I wasn't sure which section I should ask this question in, because it isn't a true security question, but it is a question about using the SHA1 algorithm, so I figured that I'd have the best luck in the security section.
I'm using SHA1 as a hash function in my application, I was wondering if anybody knew what factors to use (or not to use) when giving data to the function to compute the hash for avoiding collisions. For example is there a range of optimal input lengths that reduce collisions? Is it bad to use a limited range of input values (ie. only ascii chars). If anybody has any insight on this it would be very useful.