Cryptography

This is the ability to create and
defeat encryption systems, codes, and
ciphers. It is of use in wartime, espi-
onage, and even business dealings. It
covers all the techniques of your TL,
which can range from unsophisticat-
ed substitution ciphers to state-of-the-
art tactical encryption schemes.
Knowledge of a specific system, code,
or cipher depends on your Security
Clearance (p. 82) 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 Quick Contest of
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 he first
creates the code.
Those with Cryptography skill may
take an optional specialty (p. 169) in
making or breaking codes. (The code-
breaking specialty is often called
“cryptanalysis.”)
Cryptography normally has no IQ
default, with two exceptions. Anyone
can devise a trivial code or cipher by
making an IQ-5 roll. This won’t stall a
professional for long, of course.
Likewise, anyone can make an IQ-5
roll to attempt to break such a trivial
code (but not a code devised by some-
one with Cryptography skill), using
the Quick Contest system described
above.
Modifiers: Mathematical Ability
(p. 90). 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 he has a
sample of the code with translation,
and -5 if the message to be decoded is
shorter than 25 words. The code-
maker receives a bonus for the time
taken to create the code: consult the
Size and Speed/Range Table (p. 550),
look up the time in days in the
Range/Speed column (substituting
“days” for “yards”), and use the corre-
sponding bonus.