Abstract: A concrete symmetric cipher scheme SCB, which can be easily implemented in both software and hardware, is presented. It combines the superiorities of both block and stream ciphers. From the viewpoint of one single block encryption, SCB is a kind of reiterative block cipher. However, the attackers will have to face with a onetimepad like cipher scheme if they do not carry through an exhaustive key search attack.

Key words: Data Encryption, Symmetric Key Encryption Algorithm, the Crossbreed of Block and Stream Ciphers, OneTImePad