23C3 - 1.5

23rd Chaos Communication Congress
Who can you trust?

Felix von Leitner
Day 2
Room Saal 2
Start time 14:00
Duration 01:00
ID 1658
Event type Lecture
Track Hacking
Language English

How to implement bignum arithmetic

A short look at my pet project implementation

Assembly language skills are a bonus, but not strictly required. This lecture will explain how software like OpenSSL and GnuPG do their arithmetic on 1024 bit numbers. This is not about how RSA works, or about how AES works. This is just about how to add and multiply big numbers. I will explain the algorithms, show some code, and give some timings.

Everyone knows that RSA keys are typically 1024 bits and up, but computers only operate on 32-bit or 64-bit quantities at a time. How does software like OpenSSL or GnuPG then do arithmetic on those long numbers?

This talk will show how it's done.