A method for secure and efficient block cipher using white-box cryptography

Abstract

Nowadays many information should be protected securely. Generally, they are encrypted by cryptographic algorithm. A secret value is used as encryption key which must not be exposed as public. However, the key can be extracted by adversary using white box attack. In the white box attack, the adversary is supposed to have full control of the target program's execution environment. A White-Box Cryptography is introduced to protect key from white box attack. In the previous research, white box cryptography is applied to symmetric key encryption. Although they provide protection mechanism from extracting key, they have disadvantages that are low performance and difficulty of key update. In this paper, we mentioned White-Box AES proposed by Chow et al. and improve its low performance and key update problem. We adopted composite mode using White-Box AES and Standard AES. Our scheme shows almost same performance with Standard AES and provides dynamic key approach effect. Moreover, it has a CPA-secure property and can be constructed for CCA-secure scheme with Message Authentication Code.