Abstract

This study aims to present a modified technique for signing constant messages. In general, intruders may often steal the digital signature of a constant message with relative ease. Assuming there is a constant message that must always be signed by the signer, the digital signature must equally have a constant value. If it is communicated through an insecure channel to the recipient or verifier and is intercepted along the way by attackers, they can assume the identity of the signer and use this signature for authentication. In fact, the proposed method, Digital Signature Algorithm for Constant Message (DSACM) and DSACMV2, are the result of the combination between RSA and OTP. In addition, OTP is selected for signing and validating procedures in which the secret key must be regenerated for each process. Thus, the ciphertext is constantly changing, but the message remains fixed. Moreover, RSA is chosen to protect the transmission of the secret key across an insecure channel. The experimental findings indicate that DSACM and DSACMV2 are suitable for signing a message with a constant value because the signature is an undetermined value. Although it takes two encryption procedures and two decryption processes, the time required to generate the secret key and perform the exclusive or operation increases little. In addition, the proposed methods have the benefit that the constant message is not modified. In fact, it must be combined with an integer such as a timestamp and a random number for the other techniques for changing the ciphertext, and it cannot be signed a single time if its length exceeds the private key.