HMAC for newbies
Apr 25, 2024
TL;DR version of using HMAC for checking message integrity
> Sender
$ echo "super secret message" > data.txt
$ openssl dgst -sha256 -hmac "secret_key" data.txt
HMAC-SHA2-256(data.txt)= 5544937d3a88981fa2af83c3d117b009b825284876087940c8cad1fc7ee70450> Receiver
$ export hmac="5544937d3a88981fa2af83c3d117b009b825284876087940c8cad1fc7ee70450"
$ openssl dgst -sha256 -hmac "secret_key" data.txt | grep $hmac && echo "HMAC Verified" || echo "HMAC Verification Failed"
HMAC-SHA2-256(data.txt)= 5544937d3a88981fa2af83c3d117b009b825284876087940c8cad1fc7ee70450
HMAC Verified