Crpto ppt
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This document provides an overview of cryptography. It discusses security threats and goals, then defines cryptography as using mathematics to encrypt and decrypt data. It describes basic terms like plaintext, encryption, ciphertext, and decryption. The document outlines symmetric and asymmetric key cryptography, and examples of techniques like transposition ciphers, substitution ciphers, stream ciphers, and block ciphers. It concludes that cryptography should be used to implement network security and prevent data leakage through encryption and decryption techniques.
Crpto ppt
- 1. Submitted by- ASMITA PAL 0201CS141017 Submitted to- Asst. Prof. Deepti Tamrakar Dept. of Computer Science & Engg.
- 2. Overview Security Security Threats Security Goals What is Cryptography Basic Terms Encryption & Decryption Transmission Techniques Categories of Cryptography Comparison Conclusion
- 6. What is Cryptography? • Cryptography is the science of using mathematics to encrypt and decrypt data. • Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.
- 7. Basic Terms • Plaintext: Data that can be read and understood without any special measures. • Encryption: The method of disguising plaintext in such a way as to hide its substance is called encryption. • Cipher text: Encrypting plaintext results in unreadable gibberish called cipher text. • Decryption: The process of reverting cipher text to its original plaintext is called decryption. • Key: some secret piece of information that customizes how the cipher text is.
- 8. Basic Terms cont. • Cryptanalysis: The art of breaking ciphers, i.e. retrieving the plaintext without knowing the proper key. • Cryptographers: People who do cryptography. • Cryptanalysts: Practitioners of cryptanalysis. • Cryptology: The branch of mathematics that studies the mathematical foundations of cryptographic methods.
- 10. Why Use Cryptography? • For “secret writing” • To establish a shared secret when other people (eavesdroppers) are listening. • TYPES Mainly classified into two types: 1. Symmetric key cryptography 2. 2. Asymmetric key cryptography
- 14. Transposition Cipher • In classical cryptography, a transposition cipher changes one character from the plaintext to another i.e. the order of the characters is changed.
- 15. Substitution Cipher • Substitution cipher is a method of encryption by which units of plaintext are substituted with cipher text according to a regular system.
- 16. Stream Cipher • A Stream Cipher is a symmetric or secret key encryption algorithm that encrypts a single bit at a time. With a Stream Cipher, the same plaintext bit or byte will encrypt to a different bit or byte every time it is encrypted. • e.g. : Plain text: Pay 100 Binary of plain text: 010111101 (hypothetical) Key: 100101011 -- --- Perform XOR ____________________ Cipher text 110010110 ---- -
- 17. Block Cipher • Block cipher technique involves encryption of one block of text at a time. Decryption also takes one block of encrypted text at a time. Length of the block is usually 64 or 128 bits. • e.g. : Plain text: four and five Four and five Key Key Key wvfa ast wvfa --- cipher text
- 18. Asymmetric Key Cryptography Public key cryptography is an asymmetric scheme that uses a Pair of keys for encryption: a Public key, which encrypts data, and a corresponding Private key (secret key) for decryption.
- 20. Conclusion • Cryptography, being an art of encrypting and decrypting confidential information and private messages, should be implemented in the network security to prevent any leakage and threat. • It can be done by using any of these techniques discussed above for fortifying the personal data transmission as well as for secure transaction. • By using of encryption & decryption techniques a fair unit of Confidentiality, Authentication, Integrity, Access control and Availability of data is maintained.