All Questions
29,504
questions
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3
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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 ...
- 1
-5
votes
0
answers
9
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What is new math worth?
Methods of finding factors of numbers, not requiring regular factorization
https://www.ebay.com/itm/186093464767
https://www.ebay.com/itm/186093499754
https://www.ebay.com/itm/186093531060
0
votes
0
answers
6
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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
0
votes
1
answer
74
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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 ...
- 21
0
votes
1
answer
45
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
56
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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
105
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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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0
answers
58
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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
0
votes
2
answers
138
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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/...
- 11
0
votes
0
answers
32
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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 ...
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1
vote
1
answer
78
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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
67
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
53
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
0
votes
0
answers
46
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
76
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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,...
-1
votes
1
answer
47
views
Padding oracle attack when padding is on prefix
Is there any attack on padding Oracle AES-CBC encryption when padding is added as a prefix instead of suffix or is it secure completely
2
votes
1
answer
61
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
56
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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
153
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 &...
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0
votes
0
answers
26
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
149
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
58
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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
40
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
31
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
72
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
52
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 ...
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1
vote
0
answers
44
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).
...
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-1
votes
0
answers
77
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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
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votes
0
answers
21
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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
votes
0
answers
28
views
1
vote
1
answer
34
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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
71
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
0
votes
2
answers
84
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 ...
- 101
1
vote
0
answers
26
views
Function Secret Sharing
Bob has constructed a non-linear function $f: \mathbb{R}^n\rightarrow \mathbb{R}^m$ of moderate complexity (i.e., evaluation takes on the order of seconds on a modern computer). Is it possible to ...
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0
votes
0
answers
21
views
Discrete Gaussian distribution on a lattice vs. the periodic Gaussian function on a lattice
Gaussian distribution on lattices generally seems esoteric (at least for me, for now). My question is:
Does Gaussian distribution on a lattice mean to add a Gaussian noise on a single point of a ...
- 347
2
votes
1
answer
67
views
Would encrypting several layers of a filesystem be a waste?
I've been thinking about ways to improve the security of my data stored and backed up using the "3-2-1" method.
Moreover by using several layers of encryption to encrypt and decrypt a ...
- 21
3
votes
0
answers
95
views
Who originally generated the elliptic curve now known as P256/secp256r1
Background: there is a theory going around that claims that P256 was backdoored by the NSA. The theory goes is that the NSA found a weakness that applies to a nontrivial fraction of elliptic curves (...
- 143k
0
votes
0
answers
80
views
How to "break" this PRF scheme?
I'm new to cryptography, and I'm working on exercises that involve "breaking" PRF schemes which involves writing a poly-time program that distinguishes between two particular programs, the ...
4
votes
0
answers
69
views
Masking countermeasures for AES-GCM
Suppose I have a masked AES encryption $AES(\oplus_i K_i, \oplus_i P_i)=\oplus_i C_i$, i.e. the key, plaintext, and resulting ciphertext are tuples $K_i$, $P_i$, and $C_i$ that sum to $K$, $P$, and $C$...
- 327
0
votes
0
answers
18
views
Question on Aleo zkVM
Can we use array as the input of a transition/function? Just like:\
transition testarr(arr: [u32; 3]) {
}
I saw some tutorials that have examples of this but now ...
- 61
1
vote
3
answers
55
views
Zero-Knowledge Proof of Encryption with a Specific Key
Short version:
Given a hash of a plaintext, a public key, and a ciphertext (but not knowing the original plaintext), is there any way to verify that the ciphertext is the plaintext after being ...
- 111
2
votes
3
answers
450
views
Check if encrypted text is equal without decrypting or doing heavy calculation - AES
I implemented AES128-CBC algorithm and what I need is to be able to compare encrypted text without decrypting. Is the only way to use static or no iv to achieve this? I wanted to create only field ...
- 23
0
votes
0
answers
28
views
How IV value shapes the State Matrix of PHOTON AEAD?
In PHOTON-Beetle Authenticated Encryption algorithm, the state consists of 64 4-bit
elements, which is represented as a (8 × 8) matrix. The Initial Value which consists of Key and Nonce from the ...
1
vote
0
answers
42
views
Is the SNI extension signed in TLS 1.3?
In TLS 1.3, and since the server signs the entire handshake messages including the server hello message, in this case, is the SNI extension of the client hello message, is it included in the content ...
- 33
0
votes
0
answers
25
views
Interacting with Zksync sometimes returns an "invalid value for value.blockHash" error
I've been sometimes getting this error while interacting with zksync "invalid value.blockHash" and have been unable to find information about it elsewhere. What's curious to me is that it ...
2
votes
1
answer
130
views
Does using a block cipher in CBC mode *twice* result in an all-or-nothing transform (AONT)?
Use a block cipher in CBC mode with a public or all-0 key. Twice.
Wrapping the last block into (xor) the first on the second round.
Every block will depend on all previous and all successive blocks. ...
0
votes
0
answers
61
views
HMAC-SHA256 key length against key recovery attack
I have trouble finding information on the security strength of HMAC-SHA256 against key recovery attacks with respect to the key size.
To fit a certain application I must use a 128-bits key with a HMAC-...
0
votes
0
answers
47
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Sagemath help: Introduction to Lattices
Hi im doing a problem from the Chapter Lightweight Introduction to Lattices in "Learning and Experiencing Cryptography with CrypTool and SageMath"
I'm curious if my implementation is wrong ...
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0
votes
0
answers
36
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2 XORed AES-ECB ciphertexts, zero key and piece of plaintext
I have $C_1 \oplus C_2$ where $C_1$ = $AES128_k(P_1)$ and $C_2$ = $AES128_k(P_2)$.
I know the k, it is 0 (i.e. 16 bytes of zeros).
I know the piece of $P_1$ (7 ...
- 1
0
votes
0
answers
11
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what is (n, n’, δ, u) generalized BBS assumption？
This assumption appeared in the 2000 'timed commitment' to justify privacy in the scheme. But it is not known what the relevant symbols mean in this hypothesis.
