Is there any function for creating Hmac256 string in android?

Question

Is there any function for creating Hmac256 string in android ? I am using php as my back end for my android application, in php we can create hmac256 string using the php function hash_hmac () [ ref ] is there any function like this in Android

Please help me.

Solution 1

Calculate the message digest with the hashing algorithm HMAC-SHA256 in the Android platform:

private void generateHashWithHmac256(String message, String key) {
    try {
        final String hashingAlgorithm = "HmacSHA256"; //or "HmacSHA1", "HmacSHA512"

        byte[] bytes = hmac(hashingAlgorithm, key.getBytes(), message.getBytes());

        final String messageDigest = bytesToHex(bytes);

        Log.i(TAG, "message digest: " + messageDigest);

    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static byte[] hmac(String algorithm, byte[] key, byte[] message) throws NoSuchAlgorithmException, InvalidKeyException {
    Mac mac = Mac.getInstance(algorithm);
    mac.init(new SecretKeySpec(key, algorithm));
    return mac.doFinal(message);
}

public static String bytesToHex(byte[] bytes) {
    final char[] hexArray = "0123456789abcdef".toCharArray();
    char[] hexChars = new char[bytes.length * 2];
    for (int j = 0, v; j < bytes.length; j++) {
        v = bytes[j] & 0xFF;
        hexChars[j * 2] = hexArray[v >>> 4];
        hexChars[j * 2 + 1] = hexArray[v & 0x0F];
    }
    return new String(hexChars);
}

This approach does not require any external dependency.

Solution 2

Try below code

public static String encode(String key, String data) throws Exception {
    Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
    SecretKeySpec secret_key = new SecretKeySpec(key.getBytes("UTF-8"), "HmacSHA256");
    sha256_HMAC.init(secret_key);

    return Hex.encodeHexString(sha256_HMAC.doFinal(data.getBytes("UTF-8")));
}

Hex.encodeHexString() to use this method, add below dependency to your app gradle.

compile 'org.apache.directory.studio:org.apache.commons.codec:1.8'

This will convert resulted string to hex string same as your php hash_hmac() funtion generates.

Comments

[Michael]

Have you tried using the Mac class with "Hmac256" as the algorithm name?

[Michael]

I'm sure you can find plenty of examples of how to use that class if you search around.

[f.trajkovski]

I am getting this using your method: error: cannot find symbol return Hex.encodeHexString(sha256_HMAC.doFinal(data.getBytes("UTF-8‌​")));

[Jesse Buss]

Make sure you're importing the correct Hex object. Should be org.apache.commons.codec.binary.Hex (as specified in the dependency above) not com.google.android.gms.common.util.Hex

[Kannan_SJD]

What does this mean final char[] hexArray = "0123456789abcdef".toCharArray();

[Ryan Amaral]

Is an array of char that is initialised with the hexadecimal numeral system. The word 'hexadecimal' means sixteen because this type of digital numbering system uses 16 different digits from 0-to-9, and A-to-F.