CSCI 107 — Bits

Reading from Blown to Bits for next class


To appreciate encryption, we must learn a bit about bits. We’ll start with Semmy’s Digital Encodings lecture notes.

Bit strings

What is the number of bitstrings of length n.

n2nthings to consider
1665536Common for “personal” computer in the 80’s
324294967296 Common for today’s computers
Could cause problems in the year 2038
56 72057594037927936 Number of DES keys
64 18446744073709551616 Number of Lucifer keys
256 ~ 1.15 × 1077 Common for AES keys
Number of observable atoms about 4 × 1080
2048 ~ 3.2 × 10626 Common for RSA keys
4096 ~ 1 × 101253 Hard RSA keys

Is it possible that Edward Snowden really doesn’t know how to decrypt all documents he has?

Chalkboard exercise

Representing information

Getting ready

Following instructions given in lab, do the following.

And if time remains