What is an LFSR? An LFSR is a Linear Feedback Shift Register. It’s a simple way of generating a sequence of numbers that look random. Used in cryptography and in generating pseudo-random numbers, they are interesting because they are so simple. Shift bits and feed a few of them back into the sequence. That’s it. Important note: LFSRs are not cryptographically secure on their own. ESPECIALLY 8-bit LFSRs. More on that in the next post on this topic.

I was recently on a video call with a friend, throwing around some ideas for a new product. I mentioned adding large signed numbers in assembly and using two’s complement. He asked me what two’s complement was. I was a little surprised that he didn’t know. He’s been a Java programmer for more than 30 years. Java and Python programmers (and others like gasp Commodore / MicroSoft BASIC) don’t have a native unsigned integer type.