CAR30: a new scalable stream cipher with rule 30. CAR30 is a new stream cipher that uses classical Rule 30 of Cellular Automata (CA) along with a Maximum Length Linear Hybrid CA. This design can be implemented efficiently both in hardware and software. It has a fast initialization algorithm that makes it suitable for small messages. The generic design of the cipher enables to scale up for any length of Key and IV. This paper describes the cipher with 128-bit Key and 120-bit IV and evaluates the security and implementation aspects of it. The main advantages of the proposed cipher are the flexibility of its design, good hardware throughput in comparison with state-of-the-art hardware oriented ciphers like Grain and Trivium and better software speed than the software oriented stream cipher Rabbit.