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Jan
30
revised Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$
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Jan
30
revised Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$
added 418 characters in body
Jan
29
revised Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$
added 136 characters in body
Jan
29
revised Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$
added 350 characters in body
Jan
28
comment Secret sharing - no dealer, modifiable, verifiable
If robustness isn't a requirement, also look at Pedersen's original scheme link.springer.com/chapter/10.1007%2F3-540-46416-6_47
Jan
28
comment Secret sharing - no dealer, modifiable, verifiable
This sounds a lot like the Joint-Uncond-Secure-RSS scheme of link.springer.com/chapter/10.1007%2F3-540-68339-9_31. The trick is to let each participant be a dealer, or, put differently, build the scheme around participants who generate their shares randomly.
Jan
28
asked Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$
Jan
27
comment How can I find the prime numbers used in RSA?
The approach is just basic algebra. If the factors are close to the floor $x$ of the square root, the equation $r + (x-p)(q-x) - x(q+p-2x)$ will be dominated by the first and third term and the second factor of the third term will consequently be a function of the magnitude of $r$.
Jan
27
comment How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?
AES is believed to be (IND-CPA) secure even if the plain text is chosen by the attacker, so why do you include the restriction of no operator errors?
Jan
26
answered What does $\Pi$ represents in cryptography?
Jan
26
revised What does $\Pi$ represents in cryptography?
formatting
Jan
25
revised How can I find the prime numbers used in RSA?
added 439 characters in body
Jan
25
answered How can I find the prime numbers used in RSA?
Jan
14
comment Do I need to prepare plain text before encryption?
I see no obvious harm in anyone following your recommendation, but it is completely pointless as far as cryptographic security goes.
Jan
13
comment Do I need to prepare plain text before encryption?
Compression does not increase the total entropy of the plain text, but it does increase the average entropy per bit, by, well, compressing it. Theoretically, it might increase security in some sense, but only in so far that the compression algorithm effectively hides the length of the original plain text.
Jan
6
comment Shared secret: Generating Random Permutation
To avoid unnecessary confusion: I noted in my comment that a threshold scheme would introduce a risk of collusion and didn't "propose" such a scheme, but only stated a problem.
Jan
6
comment Shared secret: Generating Random Permutation
How are you going to enforce such a requirement? Suppose Alice, Bob and Carol are playing. Alice has already folded but remain online. Bob has gone all-in but realizes he is about to loose just before the last card is to be revealed. Bob privately asks Alice to pull the plug. Alice pulls the plug.
Jan
6
comment Shared secret: Generating Random Permutation
Please note that any mental poker protocol would leave you with a problem of how to fold, if there are more than two players. If all players have to be present to decrypt the next card, one player might simply go offline and make it impossible for the remaining players to complete the game. If you solve that by using threshold secret sharing, you introduce a possibility of collusion.
Dec
31
reviewed Approve suggested edit on Why nobody considers counter re-keying as a standard Block Cipher Mode?
Dec
30
answered Where is my private key stored when I communicate to a website that uses SSL/TLS?