Question

Write a brief summary describing any encryption method not already mentioned in this chapter. In this summary, describe the history and origin of the algorithm. Compare the efficacy of this algorithm to other well-known algorithms.

Blowfish, AES, RC4, Serpent,3DES, RSA, PGP, Hashing, SHA, MD5 These are the method are already mentioned in this chapter.

Answer 1

A brief summary describing the Diffie-Hellman Key Exchange encryption method, its history, origin, and comparison of this algorithm's efficacy with other well-known algorithms:
It is also called Exponential Key Exchange. It is a public key protocol or cryptography method. This method is used when two parties who have no prior knowledge of each other both together, establish a shared secret key over an insecure network, such as the public Internet.
The algorithm is named after Whitfield Diffie and Martin Hellman. DH is the acronym. The method is used to securely exchange cryptographic keys over a public network or channel. It was published by Diffie and Hellman in 1976. It is the first publicly known work to have proposed the concept of a private and a corresponding public key. DH can be used for securing various Internet services. Hellman, Diffie, and Merkle are credited as inventors. Ralph Merkle contributed to the invention of public-key cryptography.

Efficacy: This algorithm lacks authentication. Data that uses this method is vulnerable to Man-In-The-Middle (MITM) attacks. It uses numbers that are raised to specific powers producing decryption keys on the basis of components never directly transmitted, thus making the job of a hacker mathematically overwhelming. It has been published the parameters used for many DH Internet applications at that time are not sufficiently strong for preventing compromise or hacks by very well-funded and organized attackers, for example, the security services of some countries.

A real-life exchange that uses large numbers for determination would be computationally expensive. Even modern supercomputers cannot compute in a practical amount of time.

The DH key agreement is a key-agreement protocol without any authentication. On the other hand, this protocol is secure against eavesdroppers, provided the cyclic group, G (must be large) and the generating element g in G both, are chosen properly.

Unlike other encryption methods, DH cannot be used for digital signature. DH can be easily used in a Denial of Service (DoS) attack. Also, it cannot be used for encrypting messages.

When compared to the RSA encryption method, DH cannot be used for asymmetric key exchange, whereas RSA is used for actual symmetric key encryption, provides a very slow key generation. RSA generates a public-private key pair, which is later used to exchange data. Whereas the DH algorithm is used for key-exchange, that uses primitive root, and later the sender and the receiver use that common key for subsequent data-exchange while using symmetric key encryption.