Peritaje médico en los delitos sexuales

person publicly distributes the key to encrypt messages sent to him, but keeps secret the asym- metric key that decrypts them. The values of the numbers chosen for the keys are so high as to make the encryption effectively unbreakable. The best-known form of public key cryptography is PGP (Pretty Good Privacy), a free computer program. According to one authority, even if every personal computer in the world were put to the task of trying to crack a single message encrypted with PGP, it would take approximately 12 times the age of the universe to succeed.

Computer Cryptography Rules

In game terms, you can resolve attempts to encrypt and decrypt messages protected by com- puterized cryptography using the two computers’ Cryptography rolls (with their operators’ rolls as Complementary, if appropriate) in a Skill Versus Skill Contest. (In some cases Computer Pro- gramming or SS: Mathematics may be Comple- mentary Skills.) But the truly important factor is the power and sophistication of the computer’s cryptography software.

The strength of computer encryption depends on the key length, or number of bits in the keys used to encipher and decipher a message — 16 bits, 32 bits, 64 bits, and so on. The number of bits equals a negative modifier to attempts to decrypt the message without a key. For example, trying to crack a message encrypted with 256 bit encryption entails a -256 penalty! The accompanying table provides suggested guidelines for the strength of a computer’s cryptographic software, based on its Cryptography roll.

Cryptographic software also provides a bonus for decrypting messages; the bonus equals half of its encryption penalty. For example, a computer with Cryptography 16- can encrypt messages so well that attempts to break them incur a -128 penalty; if it tries to decrypt a message without the key, it receives a +64 bonus. As a result, in most cases a character has no hope of breaking a cipher encoded by computers as powerful or more powerful than the ones he has access to, but some chance to break encryption created by weaker or less sophisticated computers.

The bonuses and penalties for computerized Cryptography apply only to ciphers created by computers. When used to crack a cipher gener- ated by hand, the computer uses its standard Cryptography roll. However, the GM may, in his discretion, allow characters to apply some or all of a computer’s Cryptography bonus to non-computer- ized codes — for example, perhaps they could enter a handwritten substitution cipher into a computer and use the computer’s power to break the code in just a few seconds by running through all possible substitutions. As always, common sense, dramatic sense, and considerations of game balance should be the deciding factors.

Of course, it’s entirely possible that someone will come up with a way to easily break computer- ized cryptography (this was the central plot device driving the movie Sneakers, for example). The codebreakers having caught up to the codemakers, the race will start again with further attempts to create inviolable codes... followed by attempts to decrypt them.

CIPHER MACHINE

CRYPTOGRAPHY

Cryptography Roll Strength Of Encryption

8- -1 penalty 9- to 11- -2 penalty 12- to 15- -4 penalty 16- to 20- -8 penalty 21- to 25- -16 penalty ...and so on

Steganography

Also falling within the purview of the Cryp-

tography Skill is steganography, the practice of

secretly communicating messages not by encoding them, but by hiding them. Anyone who finds the message can read it... but first he has to find it!

In ancient times, people used many clever but (by modern standards) low-tech methods to hide messages. Examples include:

■ scraping the wax off a tablet, writing a message

on the board, and pouring wax back on top so the object looks like an ordinary, blank tablet

■ shaving a slave’s head, writing the message on his

scalp, and then letting his hair regrow to hide the message

■ writing the message on silk, crumpling the silk

into a tiny ball, coating the ball with wax, having the messenger swallow the wax ball, then retrieving the wax ball from his feces

■ the use of invisible ink — inks that only show up

when treated in specific ways

As technology became more advanced, so did steganography. For example, during World War II and the Cold War, nations could use

microdots — a page of text shrunk down to the

size of a period on a printed page — to convey information. Modern cryptographers use com- puterized steganography to hide all sorts of data in seemingly innocent graphics.

Of course, it’s possible to use both encryp- tion and steganography on a single message. That provides two levels of secrecy to protect the message.

Translation

In some campaigns, Cryptography can also represent a character’s knowledge of ancient, obscure, and dead languages. While the character cannot speak these languages, or read them easily, he can, given sufficient time and reference materi- als, translate them — thus providing a way to read the grimoires of long-dead wizards, the instruc- tions on treasure maps from empires that fell mil- lennia ago, and so forth. If a character can only use Cryptography this way (i.e., he cannot decode and encode messages), he can buy it with a -½ Limita- tion, Translation Only.

Other Rules

EQUIPMENT

As discussed in detail above, for thousands of years Cryptography generally involved no technology beyond that necessary to write. But once cipher machines are developed, technol- ogy rapidly comes to play a more and more important part in cryptology. By the time of the Enigma machine and, later, computers, reliable Cryptography virtually requires equip- ment; without it, a character lacks the means to securely encrypt messages or the means to decrypt enemy messages.

POWERS AND CRYPTOGRAPHY

Characters may be able to use some Powers to overcome the need for Cryptography. For example, Retrocognition or the ability to read the “psychic traces” left in the message by the encoder (Detect True Meaning Of Message, or the like) might render the most complex, secure code transparent to the character. For this reason, the GM may want to forbid or restrict the use of such powers; they’re likely to spoil the mystery and fun of deciphering a message “the old-fashioned way.”

