International Association
for Cryptologic Research

Data security and secrecy from unwanted applications are the subjects of the science known as cryptography. The advanced encryption standard algorithm is the most used and secure algorithm to encrypt data. The AES algorithm is based on the symmetric algorithm and uses a single key to encrypt and decrypt data. The AES algorithm uses 128 bits length of plain text with 128 bits, 192 bits, or 256 bits key size to encrypt data. Latin script uses ASCII codes, and a single byte represents each alphabet. Therefore, in 128 bits AES encryption, 16 characters can be encrypted each time. The other language script used the Unicode standard to represent their alphabets. In Unicode, at least 2 bytes are required to represent a character. Therefore, eight characters can be encrypted at a time. Also, there is no available S-box for Unicode characters. Therefore, a modified algorithm is proposed for Unicode to encrypt data. To use the AES algorithm in Unicode data, we need to convert the Unicode into character encoding, such as UTF-16. Nevertheless, In UTF-16, some Unicode characters have similar recurrent values. This paper demonstrates a modified AES algorithm to encrypt the Unicode script to reduce time complexity.