Modified ElGamal Elliptic Curve Cryptosystem using Hexadecimal Representation

Data encryption is an important issue and widely used in recent times to protect the data over internet and ensure security. One of the mostly used in public key cryptographies is the Elliptic Curve Cryptography (ECC). A new modified method has been proposed to encrypt/decrypt data using ECC in this paper. This modification converts each character of the plaintext message to its hexadecimal ASCII value of two digits, then separates the value into two values. After that, the transformation is performed on each value into an affine point on the Elliptic Curve E. This transformation is used to modify ElGamal Elliptic Curve Cryptosystem (EGECC) to encrypt/decrypt the message. In modified method, the number of doubling and adding operations in the encryption process has been reduced. The reduction of this number is a key point in the transformation of each character into an affine point on the EC. In other words, the modified method improved the efficiency of the EGECC algorithm. Moreover, using the hexadecimal ASCII value makes EGECC more secure and complicated to resist the adversaries.