Hashcat boasts its ability to crack over 200+ hashing algorithms, but there isn't much documentation on much of them. `Hashcat --help` shows it has support for HMAC cracking, but it's not very straightforward with the syntax (it just says "1450 | HMAC-SHA256 (key = $pass)" ). I understand that HMAC-SHA256 takes two parameters, one being the key and one being the message, but I'm not sure how to specify both of these with Hashcat. 

What is the proper syntax for Hashcat to crack HMAC-sha256? I have two files, one contains the message and one contains the hash. I know the password and I can verify the HMAC hash using `openssl dgst -SHA256 -hmac "mypassphrase" message.txt`