MD5, among others, is not designed to encrypt and later decrypt. It is one-way-only.

The idea is (for example) to encrypt a password. Instead of decrypting the password, the user's input is encrypted with the same algorithm. If it matches the previously saved encrypted password, then the user's input is assumed to be correct - although there is a remote chance of two different passwords producing the same hashcode (MD5 or whatever).

Perhaps you can use it this way; otherwise, you will have to continue searching for other encryption/decription algorithms.

>I am not sure if anyone here can help me, but I am getting migraines from attempting to create an encryption method that suits my needs. I tried looking at VB.Net's built in TripleDES, MD5, etc...My problem is that those methods encrypt string into unreadable text. I tried converting the encrypted text to Hex, but that instantly doubles the string size, which is unacceptable.
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>I am trying to create an encryption method that ends up returning only Digits and Alpha Characters, which then I can use for "Application Licensing." Inside the "License" I am looking to embed certain information, but the license needs to be in readable/typable format for the enduser to key in. I also need it to be a 1:1 ratio, in other words the string outputed by the encryption method is the same size as the string inputted. I tried creating my own Transposition Matrix and Encryption method using it which I was able to get working, but "decrypting" ended up being a disaster. It's easier to scamble information then it is to unscramble it. :-)
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>Can anyone help me? Either directing me to some samples if possible, or maybe I can post the code that I have and maybe get some help on how to fix it?