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reviewed No Action Needed Which algorithm do you recommend for practical use to generate unique passwords for each website?
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 $1/2^n \times 1/(2^n-1) = (2^{2n}-2^n)^{-1}$
reviewed Close How can I solve this modular equation?
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.
answered RSA with modulus n=p²q
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?
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.
reviewed No Action Needed Is my implementation of a PRG at least intuitively secure?
comment AES CTR rekeys rapidly, does this produce patterns?
The submitter really is asking us to review his pet cryptography project -- that's not what this site is about.
reviewed Close Best Asymmetric Encryption Standard for Communications?
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?
reviewed Close Which of following new (2013) ECC curves is the most secure or efficient?
reviewed Close How does the Hashlet work?
revised AES-CTR-256 Sub Keys With Encrypted Sub Key Index
Fixed grammar
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 $g^{ab}$
answered Security equivalent to Diffie–Hellman problem?
reviewed Close Cryptolocker 2.0 ransomed #1.23 btc
reviewed Close Video encryption at server, decryption on mobile using AES
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.
answered Turning PRPs in PRGs with a counter