ABSTRACT
This paper aims to introduce a circular queue-based product cipher encryption algorithm in which the message or the plaintext is inserted into a series of circular queues where the letters in the circular queues are first replaced by some other letters including alphabets, numbers, or special characters and then the letters shift in a particular direction within the queue. Each circular queue may or may not have a distinct shifting offset and direction. In this way, the plaintext is altered into an unintelligent text. The concept of the shifting of letters in a circular queue is driven from the real-life safe lock systems where multiple rotator locks are rotated in such a way that only a particular position of every rotator lock unlocks the safe. As the size of plaintext increases, the number of queues and the size of queues will increase which will consequently increase the randomization of letters.
