Due to the rapid growth of computer networks, more sensitive information is being exchanged over such networks. Securing information from unauthorized parties has become a critical issue in the field of securing information technology. DNA cryptography is a promising technology in the cryptographic field which enables users to encrypt data securely based on the real biological DNA strands. Although there are many DNA encryption algorithms, there is still room for security improvement. In this paper, we introduce a symmetric DNA binary cryptography algorithm to encrypt and decrypt plaintext information. the contribution of this paper are twofold: First, we introduce a mathematical algorithm to generate strong secret key from the DNA of different multiple living creatures. Second, the encryption process is implemented using another 16 keys which randomly generated from the secret key. The efficiency and confidence of the proposed algorithm is examined in terms of encryption and decryption time, avalanche effect and the resistance of the secret key against the attack.