All Questions
29,521
questions
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19
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If mac M is defined as M(k,x) = f(k||x) where f is one way function, can M be UNF-CMA secure Mac scheme?
f here can leak inputs that is f(x1 || x2) = f(x1) || x2, is still a one way function (|x1| = |x2|). I don't think this should be a secure Mac but don't have any way to formulate it.
- 11
0
votes
0
answers
28
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RSA random key generation [duplicate]
How RSA keys are tested for primality if they are random generated? I imagine this could be time consuming task.
0
votes
0
answers
20
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Recursive snarks with a genus-2 no-cycle hyperelliptic curve?
Any hyperelliptic curve having base field characteristic dividing group order?
A subgroup of order equal to the basefield characteristic, a large prime?
Having hard DLP in that subgroup?
Having ...
- 2,287
0
votes
0
answers
17
views
Subkeys of multiple generated sets not combineable Shamir Secret Sharing
I am using a Shamir Secret Sharing implementation in Java and I have the use case,
that I may have to generate more Subkeys of the Secret after I already generated some.
Generating them works, but if ...
- 1
1
vote
1
answer
316
views
What is meant by software and hardware implementations? How to do it?
I have read many cryptographic papers or articles where I have came across about the software and hardware implementation for the cryptographic algorithms. I want to know how its been done. Is there ...
- 11
1
vote
2
answers
64
views
MAC from PRF secure under different restriction
Suppose, we have a secure PRF $F$. Then can there be a MAC Scheme $I=(Sign, Verify)$ using F such that $I$ is insecure, but I is secure under the restriction that all the queries for MAC challenges ...
- 11
1
vote
0
answers
62
views
Pseudo random generator notation
So I'm reading this article where they talk shortly about pseudo random generators where I'm not quite familiar with some of the notation. They call $\lambda$ the security parameter.
"...
1
vote
0
answers
32
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TR-31 Key Exchange Mode of Use
Using TR-31 key exchange, how is it possible to use restrictive modes of use, such as V (Verify only)? If Alice were to generate such a key, and send it to Bob, Bob would not be able to generate a MAC ...
- 149
0
votes
0
answers
66
views
Changing PRF at one value [closed]
If $F: \{0,1\}^n \times \{0,1\}^n \rightarrow \{0,1\}^n$ is a secure PRF with $n$ being the length of a binary string. We define $F'$ as
$$
F'(k,x) = \begin{cases}
F(k,x) & \text{if } x \neq 0 \\...
- 11
-2
votes
0
answers
32
views
Many Time Pad on cryptography [closed]
Let us see what goes wrong when a stream cipher key is used more than once. Below are eleven hex-encoded ciphertexts that are the result of encrypting eleven plaintexts with a stream cipher, all with ...
- 1
0
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0
answers
51
views
Does ISAAC really guarantee a cycle length of at least 2**40?
I just noticed that the FSE 1996 conference paper which defines ISAAC mentions a counter variable cc.
This variable is said to be the reason why ISAAC has a ...
5
votes
1
answer
112
views
Conformance of Windows Random Number Generator (SP800-90A) with Key Lifecycle Security Requirements of the BSI
The BSI (Federal Office for Information Security in Germany) has published a paper detailing the requirements of cryptographic modules for certain applications in the energy sector: Key Lifecycle ...
- 183
2
votes
0
answers
30
views
Is ISAAC+ actually an improvement over ISAAC?
I just tried to implement ISAAC from scratch, using the Jean-Philippe Aumasson paper from 2007 as a reference.
This paper gives a definition of the original ISAAC algorithm as well as the improved ...
3
votes
0
answers
43
views
Are there reputable public proving parameters for universal zkSNARK systems?
I have seen that Filecoin performed a public set-up ceremony for their zkSNARK system. Because Filecoin uses the Groth16 prover (which has a circuit-specific set-up), the output of this ceremony was ...
- 53
0
votes
0
answers
59
views
Using multiplicative hashing functions for hashing. Is it secure?
I recently started learning about hashing techniques and I read that techniques like multiplicative hashing techniques (for example using Fibonacci as a method of multiplicative hashing algorithm) are ...
- 23
0
votes
0
answers
73
views
Calculate SHA-256 for large data using finite memory space [closed]
I am embedded software developer I am working in cybersecurity project.
In the application I'm receiving 2000 bytes of data but the local buffer size is only 1000 bytes.
Currently I'm calculating the ...
- 1
0
votes
0
answers
20
views
How can A transmit a message m, addressed to B [closed]
**A and B are two participants, each with their own unique private key.
Private key A: k1
Private key B: k2
A and B can only use their own private keys. A and B do not share a common key that is known ...
