How to generate HMAC-SHA1 Signature in android?

Question

This is my base String:

        String args =\"oauth_consumer_key=\"+enc(consumerkey) +
                   \"&oauth_nonce=\"+enc(generateNonce()) +
              


        

Answer 1

Femi's answer is absolutely correct, however, it wasn't obvious for me what exactly is intval(b). As i understood it's b & 0xFF.

Also I applied some optimizations (that I found here) and here is my code:

private static String hmacSha1(String value, String key)
        throws UnsupportedEncodingException, NoSuchAlgorithmException,
        InvalidKeyException {
    String type = "HmacSHA1";
    SecretKeySpec secret = new SecretKeySpec(key.getBytes(), type);
    Mac mac = Mac.getInstance(type);
    mac.init(secret);
    byte[] bytes = mac.doFinal(value.getBytes());
    return bytesToHex(bytes);
}

private final static char[] hexArray = "0123456789abcdef".toCharArray();

private static String bytesToHex(byte[] bytes) {
    char[] hexChars = new char[bytes.length * 2];
    int v;
    for (int j = 0; 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);
}