Category: 4. Public Key Encryption

In ElGamal system, each user has a private key x. and has three components of public key − prime modulus p, generator g, and public Y = gx mod p. The strength of the ElGamal is based on the difficulty of discrete logarithm problem. The secure key size is generally > 1024 bits. Today even 2048 bits long key…

The generation of an ElGamal key pair is comparatively simpler than the equivalent process for RSA. But the encryption and decryption are slightly more complex than RSA. ElGamal Encryption Suppose sender wishes to send a plaintext to someone whose ElGamal public key is (p, g, y), then − C1 = gk mod p C2 =…

An example of generating RSA Key pair is given below. (For ease of understanding, the primes p & q taken here are small values. Practically, these values are very high). de = 29 × 5 = 145 = 1 mod 72 Encryption and Decryption Once the key pair has been generated, the process of encryption…

The security of RSA depends on the strengths of two separate functions. The RSA cryptosystem is most popular public-key cryptosystem strength of which is based on the practical difficulty of factoring the very large numbers. If either of these two functions are proved non one-way, then RSA will be broken. In fact, if a technique…

This cryptosystem is one the initial system. It remains most employed cryptosystem even today. The system was invented by three scholars Ron Rivest, Adi Shamir, and Len Adleman and hence, it is termed as RSA cryptosystem. We will see two aspects of the RSA cryptosystem, firstly generation of key pair and secondly encryption-decryption algorithms. Generation of RSA Key Pair…

Public Key Cryptography Unlike symmetric key cryptography, we do not find historical use of public-key cryptography. It is a relatively new concept. Symmetric cryptography was well suited for organizations such as governments, military, and big financial corporations were involved in the classified communication. With the spread of more unsecure computer networks in last few decades,…