DISCLAIMER: I don't know a lot about cryptography.
I was reading about the Hashlet, and I had a couple questions. The Hashlet is described as:
SHA256 hardware device with a hardware RNG, and protected key storage on an easy to mount board for the BeagleBone Black or Raspberry Pi.
The Hashlet provides an easy way to add secure authentication to your BeagleBone Black or Pi. It has hardware protected key storage and performs the SHA-256 algorithm in the chip. Using a shared secret key, it adds authentication and message integrity to your embedded project.
This means that another server, application, or a remote device can validate that a message originated from your Hashlet.
Correct me if I'm wrong, but this means that the Hashlet does NOT encrypt messages. It only hashes the message and attaches a signature at the end that contains the output of the SHA function.
This may be totally wrong, but I got stuck here. How is the message verified? What does the server have to do with the private key to know that the message is authentic? Does it re-hash the text?
Any help is appreciated- I'd love to expand my knowledge of cryptography to figure out how this works.