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Apr
9
answered AES-256 Shift-Rows Offsets
Apr
9
revised What is h in the improved solution of RSA algorithm?
added 106 characters in body
Apr
9
revised What is h in the improved solution of RSA algorithm?
Added mention to a reference they apparently didn't read
Apr
9
answered What is h in the improved solution of RSA algorithm?
Apr
9
answered Secret Sharing 1 Required
Apr
9
comment Secret Sharing 1 Required
Is this homework?
Apr
8
comment What's wrong with this “order-preserving MAC” function?
You asked about a order preserving Message Authentication Code, MACs are assumed to be secure even in chosen text environments; a secret step size would easily be reconstructed if the attacker got one or two valid text/MAC pairs. And, even if the attacker didn't have any valid text/MAC pairs, we can estimate the size of a secret stepsize, by examining the MACs he does have; if they are all restricted to a small region, stepsize is likely tiny; if they span almost the entire range, stepsize must be large.
Apr
8
answered What's wrong with this “order-preserving MAC” function?
Apr
8
comment What's wrong with this “order-preserving MAC” function?
From what I see from the pseudocode, it would appear that $OPF(n)/stepsize - n \in \{0,1\}$. If so, it would appear that the function fails in its goal of "the adversary must not be able to guess the location of the points".
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
@RickyDemer: with FHE, we have the additional operation of taking any value, and encrypting it with the public key. Hence, we can take the value 1 and encrypt it; that encrypted value can be used just like any other encrypted value. When you add possible constant '1' values, XOR and AND are indeed universal.
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
@D.W. I suspect that you're getting the direction of the argument wrong. sashank is not arguing that addition and multiplication can be built out of universal gates; he's trying to argue that XOR and AND (which are jointly universal) can be built out of addition and multiplication; I just mentioned that the straight-forward way of creating XOR and AND doesn't quite work, and I showed a valid method of creating a universal gate.
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
@D.W.: in my opinion, the answer needed to be sketched out in greater detail. If sashank didn't mean "addition == XOR" and instead he meant that + and $\times$ can be considered to be made up of XOR and AND gates, and we can use the embedded gates in a universal way, well, that doesn't obviously follow, After all, + and - can also be considered combinations of XOR and AND gates, however that pair is not a universal set, hence we cannot use the embedded gates from those two operators in a universal way.
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
While the conclusions are correct, it turns out that the details are a bit more complicated than "ADD==XOR". The problem is that if we want to limit are internal data to the values $(0,1)$, the simple computation $A+B$ may result a result 2 which is outside of that. One way to obtain an universal gate is to compute the NAND function by encrypting the values $1$ and $-1$, and computing $NAND(A,B) = 1 + (-1 \times A \times B)$, where $+$ and $\times$ are the FHE operations.
Apr
6
awarded  Necromancer
Apr
5
comment Adequate DH secret size
Also, as for the size used by TLS, the TLS protocol does not specify the size of the DH private value. Obviously, various a TLS implementation must use a specific size, however different implementations would use different sizes.
Apr
5
comment Definition of a Statistical Test
An extremely low false positive rate; when I attempt to estimate the probability of a false positive of a truly random long string, I get something on the order of $10^{-88}$
Apr
4
answered HMAC-SHA1 vs HMAC-SHA256
Apr
3
comment TLS Key Block calculation - What is a PRF?
@Eddie: you are correct, except that PRFs in general do not produce arbitrary long outputs; that is a special property of the PRF that TLS uses
Apr
2
answered TLS Key Block calculation - What is a PRF?
Apr
2
comment What is h in the improved solution of RSA algorithm?
Well, given a public key $(N,e)$ and plaintext/ciphertext pairs $(P,C)$, an attacker can replace it with an RSA key $(N,e)$ and plaintext/ciphertext pairs $(P,eC)$; any attack on this system would immediately imply an attack on the RSA system. We believe the RSA system to be secure (because, while $e$ was chosen so that $e^{-1}$ is small, there's no known weakness there), and hence this system is secure.