SMS4 Encryption Algorithm for Wireless Networks
SMS4 is a Chinese block cipher standard, mandated for use in protecting wireless net- works, and issued in January 2006. The input, output, and key of SMS4 are each 128 bits. The algorithm has 32 rounds, each of which modifies one of the four 32-bit words that make up the block by xoring it with a keyed function of the other three words. Encryption and decryption have the same structure except that the round key schedule for decryption is the reverse of the round key schedule for encryption.