IDA is a professional tool for program analysis. We illustrate it using the demo and freeware versions. (Install the Linux demo version in order to be able to debug the binary. Install the freeware version in order to be able to save and load database files.)
Watch the video by integeruser reversing the first stages of the starcrack binary. Try to complete the job and get a valid license number!
The following video shows the first part of starcrack using IDA for static analysis and gdb for dynamic analysis:
Here is IDA database from Lorenzo.