Calculate HMAC-SHA1 value of payload

hmac-sha1

/**
	 * @param key - client secret key
	 * @param data - can be any data (eg: http request or response payload)
	 * @return
	 */
public static String calculateHmacSHA1(String key, byte[] data) {

		if (key == null || data == null || data.length <= 0)
			return null;
		String HMAC_SHA1_ALGORITHM = "HmacSHA1";

		try {
			Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
			mac.init(new SecretKeySpec(key.getBytes(), HMAC_SHA1_ALGORITHM));

			byte[] rawHmac = mac.doFinal(data);
			return Base64.encodeBase64String(rawHmac);
		} catch (Exception e) {
		  // hanlde in your own way
			return null;
		}
	}