Verified answer

A good place to start;

http://www.amazon.com/exec/obidos/isbn=0879519193/...

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Don't skip your math classes

Depends on what kind of "codes" you are trying to break.

Passwords are easier to bypass/reset (google Sarah Palin e-Mail) or social engineer than to crack. However, any brute force routine will do it.

For hash-based codes, you have to run analytic programs that try all kinds of formulas until they find the answer. There are specialized hardware setups for doing this, as well as distributed programs that run on hundreds or thousands of computers to figure it out.

what kind of "codes" are you trying to break?

Very carefully.

What type of code are you trying to break? Can you provide more details?