All Questions
0
votes
2answers
66 views
Proper Way to Encrypt Data with Two Keys?
I'm going to develop a system that will have two keys. One supplied and generated by the system that's specific to an individual user and one from the user.
I plan on using AES.
Does it make sense ...
-1
votes
2answers
120 views
Computational indistinguishability and example of non polynomial algorithm
The wikipedia page on computational indistinguishability says that two ensembles are not distinguishable if "any non-uniform probabilistic polynomial time algorithm A" cannot tell them apart. To help ...
-1
votes
2answers
166 views
Cryptographic Symmetric Stream Cipher
Let me know a cryptographic symmetric stream cipher system with only two functions say S() and P() and it should satisfy the following conditions:
There will be two independent computers say M1 and ...
1
vote
1answer
28 views
How does the birthday attack work in AUTH and UF-CMA games?
In the AUTH and UF-CMA games, an adversary is required to forge a ciphertext or message/tag pair to win the game. Given an encryption scheme $E$ and a PRF $F$, let $\hat{E} = C || F_k(C)$ and $C = ...
1
vote
1answer
111 views
How to calculate y value from ((y*y) mod prime) efficiently
i am working ECC-224 bit. can any one tell me, how to calculate y value from ((y*y) mod prime) efficiently for large bit numbers.
0
votes
1answer
58 views
Does SRP reduce to DH key echange when shared password is not secret?
I can find JavaScript implementations of SRP (Secure Remote Password protocol), but nothing that inspires confidence for Diffie-Hellmen key exchange. I also have a separate need for SRP later.
I ...
0
votes
1answer
55 views
How to make a message into a polynomial on NTRU encryption?
How to make a message into a polynomial on NTRU encryption? for example how we can conver 'hello world' to polynomial...
i have read the converting operation on IEEE Std 1363.1- 2008, but i can't ...
0
votes
1answer
143 views
Anonymity in end to end encryption
Considering a scenario of anonymous data transfer between seller and buyer using proxies. If we consider that there are three proxies that are being selected by buyer to obtain data from different ...
0
votes
1answer
117 views
Why is proof-by-reduction needed (for Elgamal proof of security, for example)?
The textbook proof for Elgamal encryption basically reduces to the Decisional Diffie-Hellman assumption (DDH).
Elgamal:
$Gen(.): x \xleftarrow{R} \mathbb{Z}_p$; $Enc(m,g^x): r \xleftarrow{R} ...
-1
votes
1answer
39 views
Sematically Secure McEliece
I am read the Lemma 2 (pp13) in the paper [1]. Here a make a question Why "for any $Hash_z$ and any $Gen$"? The author of paper reply
The reason why "for any $Hash_z$ and any $Gen$" is that if ...
-1
votes
1answer
103 views
Chosen Plaintext Attacks
Assuming the ability to launch Chosen Plaintext Attacks (CPA), how many oracle calls an attacker
needs to break the affine cipher? and how
-1
votes
1answer
123 views
Fiat-Shamir signature
I have a question about Fiat-Shamir signature:
A hash function is h(w)=w mod 2011 and w1=2623, w2=3269, w3=1938.
What is h=? and how to determine k.t bits?
-2
votes
1answer
145 views
How does one find out ciphers/passwords without knowing what cryptographic algorithms are used?
If one does not reveal what cryptographic algorithms are used, how does a cracker find out a password/cipher that is used to communicate data? I heard that because there are methods to try cracking ...
-4
votes
1answer
101 views
Indistinguishability CPA and CCA2
I am study security notions in two lecture and I am cofusing with the concepts IND-CCA and IND-CPA2. About IND-CCA in wikipedia say
Indistinguishability under chosen ciphertext attack/adaptive chosen
...
