Symmetric Key Distribution Model Using RSA-CRT Method

The problems that arise with the implementation information transmission of images are the large data size and the importance of information security. Both symmetric and asymmetric cryptography can be used to meet the security requirements of the messages being sent. A symmetric cryptosystem is faster, however, the distribution of the secret key to the recipient is vulnerable to security risks. While asymmetric cryptography is slower, it does not need special treatment for key distribution. Hence, the security risks associated with the distribution of symmetric keys can be overcome using asymmetric cryptography. Single asymmetric key encryption only provides confidentiality; it does not provide authenticity and integrity. In this paper, we propose a symmetric key distribution model that meets the requirements of confidentiality, authentication, and integrity using the Rivest Shamir Adleman (RSA)-Chinese Remainder Theorem (CRT) method. The proposed model consists of two stages of asymmetric cryptographic processes. The first step is to provide authentication and integrity to the symmetric key by decrypting the symmetric key using the sender's private key, the algorithm used is RSA modified with CRT. The second stage secures the symmetric key that has been authenticated by encrypting it using the recipient's public key using the RSA algorithm. Meanwhile, to accelerate the process of symmetric key distribution is done by reducing the size of CipherKey _Signature which is the result of the authentication-encryption process by converting from big integers to strings.