The Hindu Business Line : Some secrets are to be said in bits

YOU can't think of a VIP without a black cat; nor data transmission without a mention of encryption. Practical Cryptography by Bruce Schneier is about how to secure one's digital future. "Without a secure computer system, you don't make money, you don't expand, and bottom-line - you don't survive," states the back cover. The book discusses practical rules for choosing and using cryptographic primitives, from block ciphers to digital signatures; implementing cryptographic algorithms and systems in a secure way on today's computers; and so on. A few crypts:

Security does not come for free. If you want security, you'll have to pay the price. If you can't afford it, then you won't get good security. It is as simple as that.

Of all the cryptographic primitives, hash functions are the most versatile. You can use a hash function for encryption, authentication, and even for a simple digital signature scheme. A hash function takes as input an arbitrarily long string of bits (or bytes) and produces a fixed-size result. Hash functions are sometimes called message digest functions, and the hash result is also known as the digest, or the fingerprint.

Something that surprises many people is that simply overwriting data in memory does not delete the data. The details depend to some extent on the exact type of memory involved, but basically if you store data in a memory location, that location slowly starts to `learn' the data. For instance, if the same data is stored for a time in the same location in static RAM (SRAM), then this data becomes the preferred power-up state of that memory.

Don't trust any of the random number generators provided with your programming language or your operating system. Most of them fail virtually all requirements for a cryptographically strong PRNG (pseudorandom number generator).

Many companies file patents not so much to enforce them, but to defend themselves. If you have a whole pile of patents, and your competitor sues you over one of his patents, you can always find one of your patents that he infringed, or at least one that you can allege that he infringed. It is a bit like MAD: mutually assured destruction. If you sue me, I'll sue you, and we both lose enormous amounts of money (on legal fees and lost opportunities). Sometimes we see two companies involved in this game of chicken. Quite often they settle after a year or so, once cooler heads realise that a mutual suicide pact doesn't provide much shareholder value.

A book on how to make a secret of what you want to say, even if it is not something critical.

Communication class

EVERYBODY talks about digital communication systems, data transfer, networks, mobile computing and so on, and you are looking for a primer about these. Try out Dr K.V.K.K. Prasad's Principles of Digital Communication Systems and Computer Networks. The book discusses information theory, PSTN, RS232, optical communication, signalling system, ISDN, frame relay, ATM, WAP, 3G, Bluetooth, IrDA, radio paging, information security and a host of other topics. A sampler:

Twisted pair gets its name as a pair of copper wires is twisted to form the transmission medium. This is the least expensive transmission medium and hence the most widely used one - in underground telephone network, PBX and LAN. Coaxial cable is used extensively for cable TV distribution, long-distance telephone trunks and so on. Optic fibre is now the most preferred because of the high rates that can be supported and low attenuation (that is, signal loss).

The three widely used frequency bands in satellite communication systems are C band, Ku band and Ka band. The higher the frequency, the smaller will be the antenna size.

In Mobile IP, the mobile device will have two addresses: Home address and care-of-address. When the mobile device moves from one network to another network, the packets will be forwarded to the mobile device using these addresses.

Asynchronous Transfer Mode (ATM) is an attractive packet switching technology that achieves fast packet switching with small packets of fixed size. ATM technology is an outcome of the developments in broadband ISDN. In ATM, each packet is called a `cell'. The cell size is 53 bytes - with 5 bytes header and 48 bytes of data.

Conversion of text into corresponding pronunciation is called transliteration. In English, 26 letters are mapped onto 42 phonemes - these are the smallest speech sounds. These phonemes are represented by special symbols. For English, 350 pronunciation rules are required to convert text into the corresponding pronunciation. Even with so many rules, not all the words are pronounced properly. Therefore, a dictionary of exceptions is required.

If your engineers are talking mumbo-jumbo, this book may help in deciphering.

Play while you play

ALL work and no play makes Jill a dull girl. So, here comes Mike McShaffry's Professional Game Programming - the ultimate reference with a complete coverage of programming commercially viable computer games. The back cover states that the book would teach you the nuts and bolts of the game-coding process; insider techniques for writing top-notch game code; 2D and 3D graphics techniques used by professional game developers; unique insight on critical algorithms you can't live without, debugging secrets; and key `gotchas' to avoid that can really hurt game development projects. Read on:

You can't design `fun'. Fun is a `tweakable' thing, not something that exists in a design document. You hope like hell that the original design will result in a fun game, but the first playable version frequently leaves you with the distinct impression that the game needs some more chilli powder and a little more time on the stove.

Any game programmer who wants to remain being a game programmer for very long quickly needs to master the art of developing great user interfaces so that players can better interact with their games. The trick to building successful interfaces is to make sure that the interface really matches the format and complexity of the game you are building.

Smart game programmers realise early on that some problems are harder than others. If you thought that creating a good flight simulator was a piece of cake, I'd tell you that the tough part isn't simulating the airplane, but simulating the ground. Games need enormous amount of data to suspend disbelief on the part of players.

Some relative newcomers to the middleware arena are physics engines. This software provides APIs to simulate the movements of 3D geometry under effects of gravity, friction, collision with other objects, and even soft body motions such as cloth. But check if you really need a physics engine. For instance, collision with simple shapes is a well-published problem with relatively simple solutions.

Perhaps having objects simply disappear after they've been hit is a good alternative to spending the annual salary of a good programmer on licensing fees.

Content complete is really a milestone that is pretty special to game development.

This stage focuses on completing and installing all the other game data: sound effects, speech, music, map levels, help, and anything else that isn't a part of the executable.

Content complete usually follows four to eight weeks after the code complete milestone.

Play by the book.

(Books courtesy: Wiley Dreamtech India P Ltd www.wileydreamtech.com)

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