If I wanted to write a program that generated all possible passwords using alphanumeric characters and wrote the output to a file, what language would would be best suited for writing something like that, for the purpose of penetration testing?
Edit: I already know C, C++, Java, javascript, python, ruby, HTML, CSS, and objective-c. I just have trouble identifying what language is better for solving which problems.
Without sounding pedantic, here are a few things to consider :
What's this "efficiency" thing you're talking about? How do you measure it?
Are you sure it is connected to the language you write the program in?
Third, you realize that there are a very, very large range of possible passwords for most alphabets and lengths above, say, 6 or 7 chars? Are you sure this is the solution you need?
Fourth, aren't any solutions out there which already solve your problem?
More to the point: instead of choosing a language suited to the problem domain, consider choosing one which you are more experienced. But do check if your approach is the correct one.
If you don't want to generate random passwords, but kind of a rainbow table without the need of hashes, you might just want to generate and 'increment' char sequences of certain lengths during the brute force test, like aaaa, aaab, aaac, ... You'd use the language, in which that test is written.
This can be written any number of ways. If I recall correctly, Python had a relatively simple structure for loops and writing to a file. Although, so does C....
So pick a language you want to learn, and dive in.