SAFER (Secure And Fast Encryption Routine) is a non-proprietary block cipher developed by Massey in 1993 for Cylink Corporation. It is a byte-oriented algorithm with a 64-bit block size and, in one version, a 64-bit key size. It has a variable number of rounds (maximum of 10), but a minimum of six rounds is recommended. Unlike most recent block ciphers, SAFER has slightly different encryption and decryption procedures. Only byte-based operations are employed to ensure its utility in smart card-based applications that have limited processing power. When first announced, SAFER was intended to be implemented with a key of length 64 bits and it was accordingly named SAFER K-64. Another version of SAFER was designed that could handle 128-bit keys and was named SAFER K-128.