[글쓴이:] comibear

Coppersmith Method – RSA
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/ 미분류Read More →: Coppersmith Method – RSAWhen we study about RSA cracking, we could hear a lot about the Coppersmith Method. Briefly, when we want to get some roots against the polynomial, we can compute it simply (not simple to me, simple to computer lol). But if the polynomial is on modulus field, it changes into a completely different problem. So…

암호분석경진대회 후기 (in Korean)
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/ 미분류Read More →: 암호분석경진대회 후기 (in Korean)이번에 암호르파티 라는 팀명으로 암호분석경진대회 (cryptocontest.kr) 를 나가게 되었다.총 6개의 문제가 나왔는데, 1 ~ 4번은 고등부 수준의 문제, 그리고 5, 6번은 대학부 수준의 문제라고 한다.각각 문제들을 간략히 설명해 보자면 다음과 같다. 1 ~ 4 번의 문제들은 2 ~ 3일 정도 소요되었던 것 같고, 5 ~ 6번은 자세하게 문제를 이해하느라 조금 더 걸렸던 것 같다. 나는…

Differential Cryptoanalysis
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Read More →: Differential CryptoanalysisPresentation on my univ lol 🐯 Here is the paper which I saw for presentation 🙂 If I solve CTF problems related to difference analysis later, I could add posts here XD.

Factoring with Gaussian Integer
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Read More →: Factoring with Gaussian IntegerGaussian Integer is represented as $a + bi$. Simply can think as complex number with integer coefficients. Surprisingly, we can use this Gaussian integer to factorize the numbers. Let’s see some challenges using Gaussian integer. Euclidean RSA – [nullcon CTF] The code is simple enough, just generate the RSA key and make the variables $a,…

Mapping points into independent Group
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Read More →: Mapping points into independent GroupMapping is very very important method. The representative example of mapping is isogeny. Isogeny is defined with mapping function, and other many concept in math uses mapping. Rather than addressing the whole thing in this article, I plan to post with significance to come up with this mindset. The challenge which made me think about…

Factoring N by associated prime factors
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Read More →: Factoring N by associated prime factorsFactoring N is very very important problem for RSA crypto system. If we could factor N, the crypto system will be cracked and can be easily decrypted. So it is safe to say that the difficulties of RSA encryption systems depend on factorization. In some CTF challenges such as sus – [ImagianryCTF 2023] and cry…

Cracking Python Random Module
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Read More →: Cracking Python Random ModuleWe often see Python random modules in CTF and other open sources. It is very useful if used well, but at the same time it has serious vulnerabilities (such as predicting random value). Because of the algorithm named Mersenne Twister used in python random module. Before we begin, I would like to inform you that…