Digital cryptography relies greatly on randomness in providing the security requirements imposed by various information systems. Just as different requirements call for specific cryptographic techniques, randomness takes upon a variety of roles in order to ensure the proper strength of these cryptographic primitives. This paper presents a 64-bit random number generator with a high generation speed and a good random sequences by employing the RC5 encryption algorithm round functions with some changes in the usage
of the key, where two keys have been used with an initial vector to start the sequence generator. This generator can be used as a keys generator for any security system or to generate an intermediate password for signing process, and it can be adapted in many other applications, such as random pattern generation, games, etc. Examining the sequences shows great results in terms of randomness and security by achieving a difference near 0.5, this value is the best result, and a high undependability on the previous generated sequences by also achieving a difference more than 0.5, frequency, serial and run test came out with a near optimality results.