Breaking Software Protection: ElGamal Signature Scheme

by Jamal Chahir
Oct. 8, 2017 0 comments INFOSEC Institute Encryption & Authentication

In today’s article, we will see a more advanced cryptosystem than the previous one: the ElGamal Signature scheme (not to be confused with ElGamal Encryption). So before you start reading this, read the first article for more details. Tools Needed The target file (CryptoChallenge2.exe) ELGAMALSiGNiT: An ElGamal signature scheme tool (requires dotNetFx4) PEiD IDA (Interactive Disassembler) OllyDBG RE-SIGS: IDA signature GODUP: OllyDBG plugin DLP Tool What is ElGamal? ElGamal is a public-key cryptosystem developed by Taher Elgamal in 1985. It has two variants: Encryption and Digital Signatures (which we’ll learn today). Its strength lies in the difficulty of calculating discrete logarithms (DLP Problem).