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Dec
3
comment Sorting over encrypted data with different symmetric keys
it seems that you need to put a bit of trust to some third party in order the latter to transform ciphertexts coming from different users to ciphers seem to be encrypted by a single user. Look at proxy re-encryption techniques
Nov
28
comment Bilinear map assumpion
Ok, i said DL is the strongest in the sense that breaking DL you break CDH and then DDH
Nov
26
comment Bilinear map assumpion
You were right about the other type of forgery by exponentiation. What about now? Assiming k is secret
Nov
26
comment Bilinear map assumpion
I thought DL is the strongest assumption. XDH assumes DDH is hard in G1 for asymmetric pairings
Nov
15
comment what problem happen if we always use IV Zero in CBC Mode?
Do not forget to mark the post as a valid answer
Nov
15
comment what problem happen if we always use IV Zero in CBC Mode?
If $0$ comes as a result of a random generation then it is fine, but every time it should change
Nov
15
comment what problem happen if we always use IV Zero in CBC Mode?
The property that we need for the IV is to be a random number , that changes per encryption
Nov
10
comment Difference between collision resistance and target collision resistance
@archie. In 2PIR the adversary is also trying to find a collision for a fixed message. I do not understand the difference with TCR. You are explaining it as TCR is 2PIR and 2PIR ("compared to the more general notion of Second Preimage Resistance, where the adversary to find a second preimage for a randomly chosen message") is collision resistance
Sep
25
comment What are the differences between proofs based on simulation and proofs based on games?
Thank you. But, in sb proofs there is a pre-agreed leakage in the ideal evironment. From my point of view and maybe i am wrong the question is and what is missing from sb proofs: How this leakage does not affect the security definition. And i am saying that because in the sb proofs that i have seen the point of interest is to show that the two worlds behave equivalently and not how the leakage affects the scheme. So it seems on me that this is the negative part with sb proofs. And as you correctly pointed out with game based there is no connection from IND-CPA to semantic security
Sep
17
comment Zero knowledge proof of bilinear equation
The prover has $e(a,b)e(g^{c_i},b)$ which has been forwarded by a honest user. The prover does not know $g^{c_i},b$
Sep
17
comment Zero knowledge proof of bilinear equation
I edited the question. Actually there are multiple of these equations. A honest user has computed $p=e(a,b)e(g^{c_i},b)$, a prover computes $p^r$ and a verifier wants to be convinced that $p^r = [e(a,b)e(g^{c_i},b)]^r$ without knowing $b,g^{c_i}$. It actually knows $\sum{g^{c_i}}$
Sep
17
comment Zero knowledge proof of bilinear equation
It has $\prod{e(a,b)^r}\prod{e(g^{c_i},b)^r}$
Sep
17
comment Zero knowledge proof of bilinear equation
It has a valid correct $r$. Both they do have it. It is not clear at me what encpsulation is?
Sep
1
comment What are the roles of the simulator in simulation based proofs
Does not seem as cheating in the proof when the simulator is interacting with the real world adversary in order to output indistinguishable outputs?Since in the proof it is desirable to show that the two parties (real world adversary-ideal simulator) learn equal information.
Jul
30
comment What consequences do the plaintext space size has on the performances in the BGV scheme?
I think it is not clear in your mind. Ciphertext size depends on the size on the group and its bitstring representation which depends on $p$ obviously. What is your question about?size of p=1024bit which is the ciphertext space then |ciphertext|=1024 bits. Since you want additions why you need BGV, and not Paillier?
Jul
30
comment What consequences do the plaintext space size has on the performances in the BGV scheme?
You have to be more precise with respect to what operations you need to perform. For instance for multiplication there are various techniques:Karatsuba, Montgomery. Here you can find an idea : en.wikipedia.org/wiki/…
Jul
30
comment What consequences do the plaintext space size has on the performances in the BGV scheme?
The bigger the modulo the more computationally expensive the modular operations. This is obvious.
Jul
28
comment Reduction to cdp,dl or cdh?
@D.W. It is the value to be encoded. and it comes from $\mathbb{Z}_p^*$
Jul
27
comment Reduction to cdp,dl or cdh?
I want to be deterministic. This leakage is acceptable
Jul
24
comment Differential Privacy and appropriate noise distribution
yes but why laplacian and not gaussian for example??What is the special property that makes laplacian suitable for differential privacy