How to decrypt a string encrypted with HMACSHA1?

Question

I\'m an encryption novice trying to pass some values back and forth between systems. I can encrypt the value, but can\'t seem to figure out how to decrypt on the other end. I\

Answer 1

A simple one-way hash explaination as to why people would want to do it.

Lets say you have a user account with the username John and password Doe. You store the hash of the following string.

First name, your favorite number, and their selected password

for example: hash= myHash("john7@password")

             now hash = "qk239qa*@$)(*84509053903" or whatever

Now that hash is secure and cant be reversed back to figure out what your favorite number is in most cases. To check if the hash is the right one for logging in, you'd re-hash the supplied input (name,your number or w/e, password) and if you get the same exact hash, its a valid deal. wo0t isnt it completely simple!

--should I use the same key to re-hash my data?