Reg: HMAC Calculation

Hi All,

How are you?

I am facing the following issue with Qc3CalculateHMAC API.

Currently i am trying to do the JWT token validation in iSeries, to do that
i am planning to generate the HMAC using the header, payload and signed
secret key.

The logic i am using is Passing the input data as
Header(Base64encoded).Payload(Base64encoded).

1) For Base64 decoding - SYSTOOLS.BASE64ENCODE function is used.
2) Algorithm - SHA256.
3) I am passing the Secret Key as plain character text using "KEYD0200"

But the HMAC generated by the API is not correct. Am i doing anything wrong?

Qc3CalculateHMAC(
%addr(headerPayload) :
%len(%trimr(headerPayload)) :
'DATA0100' :
algd0500 :
'ALGD0500' :
keyparam :
'KEYD0200' :
'0' : // crypto
*blank : // crypto dev
hash :
QUSEC);

Could anyone please help me to figure out the issue?

Regards,
Suren K