E-Business and sensitive Internet applications are growing very fast, so the needs to protect such applications are increased. Encryption algorithms play a main role in security. This work introduces a new key generation technique that can be used for enhancing the design of block cipher encryption algorithms, especially for DES to increase its key space; to be applicable in sensitive applications. This is based on the use of biometric key using the voice of speakers, extracting important features as formants and pitch of the speakers because it is unique for each one; in addition it applies crossover operations of genetic algorithm on biometric key to permute it. Finally it combines between stream ciphering and block ciphering algorithms (encryption of the crossover-biometric key using the RC4). The output Key-Stream bytes from the RC4 is then introduced to the DES algorithm to obtain the target ciphertext. The paper introduces also the idea of generating multi biometric keys by using different crossover operation types based on a specific time-slice. The paper introduces also the different steps for generating the Biometric-Crossover-Stream Key. Moreover the proposed DES provided added complexity due to the generation of new biometric key than normal DES; it is small, and can be neglected if one considers the trade-off between security and the complexity of the algorithm especially for the critical systems. The paper introduces a comparison between the proposed biometric keys and weak and semiweak keys; the biometric generated keys were neither semiweak nor weak keys so the generated keys are possibly acceptable.