + steps;
return generateOTP(key, steps, numberDigits, algorithm);
}
/**
*
* @param token
* @param key
* @param counter
* @return -1 if not a match. A positive number means successful validation. This positive number is also the new value of the counter
*/
public int validateHOTP(String token, String key, int counter) {
int newCounter = counter;
for (newCounter = counter; newCounter <= counter + lookAheadWindow; newCounter++) {
String candidate = generateHOTP(key, newCounter);
if (candidate.equals(token)) {
return newCounter + 1;
}
}
return -1;
}
/**
* This method generates an OTP value for the given set of parameters.
*
* @param key the shared secret, HEX encoded
* @param counter a value that reflects a time
* @param returnDigits number of digits to return
* @param crypto the crypto function to use
* @return A numeric String in base 10 that includes return digits
* @throws java.security.GeneralSecurityException
*
*/
public String generateOTP(String key, String counter, int returnDigits, String crypto) {
String result = null;
byte[] hash;
// Using the counter
// First 8 bytes are for the movingFactor
// Complaint with base RFC 4226 (HOTP)
while (counter.length() < 16)
counter = "0" + counter;
// Get the HEX in a Byte[]
byte[] msg = hexStr2Bytes(counter);
// Adding one byte to get the right conversion
// byte[] k = hexStr2Bytes(key);
byte[] k = key.getBytes();
hash = hmac_sha1(crypto, k, msg);
// put selected bytes into result int
int offset = hash[hash.length - 1] & 0xf;
int binary = ((hash[offset] & 0x7f) << 24) | ((hash[offset + 1] & 0xff) << 16) | ((hash[offset + 2] & 0xff) << 8)
| (hash[offset + 3] & 0xff);
int otp = binary % DIGITS_POWER[returnDigits];
result = Integer.toString(otp);
while (result.length() < returnDigits) {
result = "0" + result;
}
return result;
}
/**
* This method uses the JCE to provide the crypto algorithm. HMAC computes a Hashed Message Authentication Code with the
* crypto hash algorithm as a parameter.
*
* @param crypto the crypto algorithm (HmacSHA1, HmacSHA256, HmacSHA512)
* @param keyBytes the bytes to use for the HMAC key
* @param text the message or text to be authenticated.
* @throws java.security.NoSuchAlgorithmException
*
* @throws java.security.InvalidKeyException
*
*/
private byte[] hmac_sha1(String crypto, byte[] keyBytes, byte[] text) {
byte[] value;
try {
Mac hmac = Mac.getInstance(crypto);
SecretKeySpec macKey = new SecretKeySpec(keyBytes, "RAW");
hmac.init(macKey);
value = hmac.doFinal(text);
} catch (Exception e) {
throw new RuntimeException(e);
}
return value;
}
/**
* This method converts HEX string to Byte[]
*
* @param hex the HEX string
* @return A byte array
*/
private byte[] hexStr2Bytes(String hex) {
// Adding one byte to get the right conversion
// values starting with "0" can be converted
byte[] bArray = new BigInteger("10" + hex, 16).toByteArray();
// Copy all the REAL bytes, not the "first"
byte[] ret = new byte[bArray.length - 1];
for (int i = 0; i < ret.length; i++)
ret[i] = bArray[i + 1];
return ret;
}
}
