How could I implement a digital signature in an application?

Question

I'm developing a software in Ruby on Rails that saves information about documents that requires fisical signatures. The idea is do it all digital including the signature. How could I do that? Do I have to save a hash in the database?

EDIT: Well, I mean Digital Signature

Answer 1

All depends on where you are and who your customers are. I'd recommend this wikipedia page as a jumping off point. Once you get the legal aspects figured out we can help you out more with the implementation details.

PS. I'm assuming you're not talking about cryptographic Digital Signatures. Let me know if I'm wrong.

Answer 2

I believe you are in fact referring to hash functions, or message digest functions. Take a look at Digest library... And yes, you'll probably have to remember returned hash to the DB.