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Jul
23
answered Different padding rules for Merkle–Damgård and Keccak/sponge function
Jul
23
answered Textbook RSA with exponent e=3
Jul
23
reviewed No Action Needed Which algorithm do you recommend for practical use to generate unique passwords for each website?
Jul
23
comment How is this affine function a pair wise independent permutation?
@sashank: no; the probability that $f(A)=C$ is $1/2^n$; $f(B)$ is independent of $f(A)$ except we know that $f(B)\ne f(A)$, hence given the first holds, there are $2^n-1$ possible values that $f(B)$ can take on. It is equidistributed other than that, and hence joint probability that $f(A)=C$ and $f(B)=D$ is $1/2^n \times 1/(2^n-1) = (2^{2n}-2^n)^{-1}$
Jul
22
comment RSA with modulus n=p²q
Like ECIES; decryption is a lot faster than RSA; for encryption, you can do precomputation so you can do most of the work before you see the message.
Jul
22
answered RSA with modulus n=p²q
Jul
22
comment RSA with modulus n=p²q
@CGFoX: however, wouldn't that slow down the operation? What would the advantage be over doing standard RSA, and picking larger primes?
Jul
22
comment MAC using a modified CBC mode of operation
@fgrieu: why don't you convert your comment into an answer? That way, it can be upvoted and accepted.
Jul
22
reviewed No Action Needed Is my implementation of a PRG at least intuitively secure?
Jul
21
reviewed Close Best Asymmetric Encryption Standard for Communications?
Jul
21
comment Choice of multiplication polynomial in Rijndael s-box affine mapping
Do you have any evidence that these metrics have anything to do with the security of AES? Are there any theoretical (reduced round) attacks known against AES that would be foiled by an sbox that is better by these metrics?
Jul
21
reviewed Close How do the following new (2013) ECC curves compare in security or efficiency?
Jul
20
revised AES-CTR-256 Sub Keys With Encrypted Sub Key Index
Fixed grammar
Jul
20
comment Security equivalent to Diffie–Hellman problem?
@RickyDemer: generally, we do Diffie-Hellman in groups of known order; if you are doing it in the RSA group, an alternative way to compute $g^{b^{-1}}$ is to do a DH with $g^b$ as the base $h$, and the two public values $h^x=h^y=g$; the Oracle will return the value $h^{xy} = g^{b^{-1}}$. As for the other direction where $b$ might not be invertable (and so $b^{-1}$ doesn't exist), we can replace $b$ with $b+i$ for known $i$; with nontrivial probability, we can find an $i$ where inverse exists; given $g^{a(b+i)}$, it's easy to recover $g^{ab}$
Jul
20
answered Security equivalent to Diffie–Hellman problem?
Jul
20
comment Turning PRPs in PRGs with a counter
@Sklivvz: when was the last time you generated 1 TiB of output from a random number generator? In any case, if you need to generate more, all you need to do is periodically rekey the block cipher.
Jul
20
answered Turning PRPs in PRGs with a counter
Jul
19
reviewed Leave Closed Attacks on Full TripleDES
Jul
19
reviewed Close LFSR and Markov chain question
Jul
19
reviewed Looks OK Can a EC private key be derived from a public key?