0
votes
0
answers
43
views
Same message different nonce but similarities in r value of the signatures(r,s)
I'm studying a case where when i sign a same message with the same private key and a different nonce, i sometimes get signatures (r,s) where r values share some similarities (same numbers at the same ...
- 101
1
vote
1
answer
93
views
RSA signature with random padding
I used to think that adding random padding to an rsa plaintext was to prevent attack when you can ask/have access to different ciphered output, and decipher it without access to the private key (under ...
- 11
1
vote
1
answer
154
views
How to determine the prefix of a SECP256K1 compressed public key
I need to store a public key in a variable of maximum 32 bytes.
I recover the compressed key and remove its prefix, but then I have to do the opposite: I have to rebuild the compressed address from it ...
- 11
0
votes
0
answers
8
views
How to add Crypto++ library to NS3 using waf build system? [migrated]
1.I already downloaded the crypto++ 8.8.0 source code & moved them to a folder called cryptopp.
2.Furthermore, I have also created a wscript file in the cryptopp folder.
3.Now how should I proceed ...
- 1
2
votes
1
answer
126
views
48-bit nonce reuse with ChaCha20
The situation:
I have a group with 20 members, each member broadcasting 1 message per second. Communicating one on one is possible, but 1 message per member per second is the absolute limit and every ...
- 43
0
votes
1
answer
71
views
Is there any cheaper way for multiplying a plaintext scalar to a vector?
Assume I am using the SIMD encryption of homomorphic encryption. Performing plaintext-ciphertext multiplication between two vectors $\mathbf{a}$ and $\mathbf{x}$ means
$Dec(\mathbf{a} \times Enc(\...
- 33
0
votes
1
answer
66
views
Group secret agreement for clients do not have connection to each other
In my idea, $n$ clients will have the connection to a server, and clients will not be able to connect with other clients. Are there any previous design has been published to let $n$ clients agree on a ...
2
votes
2
answers
122
views
Textbook RSA using multiple low public exponent e
I'm working on finding an attack on textbook RSA using non-prime, low public exponents $e_1,e_2$ for each encryption.
Given $$c_1 = m^{e_1}\space mod \space n \\ c_2 = m^{e_2} \space mod \space n$$
I ...
- 31
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votes
0
answers
59
views
Client authentication: only talk to trusted clients?
As a preamble,I acknowledge that it is fundamentally impossible to authenticate
that a networked client is who they claim to be. The question is, given that
it's impossible, what should I do anyway?
...
- 499
1
vote
2
answers
192
views
PAGE 2: Can I move elements from cyclic subgroup to its cyclic parent group?
We will continue our previous topic here⬇️ for clarity...
The following context is based on elliptic curves in short-weierstrass form y^2 = x^3 + b.
pls read carefully-
I am looking for a function/...
- 21
0
votes
0
answers
35
views
Transmit a password to inheritors
I am looking for a safe and easy way for my inheritors to get a password after my death. That can be the password of a digital vault, a password manager, or anything else.
I could write the password ...
- 1
1
vote
1
answer
84
views
Could Yao's Millionaires' problem be used as a problem of binary search?
I recently started reading about Yao's Millionaires' problem. If the Yao's Millionaires' problem is capable of finding if one party has less money / more or equal money than the other party, then is ...
- 23
0
votes
0
answers
71
views
RSA encryption two characters at a time
I have a question in regards to a task I've been given at uni. I need to encode the string 'Cyber' 2 characters at a time with RSA with padding being space.
What do ...
1
vote
1
answer
62
views
Convert multiplication in $GF(2^{128})$ to bitwise AND?
Suppose we have $GF(2^{128})=F_2[x]/(x^{128}+x^7+x^2+x+1)$ and $a,b,c \in GF(2^{128})$ with $a*b=c$, where * is multiplication in $GF(2^{128})$. Could we convert ...
- 11
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votes
0
answers
52
views
Kyber and Dilithium usage limits?
What are the theoretical usage limits of Kyber and Dilithium? Are there any sources to back this up? Maximum number of encryptions/signatures allowed per key, etc.?
- 73
1
vote
0
answers
80
views
Zero Knowledge Proof for SHA-256 preimages
I need to design some protocol where actors will leverage Zero Knowledge Proofs (ZKP) to prove that they know the pre-image of some specific SHA256 hash without revealing the pre-image itself.
Ideally,...
