# All Questions

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### Malleability of homomorphic encryption

El Gamal is a malleable homomorphic encryption system, so is Rabin. Are all homomorphic encryption systems malleable? Or are there any that are not malleable? Thanks!
2answers
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### What would be the best plain text Cryptography method without the use of a computer? [closed]

What would be the best Cryptography method without the use of a computer? This could be a list of the current options available, that could be used without the use of a computer ...
1answer
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### Polynomial division hardware implementation

I am beginning the implementation of the polynomial binary division algorithm now as I understood i will be checking the MSB bit if 1 to XOR and shift the sum if 0 i will only shift. What I am not ...
1answer
58 views

### RSA Protocol behind Yaksha Security System

So I'm reading over the Yaksha Security System and see it is based on the RSA cryptosystem and a centralized server, easy enough. What I'm slightly confused on is the math behind the related keys. It ...
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In the Cocks IBE scheme it is required for the hash function, that the Jacobi symbol of its output and the universally available moduls $n = p*q$ is $+1$, so: $\Big(\frac{H(ID)}{n}\Big) = ... 1answer 64 views ### what is the benefit of lcm in cryptography? [closed] what is the benefit of lcm in cryptography? and what is the effect of lcm on public key? note * lcm = Least common multiple thanks 0answers 62 views ### processing time for multiplication and exponentiation in pairing base cryptography I'm using the Boneh-Boyen-Shacham signature scheme and want to estimate complexity in my scheme. As reported in "Scott M., Efficient Implementation of Cryptographic pairings", if we set parameters ... 0answers 52 views ### CAST-256 (CAST6) versions or S-Boxes Are there different versions of CAST-256 - also known as CAST6 - available? Are there different S-Boxes available for CAST-256? If there are different versions or S-Boxes what identifier should I use ... 2answers 132 views ### Voting system validation I'm developing an application to run elections. A voting system. I would like to give the ability to the voters to check later if their vote were correct computed/casted. assumptions: each user has ... 0answers 54 views ### Are there any proofs of the SHA1 compression function's (second-)preimage resistance? Why is SHA1 preimage-resistant? The best reference that I can find is Rogaway & Shrimpton's 2009 paper, and I'll use their definitions. The kind of preimage resistance that is wanted is aPre. ... 1answer 46 views ### Explanation of the Fiat-Shamir heuristic The Wikipedia page on the topic (http://en.wikipedia.org/wiki/Fiat%E2%80%93Shamir_heuristic) is completely useless as it only explains what it is and not how it works. I looked at the original paper ... 1answer 69 views ### Fermats Little Theorem, primitive root [closed] So I am studying for finals and I am not able to solve the problem: Let$ p = 3 * 2^{11484018}- 1 $be a prime with 3457035 digits. Find a positive integer$x$so that$2^x\equiv 3\pmod p$Any ... 1answer 65 views ### Does it necessary the public key is prime number in RSA algorithm? I read some books talk about RSA cryptography but I did not understand something when choosing a public key$e$Sometimes the condition is$1<e<\phi(n)$Where$\phi(n) = p-1 * q-1$also ... 1answer 45 views ### Is a strong block cipher usable as a strong sponge function? From the literature, it looks like the security proofs of sponge functions depend on how well they approximate a random permutation, Since a block cipher also ideally behaves like a random permutation ... 1answer 78 views ### CBC-R when IV unknown I've read the CBC-R description from Rizzo & Duong but am having trouble understanding the sequence of steps that would be taken when the IV is unknown and is not included with the ciphertext. ... 1answer 121 views ### Looking For Additively Homomorphic Encryption I have a construction that requires as primitive an Additively Homomorphic Encryption scheme that does not rely on hidden group order, meaning I can't use Paillier. I now have two different ... 1answer 34 views ### Use of the master key in Delerablée's Identity-based Broadcast Encryption I'm reading “Identity-Based Broadcast Encryption with Constant Size Ciphertexts and Private Keys” by Cécile Delerablée. On page 207, the encryption process needs$\gamma$which is part of the master ... 0answers 49 views ### Polynomial Inversion over Galois Field Hello guys I am looking to calculate the Inverse of a given polynomial in Galois field I have found the little Fermat's algorithm and the Itoh-Tsujii I am getting a bit confused with both algorithm ... 1answer 120 views ### Timelock puzzle improvment I came across this question with this answer about a cryptographic timelock-puzzle that needs approximately 30 years to be solved. There is also an explanation with source code for that puzzle ... 1answer 49 views ### MD-compliant hashes don't really accept arbitary length input, do they? When people talk about hash functions, they usually say that they accept arbitrary-length input, but if you actually look at the padding (eg MD-strengthening padding), you see it's like ... 1answer 44 views ### HMAC ipad and opad choice It is written in the HMAC paper that the$ipad=0x36$and$opad=0x5c\$ were chosen such that it maximize the Hamming-Distance of the part of the key used in the inner and outer part of the HMAC process. ...

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