# A Basic RSA Encrypter

This is a small post about implementing a basic RSA encrypter to encrypt sections in an exe. We can use this to exchange exes with people. We will encrypt the section using the public key and the user has to use his private key to decrypt the exe. This can be applied in evading anti-viruses too.

I will use multiplication instead of an exponent. Since it would be easy to implement in few lines in assembly. However, this will allow breaking the private key easily hence the complete scheme is broken.

$Enc = (m*e) \text{ mod } N$

$Dec = (c*d) \text{ mod } N$

The correctness of this scheme depends on the fact that

$Dec(Enc(m)) = (m*e*d) \text{ mod } N = m \text{ mod } N$

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# eLearnSecurity Courses

With the competitiveness of the infosec industry, security training is definitely needed. Let me share my story. Back in 2013 I heard about eLearnSecurity. Those days the only courses was Penetration Testing Professional and Penetration Testing Student. But I didn’t have enough money to sign up since I was 16 years old. With the pocket money I had, I signed up for the Penetration Testing Student course since I was curious about the material. I was amazed by their teaching techniques. Everything was so clearly written. After that I had to enter university and I had no time to concentrate on the things I like to do. Gradually eLearnSecurity started developing specialized courses starting from Web Application Penetration Testing and next came the Extreme edition of this. Meanwhile, they launched a course on reverse engineering too which I was really surprised to see that course since it was the first ever course I saw on reverse engineering.
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