Similarly, some Powers may help charac- ters encode messages. An Uncontrolled, 0 END form of Images could be applied to a message to “encode” it, for example — and possibly even be “programmed” to change appearance every few minutes so that a cryptanalyst can’t possibly have the time to decode it.

CONSEQUENCES OF FAILURE

When a character encrypts a message, fail- ure usually means improper coding, leading to a garbled message. A badly-failed roll (by 4 or more) may even communicate the wrong message.

When a character tries to decode a message (or find a steganographically hidden message), fail- ure typically means the character can’t break the code. A badly-failed roll (by 4 or more) may mean he thinks he’s broken it, but in fact he’s mistaken and has incorrectly “translated” it.

COMPUTERIZED CRYPTOGRAPHY

Cryptography Roll Bits Of Encryption Bonus To Decrypt

8- 8 (-8 penalty to decrypt) +4 9- to 11- 16 (-16 penalty to decrypt) +8 12-, 13- 32 (-32 penalty to decrypt) +16 14-, 15- 64 (-64 penalty to decrypt) +32 16-, 17- 128 (-128 penalty to decrypt) +64 18- to 20- 256 (-256 penalty to decrypt) +128 21- to 25- 512 (-512 penalty to decrypt) +256 26- to 30- 1,024 (-1,024 penalty to decrypt) +512 31- to 35- 2,048 (-2,048 penalty to decrypt) +1,024 ...and so on

BASE TIMES

Except in the cases of the simplest handwrit- ten ciphers and the most advanced decryption tech- nology, encoding or decoding a message is usually a time-consuming and laborious process. Several factors influence the time involved.

The first is the length of the message — the longer it is, the longer it takes to encode. On the other hand, as noted in the Cryptography Modi- fiers table, the longer the message the greater the chances of cryptanalyzing it successfully.

The second is the complexity of the code. A simple substitution cipher can sometimes be writ- ten nearly as quickly as normal writing; creating and writing a message in a VigenPre cipher could take days. Superencipherment, steganography, and the like only increase the time.

The Cryptography Base Times table provides suggested guidelines for the time needed to encode and decode messages. The GM should alter these as he sees fit.

SUBDIVIDING CRYPTOGRAPHY

In campaigns involving a lot of cryptology work, the GM might want to change Cryptography into three Intellect Skills: Encryption (the ability to create codes and write messages in code); Decryp- tion (codebreaking); and Steganography. This divi- sion isn’t entirely logical, but does allow characters to specialize in one aspect of Cryptography easily.

CRYPTOGRAPHY BY GENRE Cyberpunk/Near Future

It’s possible that by the Cyberpunk era, man- kind will have invented quantum computers or other such super-fast computing devices. These are computers so fast that they can run through the calculations needed to crack computerized encryption swiftly enough to render such encryp- tion worthless. But of course, forms of encryption are likely to advance as well, creating practical quantum cryptography. Therefore, you’re probably safe in adapting the rules outlined above for com- puterized cryptography and using them with a few changes in terminology and the like.

As noted above, cryptography tends to be very technology-sensitive. You may want to apply the “technology levels” modifier discussed on page 39 in addition to the modifiers in the Computer Cryp- tography Table — though those modifiers are, in effect, just a specific elaboration of the general rules for varying types of technology.

Dark Champions

Computerized cryptography is firmly entrenched by the standard Dark Champions time period (late twentieth/early twenty-first centuries). In fact, the ease with which essen- tially unbreakable cryptography is available to the public significantly hinders the ability of law enforcement — and vigilantes — to read infor- mation intercepted from criminals and terrorists via wiretapping and the like.

Fantasy

In the Fantasy era, most ciphers fall into the Very Simple, Simple, or Average categories... but then again, so does the knowledge of how to decrypt them. Simple steganography is also popu- lar. But in a Fantasy setting, characters may have to contend with magical cryptography. Boadlane’s Lens Of Enlightenment and Boadlane’s Spell Of The Secret Script (The Fantasy Hero Grimoire, pages 220-21) are two examples of spells that could per- form a cryptographic function, but many others are possible. Instead of pitting the encoders’ ingenuity computers against the cryptanalyst’s ingenuity and computers, cryptology in a Fantasy setting may be a matter of magical power and insight.

If an otherwise mundane code or cipher involves magic (such as coded writing that periodi- cally changes form), a character suffers a stiff pen- alty to decode it (at least -3, and often more; decod- ing the text may be impossible without the magical command word).

The Translation Only form of Cryptogra- phy also crops up as a way for characters to read ancient, obscure, or dead languages. A wizard may buy it so he can read old grimoires and scrolls, while a tombrobber may learn it so he can decipher inscriptions on crypts and directions on ancient treasure maps. Occult texts are often written in actual code as well. (Occultists actually wrote some of the first studies of cryptography.) Kabbalists can use Cryptography as a Complementary Skill to find hidden numerological meanings in sacred texts.

Martial Arts

The use of Cryptography in a Ninja Hero cam- paign depends primarily on the time period the campaign’s set in — a modern-day campaign would be like Dark Champions, while one set in ancient China would take after Fantasy Hero.