2
votes
1
answer
71
views
Computing the intersection of two lattices
Given two lattices $L_1$ and $L_2$ represented by bases $B_1$ and $B_2$, is there an efficient algorithm to compute $L_1\cap L_2$?
I can show, I think, that if $\gcd(\det(B_1),\det(B_2))=1$, then $...
- 1,065
-1
votes
0
answers
59
views
Ethereum Money Loss: Seeking Help to Identify the Hacker [closed]
I hope this post finds you well, but I'm currently facing a significant problem that I need your help with. My phone was inexplicably hacked, leading to the loss of a substantial amount of money from ...
- 1
1
vote
1
answer
171
views
Can I move elements from cyclic subgroup to its cyclic parent group?
The following context is based on elliptic curves in short-weierstrass form y^2 = x^3 + b.
I know that elements of a non-prime order cyclic group G can be moved to its subgroup H by a process called &...
- 21
0
votes
0
answers
28
views
Decryption only on a specified future date?
Are there any encryption protocols or services that are time based. I.e I can encrypt something now and it can only be decrypted on or after 01/01/2100. Like a digital time capsule.
The only way I can ...
- 101
2
votes
2
answers
157
views
A question about "attacks on MAC key space"
At page 336 in "Handbook of Applied Cryptography - Menezes", I see the sentence
For $n$-bit MAC with $t$-bit key space this requires $2^t$ MAC operations, after which one expects $1+2^{(t-n)...
- 21
1
vote
2
answers
63
views
Zero Knowledge Argument for Elliptic Curve Multiplication/Inverse Multiplication Correctness?
I was reading this post and the accepted answer wrote about a way to “prove that some list of points $[A,B,C,...]$ when multiplied by $x$ produces $[A′,B′,C′,...]$”. However, in their explanation ...
0
votes
1
answer
45
views
Can we have an asymmetric key in AES? Clarification about PBKDF2 and AES-GCM in WebCrypto
Can we have an asymmetric key in AES? Clarification about PBKDF2 and AES-GCM in WebCrypto
According to wikipedia AES page, AES is a symmetric-key algorithm.
The algorithm described by AES is a ...
- 101
0
votes
0
answers
33
views
Java AES T-Tables Implementation
I am trying to implement an encryption function that uses the AES T-Tables implementation.
I am quite sure that my roundKeys are correct.
I also know that the initial round key addition in the ...
1
vote
2
answers
78
views
Efficiently detect that a ciphertext is meant for Alice
Assume we have the situation that Alice is receiving somewhere in the magnitude of 1_000_000 encrypted messages, whereby a small number (n<100 for 99% of cases) of these messages are meant for her. ...
- 315
0
votes
1
answer
58
views
Shamir Secret Sharing for API Authentication
I want to implement authentication for an API and thought about using Shamir Secret Sharing to do so.
My plan is to generate 1 Master Key which is stored in the Database, we then generate about 1000 ...
- 1
1
vote
0
answers
54
views
Trouble interpreting CTR_DRBG test vector results
I've implemented a CTR_DRBG random number generator according to NIST SP 800-90A Rev. 1 and I am now testing it with test vectors provided in NIST CAVS 14.3 (drbgvectors_no_reseed\CTR_DRBG.txt).
...
- 11
-1
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0
answers
78
views
Could we build PSPACE-based cryptography - more secure post-quantum? [closed]
It seems not safe to exclude possibility of e.g. some next generation quantum computers being able to attack NP problems (e.g. 2WQC) - so maybe it is worth to start thinking of shifting the ...
- 107
0
votes
0
answers
21
views
Nature of differentially private Laplace mechanisms
In the Wikipedia page on differential privacy, the section on $\varepsilon$-differential privacy for the Laplace mechanism says that the Laplace mechanism is specified for some output as $\mathcal{T}_{...
- 1
0
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0
answers
31
views
1
vote
1
answer
35
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Regarding the Digital Signature Algorithm During Client Authentication in TLS 1.2
In TLS 1.2, when client authentication is carried out, digital signatures are utilized. However, at what point is the specific signature algorithm communicated to the server? It seems to me that the ...
- 11
1
vote
0
answers
72
views
Is it better to use PBKDF2 with SHA-512 and 1e6 iterations or SHA-256 and 6e6 iterations?
I'm implementing encryption in my browser extension that will allow users to encrypt their data and then share them with others. And since shared links can be leaked, I want to protect the data as ...
- 111
-1
votes
2
answers
107
views
Encrypt with private key decrypt with public key
I want to sign and transmit a short message, which contains a few simple hashes. My objective is not to prevent an attacker from inserting a fake message, but to ensure that the attacker cannot define ...
- 99