# Certificate Generation in PKI: A New Approach.

## Date of Submission

December 2011

## Date of Award

Winter 12-12-2012

## Institute Name (Publisher)

Indian Statistical Institute

## Document Type

Master's Dissertation

## Degree Name

Master of Technology

## Subject Name

Computer Science

## Department

Applied Statistics Unit (ASU-Kolkata)

## Supervisor

Gupta, Kishan Chand (ASU-Kolkata; ISI)

## Abstract (Summary of the Work)

Cryptography is an art of storing and transmitting data in a form that only those it is intended for can read and process. It is a science of protecting information by encoding it into an unreadable format. Cryptography is an effective way of protecting sensitive information as it is stored on media or transmitted through network communication paths. Cryptography comes from Latin words â€Cryptâ€ meaning â€secretâ€ and â€Graphiaâ€ meaning â€writingâ€. So, Cryptography literally means â€secret writingâ€. The fundamental objective of cryptography is to enable two people, usually referred as Alice and Bob, to communicate over an insecure channel in such a way that an adversary, Oscar, can not understand what is being said. The information that Alice wants to send to Bob is called the â€plaintextâ€. Alice encrypts the plaintext using a predetermined key and sends the resulting â€ciphertextâ€ over the channel. Oscar, upon seeing the ciphertext in the channel by eavesdropping tries to determine the plaintext, but fails if the underlying cryptosystem is secure enough. Bob, who knows the encrypted key can decrypt the ciphertext and reconstructs the plain text. The Following schematic diagram shows the basic Cryptographic Model.The following are the main four goals of modern cryptography:â€¢ Confidentiality: Prevent an unauthorized exposure of the information. When transmitting data, one does not want an eavesdropper to understand the contents of the transmitted messages. The same is true for stored data that should be protected against unauthorized access.â€¢ Authentication: Prove that a message actually originates with its claimed originator. The recipient should be able to verify from the message, the identity of the sender, the origin or the path it travelled (or combinations) so to validate claims from emitter or to validated the recipient expectations.â€¢ Integrity: Prove that a message has not been altered in unauthorized ways. The recipient should be able to determine if the message has been altered.â€¢ Non-repudiation: Prevent an originator from denying credit (or blame) for creating or sending a message. The emitter should not be able to deny sending the message.Definition 1. [1] A Cryptosystem is a five tuple (P, C, K, E, D), where the following conditions are satisfied:1. P is a finite set of possible plaintext.2. C is a finite set of possible ciphertext.3. K, the keyspace, is a finite set of possible keys.4. For each K âˆˆ K, there is an encryption rule eK âˆˆ E and a corresponding decryption rule dK âˆˆ D. Each eK : P â†’ C and dK : C â†’ P are functions such that dk(eK(x)) = x for very plaintext x âˆˆ P.Note that to avoid ambiguous decryption, the function eK should be an injective function.Cryptography, depending on their encryption schemes can be broadly classified into two types, the symmetric (or secret key) schemes and asymmetric (or public key) schemes.

## Control Number

ISI-DISS-2011-270

## Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

## DOI

http://dspace.isical.ac.in:8080/jspui/handle/10263/6425

## Recommended Citation

Bhagat, Subhash, "Certificate Generation in PKI: A New Approach." (2012). *Master’s Dissertations*. 178.

https://digitalcommons.isical.ac.in/masters-dissertations/178

## Comments

ProQuest Collection ID: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:28843199