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Jun
7
answered Why are there only positive value points on an elliptic curve?
Jun
6
comment What are differences between $E(F_p)$ and $E(Z_p)$?
The difference comes if you do ECC in an extension field; where the field size is $p^k$ for $k>1$. In that case, $Z_{p^k}$ would imply that you're doing your math modulo $p^k$, which would be incorrect (that's not a field). Instead, in that case $E(F_{p^k})$ would be the correct notation. Of course, nowadays we usually stick to prime fields; in that case both notations are equivalent.
Jun
5
revised Pick faster private exponent
deleted 1 character in body
Jun
5
answered Pick faster private exponent
Jun
5
comment How (in)secure is a signature based on DSA with DSS1 (SHA1) in reality?
@RichieFrame: collision resistance comes into play only if the attacker gets to pick the valid signed text and the forgery. CodeX said we was doing a license file; if he is the only one that generates the valid license files, and do not allow anyone else to "suggest" things, he need not care about collisions -- instead, he needs to worry about "second preimage" attacks. And, SHA-1 appears to be strong against that attack model.
Jun
5
revised Use of Different keys with PCBC
Extended explination
Jun
5
answered Use of Different keys with PCBC
Jun
5
reviewed Leave Open Use of Different keys with PCBC
Jun
4
reviewed Approve Is there an oblivious decryption scheme?
Jun
4
answered Is there an oblivious decryption scheme?
Jun
3
comment Montgomery Ladder vs Double-and-Add
@CodesInChaos: the point of these algorithms is that they try to resist cache-based side channel attacks; that's hard to do with a look-up based algorithm. Yes, if you don't care about those side channel attacks (either you know no one else is sharing your cache, or you're doing ECDSA signature verify), there are considerably more efficient alternative available.
Jun
3
revised Montgomery Ladder vs Double-and-Add
added 112 characters in body
Jun
3
answered Montgomery Ladder vs Double-and-Add
Jun
3
reviewed Close Theory for pre-paid debit card: card-to-card transfer
Jun
2
comment Precomputation attacks on RSA
@RickyDemer: that part is true; however if the hash function is chosen properly, it is still harder than factoring the modulus (albeit not to such an extreme extent)
Jun
2
comment Precomputation attacks on RSA
@RickyDemer: how does this precomputation attack work against RSA used properly, that is, with a collision resistant hash function?
Jun
2
comment Measure ECC key size
Yes, it would be 160 bits. Note that a 160 bit elliptic curve can be broken with approximately $2^{80}$ operations.
Jun
2
answered Precomputation attacks on RSA
Jun
2
comment Is RSA key size the size of private key exponent in public key encryption?
@user2934766: since $n = p \times q$, then increasing $p$ and $q$ will, of course, increase $n$. To pick an $n$ of 15360 bits, you need to select primes $p$ and $q$ of 7680 bits. That said, if you think you need a public key system that difficult to solve, you probably should look at an Elliptic Curve system
Jun
1
answered Parallel hash construction