Public Key Cryptography

Topics: Cryptography, Public-key cryptography, Digital signature Pages: 8 (1940 words) Published: September 15, 2010

Latika Arora , IT/06/321
Shri Balwant Institute of Technology
Pallri, Sonipat, Haryana

The present century has been one of many scientific discoveries and technological advancements. With the advent of technology came the issue of security. As computing systems became more complicated, there was an increasing need for security. Network Security is becoming more and more crucial as the volume of data being exchanged on the Internet increases. Security is a broad topic and covers a multitude of sins. Malicious people trying to gain some benefit, get attention or to harm someone intentionally cause most security problems. Network security problems can be roughly divided into 4 closely intertwined areas. They are: A. Privacy:

Privacy means that the sender and the receiver expect the confidentiality. The Transmitted message should make sense to only the intended receiver and to all others it is unintelligible. Authentication: Ensures that the sender and the receiver are who they are claiming to be B. .Data integrity:

Ensure that data is not changed from source to destination.
Ensures that the sender has strong evidence that the receiver has received the message, and the

receiver has strong evidence of the sender identity, strong enough such that the sender cannot deny that it has sent the message and the receiver cannot deny that it has received the message. This paper deals with cryptography, which is one of the methods to provide security. It is needed to make sure that information is hidden from anyone for whom it is not intended. It involves the use of a cryptographic algorithm used in the encryption and decryption process. It works in combination with the key to encrypt the plain text. Public key cryptography provides a method to involve digital signatures, which provide authentication and data integrity.

The goal of cryptography is to make it possible that two people to exchange a message in such a way that other people cannot understand. There is no end that number of ways this can be done, but here we will be concerned with the methods of altering the text in such a way that the recipient can undo the alteration and discover the original text.

A.Encryption and decryption

The basic functionality of cryptography is to hide information. Its operation typically includes two processes: • Encryption as the process of transforming information so that it is unintelligible to an intruder, and • Decryption as the process of transforming the encrypted information so that it is intelligible again. Data that can be read and understood without any special measures is called plaintext or clear text. The method of disguising plaintext in such a way as to hide its substance is called encryption. Encrypting plaintext results in unreadable gibberish called cipher text. We use encryption to make sure that information is hidden from anyone for whom it is not intended, even those who can see the encrypted data. The process of reverting cipher text to its original plaintext is called decryption.

Strong cryptography
Cryptography can be strong or weak, as explained above. Cryptographic strength is measured in the time and resources it would require to recover the plaintext. The result of strong cryptography is cipher text that is very difficult to decipher without possession of the appropriate decoding tool. How difficult? Given all of today’s computing power and available time—even a billion computers doing a billion checks a second—it is not possible to decipher the result of strong cryptography before the end of the universe.

B.How does cryptography work?
A cryptographic algorithm, or cipher, is a mathematical function used in the...

References: i. “Cryptography and Network Security, Principles and Practices”
--- (Third Edition)-William Stallings.
ii. “A Method for obtaining Digital Signatures and Public Key Cryptographic Systems.”
---Rivesp.R , Shamir.A and Adleman.L
iii. “Multiuser Cryptography Techniques.” -- Diffie.W and Hellman.M
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