>I currently have the need to acces a database where some password are encrypted with Chiper50. I don't can use Fox here. I need to know what algorithm is in use in Chiper50 and how traslate it to .NET. I take a look System.Security.Cryptography and I don't know what class match Chiper50 functionality...

The C source code is available at Cipher50 - Source Code File #21474. I guess you can build something for .Net based on it.