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Apr
16
comment Existence of a map $\phi:\mathbb{Z}_{N^2}^* \mapsto \mathbb{F} $
If we assume finite fields defined over congruent classes of prime numbers then $|\mathbb{Z}_F|=F-1$ The order of $\mathbb{Z}_{N^2}^*$ is $N\phi(N)$. Maybe there is sth with the crt and the isomorphism $\phi: \mathbb{Z}_{N^2}^* \mapsto \mathbb{Z}_{p^2}^* \times \mathbb{Z}_{q^2}^*$ but $\mathbb{Z}_{p^2}^*$ and $\mathbb{Z}_{q^2}^*$ are not defined modulo a prime
Mar
18
comment Are there hash algorithms with variable length output?
@D.W. But is this secure?In the sense that there are only 360 possible values that can be brute forced easily
Mar
18
comment Are there hash algorithms with variable length output?
So what if i want a hash output that would range from $[0,360]$?If it was an integer then this is totally insecure as we need roughly 9bits. But can we extend the output from 9 bits to 160 by assuming that the integer part would always be 9 bits and then the other 151bits would be used for precision? And i do not care of hashing the same input to the same output.So it resembles that i am in need of a variable out pseudorandom generator
Feb
22
comment Can I safely replace XOR with ADD in a stream cipher?
So the only objective for the choice of the bitwise operation in a stream cipher is efficieny?Could we use birwise AND/OR as well?
Feb
11
comment Proofs by reduction and times of adversaries
There is a tighter reduction for RSA-FDH here: iacr.org/archive/crypto2000/18800229/18800229.pdf
Jan
30
comment Which blind signature schemes exist, and how do they compare?
I admire you for you patient to write so long analytical answers most of the time
Jan
30
comment Proofs of security methodologies
@mikeazo I don't agree very much with the categorization as the sequence of games are part of a more general category which is the indistinguishability game played between the attacker and the simulator-oracle (IND-CPA,IND-CCA,IND-CCA,)
Jan
21
comment What does it mean that $BW_N$ is a permutation over the squares mod N?
Suppose that you have a set of numbers $S$ in a specific order.Then randomly rearranging the elements means that you permute the elements.Now in a trapdoor permutation you have a key. Once you know the key you can reinverse the set in its original form.Suppose i.e that i permute by shifting one element at my right.This is the key.Now in your case the trapdoor of the permutation is the integer factorization problem.
Jan
18
comment How to ensure that a “received value” is not altered?
MAC considers a symmetric setting in which two clients have agreed on a secret key
Jan
16
comment Where can I find source code for ideal world simulation?
People from theoritical cryptography would commit suicide if they ever discover code for simulation based security
Jan
15
comment How to understand the Bilinear mapping with an example
You don't need to prove. You need to evaluate its correctness, i guess
Jan
10
comment How to prove that a ciphertext is encrypting multiplication of two values?
What do you mean by generic proof argument? How i can convince that the non-DLP encrypted value lies in predefined range?I just make a huge assumption that the encrypted values is the witness for a proof that is submitted independent from the ciphertext?
Jan
6
comment Open source implementations of Symmetric Searchable Encryption and Order Preserving Encryption
We are waiting for the link :)
Dec
26
comment How to prove that a ciphertext is encrypting multiplication of two values?
Yes but what if you don't want to use DLP based public key encryption schemes?
Dec
24
comment Difference between computational and statistical indistinguishabilities
Also statistical indistinguishability is stronger than computational indistinguishability as there is not restriction on the computational power. So it might be the case that a scheme preserves computational indistinguishability but not the statistical indistinguishability
Dec
19
comment Are those two distributions indistinguishable?
$f(x)$ is defined $mod N^2$ as well
Dec
19
comment Are those two distributions indistinguishable?
I don't understand your comment. you are given 1 number. Either in the first form or in the other form and you have to decide whether or not there exist a quadratic residue for this number.
Dec
17
comment How does OAEP improve the security of RSA?
How the legal receiver gets rid of the pad if he doesn't know the $r$? It just spits the $#pad$ bytes? That implied a public knowledge of the pad length.
Dec
16
comment Advantages of bilinear map
Maybe i should rephrase: "The first use of pairing that we know is not for construction of cryptographic primitives but to break some hard assumptions as the DL in specific groups"
Dec
7
comment How do I calculate the private key in RSA?
These are standard techniques you can find in all books.We say the same thing.In order to compute the inverse you can use the extended euclidean algorithm