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1500 questions
13
votes
3 answers
How are points on an elliptic curve discretized?
I'm a working programmer (read: a person without a maths degree) trying to get a better grasp on elliptic curves specifically in the context of elliptic curve cryptography (though to be clear, this is for personal development — I'm in no way trying…
QuartzCrystal
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13
votes
1 answer
Safely sorting secret data
Suppose you have a secret list of n distinct integers. How would you sort this list in a way that is not vulnerable to timing attacks? I tried looking up "constant time sorting" and other related queries but that expectedly lead nowhere.
Kai Arakawa
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13
votes
7 answers
Can I encrypt a message by swapping bits in the text?
I have tried out an encryption method, in which I swap bits in the text.
The text length is N bit, then I generate several random number pairs in the range 0..N-1, as [n,k] pairs. After that, I swap the n-th and k-th bits in the message, if they are…
Konstantin
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13
votes
0 answers
RSA key such that pi deciphers to your name per RSA-OAEP
Can you efficiently construct an RSA public/private key pair with $8k$-bit public modulus such that $C=\left\lfloor\pi\,2^{8k-2}\right\rfloor$ deciphers per RSA-OAEP to your name as a bytestring in ASCII or UTF-8?
The decryption must be per…
fgrieu
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13
votes
2 answers
Can a computationally unbounded adversary break any public-key encryption scheme?
Assume there is a public-key encryption scheme $(KeyGen, Enc, Dec)$ with perfect correctness (i.e., for all messages M and valid key-pairs (PK,SK), we have $Dec_{SK}(Enc_{PK}(M))=M$).
Will there always be a function $A$ such that for all messages M…
huyichen
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13
votes
4 answers
Why are good passwords required if we use good hashing algorithms?
Again and again are we adviced to make good passwords: At least 12 chars, numbers, signs, upper and lowercase.
But why is that really needed?
I can see the need, if the system uses a hashing algorithm that can be implemented in ASIC, where an…
Ole Tange
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13
votes
0 answers
How Significant is the New Quasi-Polynomial-Time Attack on Fixed Characteristic Discrete Logarithms?
There is a new paper by Kleinjung and Wesolowski on eprint that claims and proves a new attack on the discrete logarithm problem in finite fixed characteristic fields in quasi-polynomial time.
Concretely a run-time of $$(pn)^{2\log_2n+O(1)}$$ is…
SEJPM
- 45,967
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13
votes
0 answers
RSA factorization with special primes
Suppose that primes for RSA modulus are generated using formula:
$P_i(x,y) = \operatorname{next\_prime}(x^{z_i}+y^{z_i}) = x^{z_i}+y^{z_i}+d_i$
where $x,y$ are unknown random numbers with size 128 bits
$z_i$ - are known small integers exponents,…
Kamil Pliszka
- 131
- 4
13
votes
2 answers
SHAKE-128/256 or SHA3-256/512
Would it be better to use SHAKE-128/256 or SHA3-256/512? In what situation should I chose one over the other?
Alejandro Martinez
- 141
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13
votes
3 answers
What is Identity-Based Encryption (IBE) and why is it "better"?
Most CS/Math undergrads run into the well-known RSA cryptosystem at some point. But about 10 years ago Boneh and Franklin introduced a practical Identity-Based Encryption system (IBE) that has excited much of the research community and produced a…
Fixee
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13
votes
3 answers
Why was the term "discrete" used in discrete logarithm?
Is there anything especially "discrete" about a discrete logarithm? This is not a question of what is a discrete logarithm or why the discrete logarithm problem is an "intractable problem" given certain circumstances. I'm just trying to determine if…
JohnGalt
- 546
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13
votes
2 answers
Does secp256k1 have any known weaknesses?
I am wondering whether there are any properties of the curve which would technically make it easier to attack than any other curves of 256 bits in size.
I have heard that being a Koblitz curve, it has a few bits weaker security than some other…
Matt
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13
votes
1 answer
How would one crack a weak but unknown encryption protocol?
I asked a question on security.stackexchange, but was told it would be a better fit here:
https://security.stackexchange.com/questions/32779/how-would-one-crack-a-weak-but-unknown-encryption-protocol
My question is: Assume I'm an attacker trying to…
Ram Rachum
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13
votes
2 answers
What motivated the creation of RSA and ECDH?
Recently I've been learning about cryptography and so far I am loving it. However, there are some things I do not comprehend.
As far as I know, RSA was published in 1979 while New Directions on Cryptography by Diffie and Hellman was published in…
a-lawliet
- 151
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13
votes
3 answers
What happens for factoring algorithms if P=NP?
If someone ever demonstrates that P=NP, will it give us a polynomial factoring algorithm, or will it only tell us that such an algorithm exists, but we still have to find it?
tyuil
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