Overcoming DES Key-Length Limitations: A Novel Approach to Position Conversion and 128-Bit Key Encryption

Abstract

The Data Encryption Standard (DES) is an algorithm designed to protect information by converting it from a readable form, known as plaintext, into an unreadable form, known as ciphertext. This process is called encryption, whereas the reverse process, which translates ciphertext back into plaintext, is referred to as decryption. The primary weakness of DES lies in its relatively short key length, which allows all possible keys to be exhaustively tested in a relatively short time. This research aims to address that weakness by designing a derivative of the DES algorithm with a key length exceeding 64 bits. The findings of this study indicate that the position conversion table within DES plays the most critical role in determining the key length that the algorithm can process. Consequently, this research focuses on developing a pattern for position conversion labeling, with the expectation that it can be utilized to construct a new position conversion table capable of handling keys longer than 64 bits. The final result of this study is the development of a new DES-derived algorithm with a 128-bit key, named DES-Aku. However, DES-Aku is not merely a derivative of DES; it also serves as a protocol for constructing position conversion labels within DES. As an algorithm, DES-Aku successfully performs character encryption using a 128-bit key, and as a protocol, DES-Aku successfully demonstrates a pattern for constructing position conversion tables in DES, which can further be utilized to develop new position conversion tables for keys exceeding 128 bits.