Java Sample Code for Calculating HMAC-SHA1 Signatures

gistfile1.java

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SignatureException;
import java.util.Formatter;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;


/**
 * The <tt>HmacSha1Signature</tt> shows how to calculate 
 * a message authentication code using HMAC-SHA1 algorithm.
 *
 * <pre>
 * % java -version
 * java version "1.6.0_11"
 * % javac HmacSha1Signature.java 
 * % java -ea HmacSha1Signature
 * 104152c5bfdca07bc633eebd46199f0255c9f49d
 * </pre>
 *
 */
public class HmacSha1Signature {
	private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

	private static String toHexString(byte[] bytes) {
		Formatter formatter = new Formatter();
		
		for (byte b : bytes) {
			formatter.format("%02x", b);
		}

		return formatter.toString();
	}

	public static String calculateRFC2104HMAC(String data, String key)
		throws SignatureException, NoSuchAlgorithmException, InvalidKeyException
	{
		SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(), HMAC_SHA1_ALGORITHM);
		Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
		mac.init(signingKey);
		return toHexString(mac.doFinal(data.getBytes()));
	}

	public static void main(String[] args) throws Exception {
		String hmac = calculateRFC2104HMAC("data", "key");

		System.out.println(hmac);
		assert hmac.equals("104152c5bfdca07bc633eebd46199f0255c9f49d");
	}
}

thanks!

Great!

thanks man!

Thanks!

👍

nice, thanks

thanks!

Great job man !

Thanks!

Thanks!

Here's the same thing in Kotlin for your convenience:

import java.security.InvalidKeyException
import java.security.NoSuchAlgorithmException
import java.security.SignatureException
import java.util.*
import javax.crypto.Mac
import javax.crypto.spec.SecretKeySpec

object HmacSha1Signature {
  private val HMAC_SHA1_ALGORITHM = "HmacSHA1"

  private fun toHexString(bytes: ByteArray): String {
    val formatter = Formatter()

    for (b in bytes) {
      formatter.format("%02x", b)
    }

    return formatter.toString()
  }

  @Throws(SignatureException::class, NoSuchAlgorithmException::class, InvalidKeyException::class)
  fun calculateRFC2104HMAC(data: String, key: String): String {
    val signingKey = SecretKeySpec(key.toByteArray(), HMAC_SHA1_ALGORITHM)
    val mac = Mac.getInstance(HMAC_SHA1_ALGORITHM)
    mac.init(signingKey)
    return toHexString(mac.doFinal(data.toByteArray()))
  }
}

Thanks! @ishikawa and @JohannesRudolph.

Just FYI, there's a common cryptography bug in the above code. A lot of your key bytes are guessable because you're using UTF8 encoding. That means no non-printable bytes will ever appear in your key and your key entropy is greatly reduced. Always always randomly generate your keys using a SecureRandom and Base64 encode them. Otherwise, only bytes that are printable will be used as key bytes and number of guesses a brute force attacker would have to do is GREATLY reduced!

The correct way to generate a key is:

	public static String generateRandomKey() throws NoSuchAlgorithmException {
		SecureRandom secureRandom = new SecureRandom(SecureRandom.getSeed(32));
		KeyGenerator keyGen = KeyGenerator.getInstance("HmacSHA1");
		keyGen.init(secureRandom);
		SecretKey secretKey = keyGen.generateKey();
		String encodedKey = Base64.getEncoder().encodeToString(secretKey.getEncoded());
		return encodedKey;
	}

As an example, the above code can produce 0x6 as a key byte, or 00000110. This binary value cannot be encoded as UTF-8: http://bit.ly/2nOaqFw

import java.security.SignatureException;
import java.util.Base64;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class HMAC_SHA1 {
	public static String Signature(String xData, String AppKey) throws java.security.SignatureException {
		try {
			final Base64.Encoder encoder = Base64.getEncoder();
			// get an hmac_sha1 key from the raw key bytes
			SecretKeySpec signingKey = new SecretKeySpec(AppKey.getBytes("UTF-8"),"HmacSHA1");

			// get an hmac_sha1 Mac instance and initialize with the signing key
			Mac mac = Mac.getInstance("HmacSHA1");
			mac.init(signingKey);

			// compute the hmac on input data bytes
			byte[] rawHmac = mac.doFinal(xData.getBytes("UTF-8"));
			String result = encoder.encodeToString(rawHmac);
			return result;

		} catch (Exception e) {
			throw new SignatureException("Failed to generate HMAC : "+ e.getMessage());
		}
	}
}

Thank You!

thanks

nice.

{
final Base64.Encoder encoder = Base64.getEncoder();
SecretKeySpec signingKey;
try {
signingKey = new SecretKeySpec(encoder.encode(key.getBytes("UTF-8")), ""HmacSHA1"");
Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
mac.init(signingKey);
return toHexString(mac.doFinal(encoder.encode(data.getBytes("UTF-8"))));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}

import java.security.SignatureException;
import java.util.Base64;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class HMAC_SHA1 {
	public static String Signature(String xData, String AppKey) throws java.security.SignatureException {
		try {
			final Base64.Encoder encoder = Base64.getEncoder();
			// get an hmac_sha1 key from the raw key bytes
			SecretKeySpec signingKey = new SecretKeySpec(AppKey.getBytes("UTF-8"),"HmacSHA1");

			// get an hmac_sha1 Mac instance and initialize with the signing key
			Mac mac = Mac.getInstance("HmacSHA1");
			mac.init(signingKey);

			// compute the hmac on input data bytes
			byte[] rawHmac = mac.doFinal(xData.getBytes("UTF-8"));
			String result = encoder.encodeToString(rawHmac);
			return result;

		} catch (Exception e) {
			throw new SignatureException("Failed to generate HMAC : "+ e.getMessage());
		}
	}
}

what is xData

for Scala (taken answer above):

  import javax.crypto.Mac
  import javax.crypto.spec.SecretKeySpec
  import org.apache.commons.codec.binary.Base64

  def encryptHMACSHA1(value: String, secretKey: String): String = {
    val signingKey = new SecretKeySpec(secretKey.getBytes, "HmacSHA1")
    val mac = Mac.getInstance("HmacSHA1")
    mac.init(signingKey)
    val rawHmac = mac.doFinal(value.getBytes)
    Base64.encodeBase64String(rawHmac)
  }

Perfect for my needs, thanks so much!

Thanks :)

Thanks!

Thanks