This paper aims at showing that Physics is very close to the substitution-diffusion paradigm of symmetric ciphers Based on this analogy, we present a new Cellular Automata algorithm, termed Crystal, implementing fast, parallel, scalable and secure encryption systems Our approach provides a design principle to ensure an invertible dynamics for arbitrary neighborhood Thus, several variants of our CA can be devised so as to offer customized encryption-decryption algorithms Considering larger data blocks improve both security and speed (throughput larger than 10Gbps on dedicated hardware).