10,054 reputation
12451
bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 3 years, 4 months
seen 9 hours ago

Dec
10
comment Encryption Key derivation from numeric PIN?
if n>20 it should be fine
Dec
10
comment Is it possible to modify SSL handshakes to enable PFS while still using RSA during the handshake?
1) If you invent your own ciphersuite, you could use ephemeral RSA. But creating a new RSA key is much more expensive than generating a DH key. So you might want to reuse it across connections and only rotate every minute. 2) You could use the plain RSA suite to achieve a limited form of forward secrecy if you frequently obtain a new certificate. Might be expensive depending on the CA.
Dec
9
comment Would this prevent FNV1a 32 bit hash collision?
What goal do you want to achieve? Your character wise hashing is no better than ROT13 encryption.
Dec
8
comment Assuming that we had a way of finding primes, could RSA be used without computers?
Why RSA? Using DH over a pregenerated elliptic curve or a pregenerated finite field should be faster and doesn't require per-key primes.
Dec
8
comment Assuming that we had a way of finding primes, could RSA be used without computers?
Exponentiation without computers is still pretty annoying
Dec
7
comment why RSA uses Semiprime numbers?
Factoring a big number which has less than two big factors is much easier.
Dec
6
comment Why are these techniques not feasible to crack RSA?
Your last sentence isn't just misleading, it's plain wrong. Calculating $\phi(n)$ and factoring $n$ are equivalent. The RSA problem is about solving $c=m^e \pmod n$ for $m$. While best known way is to factor $n$ and compute $\phi(n)$, it might be possible to solve this equation without learning $\phi(n)$
Dec
6
comment Can insecure algorithms be combined to form a secure algorithm?
But they aim at pseudo-randomness, not collision resistance and they xor the hashes instead of concatenating them.
Dec
6
comment Why are these techniques not feasible to crack RSA?
@AliGajani If you know $\phi(n)$,your technique works. In fact it's how $d$ is computed during RSA key generation. But an attacker does not know $\phi(n)$, so they can't use this technique.
Dec
6
revised Why are these techniques not feasible to crack RSA?
deleted 8 characters in body
Dec
6
reviewed Approve suggested edit on Why are these techniques not feasible to crack RSA?
Dec
5
comment counting points not on elliptic curve
Your notation is confusing since you use $a,b$ as curve parameters and as the coordinates of a point.
Dec
5
comment Can cryptocurrency mining devices be used for cryptanalysis?
@HenrickHellström Password hashing with different password guesses is parallel as well. If you had fixed SHA-256 cores and flexible logic between the calls, that could be used for both hashing and mining. But I doubt miners contains those flexible parts required to repurpose them to crack PBKDF2.
Dec
4
reviewed Approve suggested edit on Are there any bijective one-way functions not based on number-theoretic hardness assumptions?
Dec
4
revised Who uses Dual_EC_DRBG?
added 52 characters in body
Dec
4
comment The real-life meaning of proving over a group that doesn't support the oracle?
An oracle gives an advantage to the attacker. So absence of the oracle shouldn't hurt security. (Though for some schemes, absence of the oracle means that the legitimate user can't be implemented efficiently. For example BLS requires uses cheap DDH to validate the signature.)
Dec
4
comment How can I use SSL/TLS with Perfect Forward Secrecy?
NIST curves are a bit suspicious since they contain large constants chosen without proper application of nothing-up-my-sleeve techniques. But we don't have any idea how such a weakness would work.
Dec
3
comment RSA performance
@Ajit If you were to somehow encrypt a long message with RSA, the performance would decrease linearly with the length of the message. Since RSA is pretty expensive, that'd be rather slow (perhaps 100kB/s). But almost nobody does that (use hybrid encryption instead), and the common RSA standards don't specify how to do so.
Dec
3
comment Why can an RSA signature be authenticated ONLY with the signer's public key?
It doesn't come down to probability if the match is deliberate. For example to claim "I wrote this message, there is my signature on it".
Dec
3
comment Why doesn't this dummy mutual authentication protocol provide mutual authentication?
Another problem is that Bob who received a (R, [R+1]A) pair from Alice, can use that pair to impersonate Alice to any third party.