June 23, 2007

Ever felt the need of a covert tongue? Many times indeed, and the professionals need it even more. I bet many of us use it already, in our own style, or what do you think the so many signs, symbols, names and weird languages we derive are meant for? Don’t get surprised as there is a separate branch of learning devoted solely to assure furtive and absolutely effective communication.

Cryptology is a science concerned with data communication and storage in secure and usually secret form. It encompasses both cryptography and cryptanalysis.

The word
The term cryptology is derived from the Greek kryptós (“hidden”) and lógos (“word”). Only legitimate users are able to transform information by virtue of a secret key or keys — i.e., information known only to them.

In modern times, cryptography is considered to be a branch of both mathematics and computer science, and is affiliated closely with information theory, computer security, and engineering.

Cryptograhy
Until modern times, cryptography referred almost exclusively to encryption, the process of converting ordinary information (plaintext) into unintelligible gibberish (i.e., ciphertext) by means of a cipher or code, or both. Decryption is the reverse, moving from unintelligible ciphertext to plaintext.

Cipher
A cipher (or cypher) is a pair of algorithms which perform this encryption and the reversing decryption. The detailed operation of a cipher is controlled both by the algorithm and, in each instance, by a key. This is a secret parameter (known only to the communicants) for a specific message exchange context. Keys are important as ciphers without variable keys are trivially breakable and so rather less than useful for most purposes.

Code
In cryptography, code means the replacement of a unit of plaintext (i.e., a meaningful word or phrase) with a code word (for example, ‘apple pie’ replaces ‘attack at dawn’).

Certain codes, like Morse code, were developed before the radio and telephone to make it easy to send messages to great distances. Morse code could also be used to allow two ships to communicate through the use of blinking signal lights. Even today Morse code is used in radio because the beeps sometimes can get through heavy static that voice communications cannot. Codes are no longer used in serious cryptography — except incidentally for such things as unit designations (e.g., 'Bronco Flight' or Operation Overlord) — since properly chosen ciphers are both more practical and more secure than even the best codes, and better adapted to computers as well.

Past and the present
Before the modern era, cryptography was concerned solely with message confidentiality (i.e., encryption) — conversion of messages from a comprehensible form into an incomprehensible one, and back again at the other end, rendering it unreadable by interceptors or eavesdroppers without secret knowledge (namely, the key needed for decryption of that message).

In recent decades, the field has expanded beyond confidentiality concerns to include techniques for message integrity checking, sender/receiver identity authentication, digital signatures, interactive proofs, and secure computation, amongst others.

Cryptanalysis
The science of cryptanalysis deals with “breaking” and reading secret codes and ciphers. The goal of cryptanalysis is to find some weakness or insecurity in a cryptographic scheme, thus permitting its subversion or evasion. Cryptanalysis might be undertaken by a malicious attacker, attempting to subvert a system, or by the system’s designer (or others) attempting to evaluate whether a system has vulnerabilities, and so it is not inherently a hostile act.

It is a commonly held misconception that every encryption method can be broken. In connection with his World WarII work at Bell Labs, Claude Shannon proved that the one-time pad cipher is unbreakable, provided the key material is truly random, never reused, kept secret from all possible attackers, and of equal or greater length than the message.

Encryption and encoding devices
The earliest forms of secret writing required little more than local pen and paper analogs, as most people could not read. As time went on, mechanical devices were invented to make encryption and decryption easier. By the early part of the twentieth century, electro-mechanical encryption machines were common. One famous device, called “the Enigma”, was used by the Germans during WWII.

The introduction of computers has revolutionised cryptography. Computers can be used to make ciphers far more unbreakable than could ever be done by any means. Computers can also be used to break codes that in the past might have seemed unbreakable. So far, it is far easier for a computer to encrypt a message than to break it.

In today’s life
Cryptography is used in many applications encountered in everyday life; security of ATM cards, computer passwords, and electronic commerce all depend on cryptography.

I hope all this text does motivate you to develop your very own codes. I use it too, as it makes gossiping all the more easy and safe. Try it yourself, and I assure you’ll love it!