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May
28
revised how much trust can we place in protocol verifiers?
Linking to relevant sources is good, but they must be sensible sources.
Apr
24
comment Generalize the Merkle-Damgard construction for any compression function
Let $m = m_1 m_2 \dots m_n$. Suppose $y_0$ is fixed and let $y_i = f(y_{i-1}, m_i)$, $h(m) = y_n$. This is the basic Merkle-Damgård construction, but some extra tricks are needed. You first need to understand why these tricks are needed. Study how you recover a collision for $f(\cdot)$ from a collision in $h(\cdot)$. Then come up with a suitable trick. Hint: expansion.
Apr
20
comment Diffusion in Shamir's secret sharing scheme
Based on your description, it serves no purpose.
Apr
11
comment Is there a simple zero knowledge proof of $x$ for $b=x^x\pmod p$?
If you allow $x>p-1$ it is easy. Can you do it with $0 < x < p-1$?
Mar
27
comment Security proof of FO(Fujisaki-Okamoto) hybrid encryption
Note that this only works because the decryption algorithm recreates $C_1$ after recovering $\sigma$. Modern schemes do without recreating $C_1$.
Mar
19
comment How do the following new (2013) ECC curves compare in security or efficiency?
arxiv.org/abs/quant-ph/0301141
Mar
19
comment How do the following new (2013) ECC curves compare in security or efficiency?
Quantum computers can compute d.logs. on all of these curves. "Post-quantum" they have no security.
Mar
19
comment Subexponential algorithms for DLP in $\mathbb{Z}_s \times \mathbb{Z}_t$
This is reasonably correct. One quibble: Can $h_1g_1^{-1}$ and $h_2 g_2^{-1}$ be different?
Mar
18
answered Subexponential algorithms for DLP in $\mathbb{Z}_s \times \mathbb{Z}_t$
Mar
18
comment How do the following new (2013) ECC curves compare in security or efficiency?
"post-quantum"?
Mar
16
answered Should different key pairs be used for signing and encryption?
Mar
16
comment Elliptic Curves of different forms
The emphasis placed on "easy" is justified. People have an amazing ability to screw things up. Making it easier not to screw up is worthwhile. This is why we now have AEAD schemes instead of just encryption+MAC, etc., etc.
Mar
16
comment Elliptic Curves of different forms
Both. Modern curves are easier to implement correctly, and implementations are faster. No, I have no idea about implementations. Dan Bernstein probably has something sensible, but it may not be suitable for you.
Mar
16
comment How can I create an RSA modulus for which no one knows the factors?
A good place to start may be: Carmit Hazay, Gert Læssøe Mikkelsen, Tal Rabin, Tomas Toft: Efficient RSA Key Generation and Threshold Paillier in the Two-Party Setting. CT-RSA 2012: 313-331.
Mar
16
answered Elliptic Curves of different forms
Mar
6
answered Secure Broadcast Channel
Mar
5
comment Long-term data protection, storage of old encrypted traffic and quantum cryptocalipse
Quantum computers suitable for running Shor's algorithm are still stuck at six qubits or so. Post-quantum cryptography is certainly interesting as a research topic, but compared to all the real threats you face today you should give it low priority.
Mar
4
comment GCM vs CTR+HMAC tradeoffs
Polynomial evaluation can be computed in parallel.
Mar
4
answered Is it possible to calculate the 'skeleton key' for DUAL_EC_DRBG? What would it take?
Mar
3
answered Is it meaningful to consider the leakage of master key of KGC?