(In)Security of the AAβ Cryptosystem for Transmitting Large Data

The AAβ cryptosystem is a well-designed encryption scheme for securing a message (or plaintext) which could transmit large dataset than its key size. Nevertheless, the idea to transmit data larger than the specified condition is not a good idea. This work will explain why it is the case. As a result, we show that some most significant bit of the data can be recovered. In spite the very fact that the complete parameter cannot be recovered fully, anyway by leaks of its most significant bits, even of a very little amount could lead any cryptosystem insecure.