4

RSA is really very slow compared with symmetric ciphers. You can check this yourself running e.g. openssl benchmark: openssl speed rsa On my machine (and with openssl 1.1.1a) I get Doing 2048 bits public rsa's for 10s: 330640 2048 bits public RSA's in 10.00s so we can do ~33k encryptions per second and the size of the encrypted block is less than the ...


2

Say, $X= a\cdot b$, where $(a, b) \in Z_q^*$ and $q$ is a large prime. If $X$ is given, then what is the complexity (or hardness) of finding $a$ and $b$? If the multiplication is done within $Z_q^*$, then it's easy - pick an arbitrary nonzero $a$ and compute $b = a^{-1}X$; you're done. You can compute $a^{-1}$ by either the Extended Euclidean method, or by ...


1

First of all, this idea is based on a misconception: "But most ransomware use the hybrid encryption approach and during that they make mistakes allowing security researchers to build decryptors." This is my opinion is not correct. The first ransomware used just symmetric encryption. Now if that symmetric key is left then it may be possible to retrieve it ...


1

The questions you're getting confused by are, indeed, confusing, but I think I figured out what's going on. Imagine a scenario where: A company want to issue exactly 10,000 numbered coupons; They are concerned that malicious parties will forge coupons. So they can't just naïvely number the coupons from 0 to 9999; instead, they wish to use some numbering ...


1

Not sure if I am correct about this, but let me give it my best. I do get that encoding numbers from 0 to 9999 you get 10000 possible encodings, what I don't get is that how to you get 20 digit encodings? As far as I understand with FPE you always get the same length so if you encode numbers from 0 to 9999 you'd get ciphers between the same values. It ...


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