Shri Ramswaroop Memorial University

Shri Ramswaroop Memorial University. 1. SRMU Lucknow YouTube.

Table of Contents. 2. Introduction Techniques for Encryption History Diffie -Hellman Algorithm Security of the Diffie -Hellman Algorithm Uses Advantages Disadvantes Project Execution Screenshots Conclusion.

Introduction. 3. The first published public-key algorithm that defined public-key cryptography was published by Diffie and Hellman..

Techniques for Encryption. 4. • There are two basic techniques for encrypting information: • Symmetric Encryption (also called secret key encryption). • Asymmetric Encryption (also called public and private key encryption)..

History. 5. • The Diffie -Hellman algorithm was developed by Whitfield Diffie and Martin Hellman in 1976. • This algorithm was devices not to encrypt the data but to generate same private cryptographic key at both ends so that there is no need to transfer this key from one communication end to another..

Diffie -Hellman Algorithm. 6. The Algorithm Lets assume that there are two publicly known numbers: a prime number q and an integer α that is a primitive root of q..

Each side keeps the X value private and makes the Y value available publicly to the other side. Thus , X A is A’s private key and Y A is A’s corresponding public key, The same applies for B..

Diffie -Hellman Algorithm. 8. Alice Alice and Bob share a prime number q and an integer a, such that a < q and ais a primitive root of q Alice generates a private key XA such that XA < q Alice calculates a public key YA = OXA mod q Alice receives Bob's public key YB in plaintext Alice calculates shared secret key K = (YB)XA mod q Bob Alice and Bob share a prime number q and an integer a, such that a < q and a is a primitive root of q Bob generates a private key XB such that XB < q Bob calculates a public key YB = a B mod q Bob receives Alice's public key YA in plaintext Bob calculates shared secret key K = (YA)XB mod q.

Example: Lets take q = 353 and a primitive root of 353, α = 3 . A and B select private keys X A = 97 and X B = 233, respectively ..

A computes K = (Y B ) XA mod 353 = 248 97 mod 353 = 160. B computes K = (Y A ) XB mod 353 = 40 233 mod 353 = 160 . an attacker would have available the following information: q = 353; α = 3; Y A = 40; Y B = 248..

While it is relatively easy to calculate exponentials modulo a prime, it is very difficult to calculate discrete logarithms . For large primes, the latter task is considered infeasible ..

Uses. 12. Aside from using the algorithm for generating public keys, there are some other places where DH Algorithm can be used: Encryption: The Diffie Hellman key exchange algorithm can be used to encrypt. One modern example of it is called Integrated Encryption Scheme, which provides security against chosen plain text and chosen clipboard attacks. Password Authenticated Agreement: When two parties share a password, a password-authenticated key agreement can be used to prevent the Man in the middle attack. This key Agreement can be in the form of Diffie -Hellman. Secure Remote Password Protocol is a good example that is based on this technique..

Contd ….. 13. Forward Secrecy: Forward secrecy-based protocols can generate new key pairs for each new session, and they can automatically discard them when the session is finished. In these forward Secrecy protocols, more often than not, the Diffie Hellman key exchange is used..

Adavantages. 14. The sender and receiver have no prior knowledge of each other. Communication can take place through an insecure channel. Sharing of secret key is safe..

Disadvantages. 15. A problem with asymmetric encryption, however, is that it is slower than symmetric encryption. It requires far more processing power to both encrypt and decrypt the content of the message..

Project Execution Screenshots. 16. blob:https://web.whatsapp.com/56b268e4-8b9d-43a8-87ee-45b662480dc5.

Contd ….. 17. Diffi-Hellman Algorithm Alice public Value G: Alice private value x: SENDER Enter our Message Encryption Generate Key Encrypted Message Bob value p: Bob private value RECEVIER Enter key Submit Receive Message Decryption.

Contd ….. 18. Diffi-Hellman Algorithm Alice Alice private value x: SENDER Enter our Message hello mike Encryption Generate Encrypted Message Send Key Bob p: Bob private value RECEVIER Enter key Submit Receive Message CE•cryption.

Conclusion. 19. The Diffie Hellman key Exchange has proved to be a useful key exchange system due to its advantages. it is really tough for someone snooping the network to decrypt the data and get the keys, it is still possible if the numbers generated are not entirely random. Also, the key exchange system makes it possible to do a man in the middle attack; to avoid it, both parties should be very careful at the beginning of the exchange..

Thank You…. 20.