An Approach to Defense Dictionary Attack with Message Digest Using Image Salt

Hash algorithms have been widely used for cryptography. It has been impossible to decrypt the ciphertexts generated through hash algorithms, as an operation that damages the original text is performed. However, various methods of attack occurred over time after the algorithm was developed. The vulnerability of SHA1 (an old hash algorithm) has been revealed, and there has been a great deal of data available for dictionary attacks. Although the industry has been gradually refraining from using SHA1, it remains in use in some existing systems for various reasons. For example, when problems resulting from service interruption or mass update are critical, updating the encryption algorithm can be a burden. In this study, we aim to increase the complexity of ciphertexts by postprocessing hash ciphertext. For that, image salting techniques are used using two-dimensional array masking. This will allow the use of hash ciphertexts with increased complexity in some devices that are forced to use old hash algorithms for various reasons.