ITEPC 02 - Decrypting Historical Ciphers

(Faculty supervisor:Prof. DING, Cunsheng and Prof. GOLIN, Mordecai J.)

Objectives and Description:

Codes or ciphers are methods for transforming messages (called plaintext) into unreadable text (called ciphertext) using a secret one-to-one function. The original message can be recovered from the ciphertext using the inverse of the one-to-one function. The process of transforming a piece of message into a piece of ciphertext is called encryption, and the inverse process is referred to as decryption. The Roman Emperor JULIUS CAESAR's code will transform the message "LOVE" into the ciphertext "ORZH".

Codes and ciphers have been used since ancient times (c. 1900 B.C.). Below is the "Dancing Men Cipher (about 1587)".

The picture on the right side above shows ciphertext on a gold bar from China (about 1930's), which is still not decrypted. Ciphers have played a very important role in the two world wars.

The left one above is the Japanese cipher machine used in World War II, and the right one is called SIGBA which was used by the US Army in World War II and was the only cipher machine remain completely unbroken during that time. During the World War II, 60 Japanese navy codes and many German codes were broken (decrypted) by the Allies. This made significant contributions to the defeat of the Japanese and Germans in the World War II.

Traditionally, ciphers are crucial for diplomatic and military communications. Nowadays, they are widely used. Police organizations, government officials, banks, business companies, gangsters, mafia, and ordinary people are using ciphers because ciphers are incorporated in our mobile phones, fax machines and computers. Without ciphers on-line banking and shopping would not be possible. Hence ciphers have changed our daily life.

Language of instruction:

English

Software tools / programming languages involved:

Not essential. Will be determined after conversation with students as to what languages they know.

Deliverables:

In this project, you will be asked to decrypt a sophisticated cipher. Details of the cipher and background information will be given later.

This project is divided into three phases. In the first phase, you will attend a few lectures giving basic knowledge of ciphers and their history and will be asked to read some accompanying references. In the second phase, you will read one reference on decrypting ciphers. In the last phase, you will be given the cipher encoded message and be asked to decrypt it.

Things students will learn:

By working on this project, you will learn the basics of the design and analysis of ciphers. You will also obtain knowledge about several fascinating areas of mathematics.

Prerequisites:

An interest and good capability in school mathematics and some basic experience in programming (no specific language is needed). Although the project will need some new mathematics, it is self contained and the new knowledge needed will be provided in handouts and a few introductory lectures.

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