Hybrid cryptosystem combines symmetric algorithms and asymmetric algorithms. This combination utilizes speeds on encryption/decryption processes of symmetric algorithms and asymmetric algorithms to secure symmetric keys. In this paper we propose hybrid cryptosystem that combine symmetric algorithms VMPC and asymmetric algorithms RSA -CRT optimization. RSA -CRT optimization speeds up the decryption process by obtaining plaintext with dp and p key only, so there is no need to perform CRT

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... . The VMPC algorithm is more efficient in software implementation and reduces known weaknesses in RC4 key generation. The results show hybrid cryptosystem RSA -CRT optimization and VMPC is faster than hybrid cryptosystem RSA -VMPC and hybrid cryptosystem RSA -CRT -VMPC.