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HMAC_SHA512 using java API

i am changing to code to integrate HMAC_SHA512 using java API


But i get Error code 99 Transaction cannot be accepted after the new change


I am using the TEST


As mentioned i am sending the  inputstring '^' delimeter

^API LOGIN ID^TransactionID^AMT^


Please let me know what is dong wrong  and any more inforemation you want from me


I do send the Hexa value Hex.encodeHex() API to get the Hexvalue

I’m not understanding. The hash value is submitted in your request as an http post under that name, correct? You are saying that you submit x_fp_hash in your post and the API compares it to md5?

Originally the value in x_fp_hash(fingerprint generated was using MD5 hash, that used transaction key)

Now i am following the guide to to upgrade  to HmacSHA512 that says to use the SecurityKey .

I created a new SecurityKey.

I am creating the new value for finger print using securitykey and HmacSHA512 hashing 

This value is set in the x_fp_hash hidden field of paymentform and submitted


The moment i submit i receive erro code 99. That means my fingerprint does not match with that of merchant. However if i revert the code old way it launches payment form.


the java code 

key is security key and data is APILOGINID^TransactiodID^timestampe^amt^


Mac sha512_HMAC = Mac.getInstance("HmacSHA512");
SecretKeySpec secret_key = new SecretKeySpec(key.getBytes("UTF-8"), "HmacSHA512");

return Hex.encodeHexString(sha512_HMAC.doFinal(data.getBytes("UTF-8")));


Please help let me know what am i doing wrong?

FYI The old way is SIM implementation.

I got it working with new HASH the issue was conversion of the long key to byte array.

Method to convert the SecurityKey

public static byte[] hex2bin(String hex) throws NumberFormatException {
if (hex.length() % 2 > 0) {
throw new NumberFormatException("Hexadecimal input string must have an even length.");
byte[] r = new byte[hex.length() / 2];
for (int i = hex.length(); i > 0;) {
r[i / 2 - 1] = (byte) (digit(hex.charAt(--i)) | (digit(hex.charAt(--i)) << 4));
return r;

public String encode(byte[] key, String data) {
try {
//String hexaString = Hex.encodeHexString(key.getBytes()) ;
Mac sha512_HMAC = Mac.getInstance("HmacSHA512");
SecretKeySpec secret_key = new SecretKeySpec(key,"HmacSHA512");

return Hex.encodeHexString(sha512_HMAC.doFinal(data.getBytes("UTF-8")));

// return new String(Hex.encodeHex(sha512_HMAC.doFinal(data.getBytes("UTF-8"))));

} catch (NoSuchAlgorithmException e) {
} catch (InvalidKeyException e) {
} catch (UnsupportedEncodingException e) {

return null;

Thanks for the help




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