A Double Key-Based Public-Private Key Encryption-Decryption Process for Secured Message Transaction

Abstract

In modern communication age, security of electronic message transaction is the demand of time. It is most essential in various aspects. Currently a large amount of sensitive data is transmitted over the open network or internet or other communication channels on a daily basis. Without strong security, we cannot protect these sensitive information from malicious attacks. Currently, it is main concern to impose additional security services to the communicating message, communication channel and communicating participants. For this, a better approach for electronic message transaction system has been developed using Python programming language. It performs electronic message transactions with all the fundamental security requirements, which are confidentiality, integrity, authentication and non-repudiation for both communicating message and communicating participants. To do this, simple cryptographic encryption and decryption techniques are used to the communicating messages. At first message is encrypts with the private key of sender PRa and the output is again encrypts with a shared secret key K1 that generates cipherext, which is again encrypts with another shared secret key K2 that generates a code that serves as message authenticator known as MAC, which is concatenates with the ciphertext and again encrypts them with shared secret key K1 that builds the new cphertext, which is again encrypts with the receiver’s public key PUb to produce final ciphertext that is to be send to the intendent recipient. In the receiving end, to retrieve the message, receiver at first decrypts the received information with his private key PRb and again decrypts with the shared secret key K1 that gives the ciphertext and MAC of the ciphertext, and then only decrypts the MAC to generate a new ciphertext′ and compare the new ciphertext′ with the received ciphertext that ensures the ciphertext authentication as well as message authentication; if ciphertexts are found same, then decrypts the ciphertext with shared secret key K1 and again decrypts with the sender public key PUa and retrieve the message; otherwise discard it. This technique can be applied anywhere of electronic communications in a secure fashion.