16-04-2012, 12:15 PM
INTERNET CRYPTOGRAPHY
cryptography.doc (Size: 53 KB / Downloads: 50)
INTRODUCTION
The Internet or the global Internet is the internationally connected network of computer networks with addresses that are administrated by IANA (Internet address and Naming Authority). It grew dramatically because anyone can connect to it and any one connected to it can connect others to it as well. Each site that connected to it, can become an Internet Service provider to other sites.
BASIC PROBLEM
Most people associate safety and security with physical protection, which is also true with computers. The safety of computers data relies heavily on the physical security of computer itself. This is problem of 'wired' world. Computer data travels from one computer to another, leaving safety of its protected physical surroundings.
BASIC TERMINOLOGY
The story begins: When Julius Caesar sent messages to his trusted acquaintances, he didn't trust the messengers. So he replaced every A by a D, every B by a E, and so on through the alphabet. Only someone who knew the ``shift by 3'' rule could decipher his messages.
ESSENTIALS OF CRYPTO
Crypto is a collection of techniques that transform data in ways that hard to mimic (or) reverse by someone who is not on secret. Here is an example of what happens after a and B agree that all messages shall be encrypted.
PRIVATE KEY CRYPTOGRAPHY
A private-key cryptosystem consists of an encryption system E and a decryption system D. The encryption system E is a collection of functions E_K, indexed by “keys” K, mapping some set of “plaintexts” P to some set of “ciphertexts” C.
CRYPTO ALGORITHMS
The following are the algorithms that are likely to be Encountered in products intending to provide strong crypto protection.
Data Encryption Standard
DES has the benefit of being a known quantity with familiar strenghs and weaknesses. In typical applications it is unlikely to be vulnerable to any attack of brute force. A technique called defferential cryptanalysis has been developed against DES, which is a technique for attacking a cipher by feeding it chosen plaintext and watching for patterns in ciphertext. The problem of DES today is its relatively short 546-bit key length.
CONCLUSION
Cryptography has emerged as the only alternative to protect Internet data and it does the job well.
New cryptographic products and technologies have been developed particularly for Internet applications.