Data security is an important issue in computer networks and cryptographic algorithms are essential parts in network security. In this paper a new block-ciphering algorithm, JEA K-128 (for Jamal Encryption Algorithm with a Key of length 128 bits) is described. JEA K-128 is a symmetric block cipher suitable for hardware or software implementations. JEA K-128 has a 64-bit word size, 4-rounds, and 128-bit is the length of the secret key. New cryptographic features in the authors' work include the use of many successive XORing for the plaintext with sub-keys, and the use of multiple multiplexers in sub-keys generator.