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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 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 this RSA variant?
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.
Apr
1
comment What is h in this RSA variant?
Actually, these authors just copied the 2KGEA algorithm from their reference [3]: iasir.net/IJSWSpapers/IJSWS13-272.pdf - however, that paper doesn't answer any of the above questions.
Apr
1
revised What is h in this RSA variant?
deleted 5 characters in body
Apr
1
answered What is h in this RSA variant?
Apr
1
comment Demonstrating Diffie-Hellman key exchange using only p, A, B;
There are 50976 generators for $Z/104933$, and that's assuming that, by generator, the question meant a generator for the entire group, and not the generator for the subgroup we'll be doing DH in. So, 5 is a generator; how do we know that that's the generator that's meant, and not any of the 50975 other generators that exist?
Apr
1
comment Demonstrating Diffie-Hellman key exchange using only p, A, B;
No, there is not enough information given to let you derive $g$. Now, if they said "use the smallest value that generates the group for $g$", then you could find that, and then use that. However, remember that any value of $g$ will work within the protocol (although some choices, such as $g=1$, do have some security issues, of course, in this toy example, there aren't any secure choices). Also, in practice, we generally don't use values of $g$ which generate the entire group, and so you are told to use such a value, that's something contrary to common practice.
Apr
1
comment Demonstrating Diffie-Hellman key exchange using only p, A, B;
I believe you'll also need the value of $g$; you cannot derive it with the information you have
Mar
31
comment Can a commutative block cipher be indistinguishable from a random permutation, for fixed key?
@fgrieu: actually, it sounds like what you really ask about are known plaintext attacks; given a random set of $(x, P(x))$ pairs, can we distinguish a random $P$ from $E(k)$? Given the Pohlig-Hellman cipher, we can distinguish it in this model; is that a fundamental property of all commutative ciphers, or is that just a side effect of how Pohlig-Hellman achieves commutativity and another commutative cipher might be secure in this model?
Mar
31
answered Can a commutative block cipher be indistinguishable from a random permutation, for fixed key?
Mar
29
awarded  rsa
Mar
27
answered Is it secure to choose d in a RSA key pair?
Mar
26
comment m ∈ Zn \Z*n, RSA works but not secure
You still have the wrong value for $\phi(p)$. $\phi(p)$ is defined to be the number of values between 1 and $p-1$ which is relatively prime to $p$. If $p$ is prime, how many of the values between 1 and $p-1$ are relatively prime to $p$?
Mar
26
reviewed Approve suggested edit on Encryption of numeric value using playfair