Cryptography
Name
Cryptography
Skill Attribute & Difficulty
Int - Hard
Defaults
Mathematics (Cryptology)-5
Prerequisites
None
Description
This is the ability to create and defeat encryption systems, codes, and ciphers. It is of use in wartime, espionage, and even business dealings. It covers all the techniques of your TL, which can range from unsophisticated substitution ciphers to state-of-the-art tactical encryption schemes.
Knowledge of a specific system, code, or cipher depends on your Security Clearance and allegiances (national, administrative, or both). In many settings, some level of Security Clearance is a prerequisite to learning this skill at all.
Treat an attempt to break an unknown code as a Contest of the Cryptography skill between the code-breaker and code-maker. The code-breaker must win to break the code. Repeated attempts are possible, but each attempt takes a day. The code-maker rolls only once, when they first create the code.
Specializations
Those with Cryptography skill may take an optional specialty in making or breaking codes. (The code-breaking specialty is often called “cryptanalysis.”)
Cryptography normally has no Int default, with two exceptions. Anyone can devise a trivial code or cipher by making an [5+Int] roll. This won’t stall a professional for long, of course. Likewise, anyone can make an [5+Int] roll to attempt to break such a trivial code (but not a code devised by someone with Cryptography skill).
Modifiers
Mathematical Ability. A computer with appropriate software gives a bonus (provided you know Computer Operation skill): +1 for a home computer, +2 for a mini-computer, +3 or +4 for a mainframe, and +5 or more for a supercomputer.
The code-breaker is at +5 if they have a sample of the code with translation,
and -5 if the message to be decoded is shorter than 25 words.
