The Graph and Algebra (GA) Research Group, Mathematics Department, FMIPA UNEJ, held a public lecture with resource person Prof. Dr. I Wayan Sudarsana from Tadulako University (19/10). Raising the theme of Information Systems Security: Cryptography and Graphic Labeling, Prof. Wayan started his public lecture by talking about security that is often encountered in everyday life. “You all must often make transactions at the bank, and that requires the security of special information such as a pin or token. This security process is usually known as encryption, which contains cryptography in it,” began Prof. Wayan.

Previously, Chairman of KeRis Dr. Kristiana Wijaya expressed her great appreciation to Prof. Dr. I Wayan Sudarsana, who was pleased to give a public lecture. “KeRiS GA and I express our high appreciation amidst his busy agenda at one of the universities in Jember. Prof. Wayan is pleased to give a public lecture for mathematics students,” said Dr. Kristiana. There were also lecturers in the Mathematics Department, especially members of KeRiS GA and the Combinatorics, Graph Theory, and Network Topology (CGANT) team led directly by Prof. Dafik.

Prof. Wayan continued his public lecture by introducing an encoding system using a series of numbers using the alphabet plus spaces. “This technique is commonly known as encoding, which aims to obscure the message or encryption and translate the message or decryption,” he explained. And it turns out that this was used more than 2000 years ago by Julius Caesar for correspondence purposes, known as the sliding code.

Matrix ciphers are also presented, where the original message obtained is the result of multiplying the inverse of the encoding matrix and the message matrix. “However, this matrix code has a weakness if this technique is published because it can be attacked with the help of computers,” said Prof. Wayan. The opposite is true with today’s encodings, utilizing the concept of prime number factorization, which will produce sophisticated encodings that have been widely used by secret agents.

The idea of prime number factosization was expressed by Ron Rivest, Aldi Shamir, and Len Adleman from MIT, which is popularly known as the RSA technique. “If two prime numbers are multiplied, it will be easy to calculate, but if it is a composite number, which is the product of a number of prime numbers, then it is difficult to factor it, especially if the number is large,” he continued. At the end of the event, Prof. Wayan said that the current trend in encoding techniques is to use graph labeling. And from today’s lecture discussion, he invited students to implement network-based information security in their final projects.