An efficient probabilistic public-key block encryption and signature scheme based on El-Gamal´s scheme

A modified El Gamal scheme is presented which provides both secrecy and signature simultaneously with a high information rate of w/w+2, where w is a predetermined number of plaintext blocks to be sent. The scheme provides a better information rate than the original El Gamal scheme does, and thus is very efficient to use in secure data communications. The security of the scheme depends on the difficulty of solving the discrete logarithms