CS338 Computer Security
Friday, 29 September 2023

+ Today
- Asymmetric cryptography pragmatics: what's in those key files?

+ Problems
- How to represent keys (and related things) in a
    bit-for-bit reliable way (and why?)
- Storing integers of arbitrary length

+ File format ambiguities
- CSV files
- indenting in python
- ...

+ Strategy
- Describe the structure formally (ASN.1)
- Encode an instance as an unambiguous byte sequence (DER)
- Result is non-ASCII; package it as ASCII for ease of
  visual examination and safety of transfer (PEM)
    - descriptive header
    - base64 contents
    - descriptive footer

+ Organizations, etc.
- RSA (for-profit company; developer of the PKCS document series)
- IETF (RFC publisher)
- OpenBSD Project (developer of OpenSSH)