Ruby and PHP HMACs not agreeing

Question

I\'m trying to create an HMAC in Ruby and then verify it in PHP.

Ruby:

require \'openssl\'
message = \"A522EBF2-5083-484D-99D9-AA97CE49FC6C,1234567890,/a         


        

Answer 1

I noticed that

hash = HMAC::SHA256(key) 
hash << a
hash << b
hash << c

gives different result than PHP's

hash_hmac('sha256',$a.$b.$c, $key)

beware of this caveat. To get correct, just do

hash = HMAC::SHA256(key)
hash << "#{a}#{b}#{c}"