When writing an average new app in 2009, what's the most reasonable digest function to use, in terms of security and performance? (And how can I determine this in the future, as conditions change?)...

What is the difference between HTTP Digest Authentication and SSL from a performance, security and flexibility point of view?

I am trying to build a working encrypted signature for the Amazon S3 web service, writing a connection library using Objective C. I have run into HMAC SHA-1 digest problems with the ObjC code, so...

My problem: I'm looking for a way to represent a person's name and address as an encoded id. The id should contain only alpha-numeric characters, be collision-proof, and be represented in a smalle...