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1answer
25 views

Group Signatures with VLR Revocation Check

I was reading the paper by Boneh et al. Link. The scheme describes what is called a Verifier Local Revocation Technique. The Scheme assumes that a Revocation List [RL] allows each verifier to check ...
2
votes
1answer
64 views

Is there a cryptosystem which allows slicing and concatenating strings without decryption?

I want a cryptosystem with the following four functions: ...
0
votes
0answers
4 views

tshark decryption fails on old OS but succeeds on new OS [migrated]

I have a pcap tracefile and private RSA key that should allow me to decrypt the HTTPS data in the pcap file. With the exact same pcap file, private key and tshark command, I find that decryption ...
0
votes
1answer
39 views

One-way Functions for Floating Points

Are there any commutative one-way functions for floating points? I tried to explain why I need these functions. First, I describe the problem on a high level and then I further formalize it; There ...
1
vote
1answer
48 views

Sum vector elements homorphically

I'm looking for the homomorphic version of the following (I'm using Python here): $ a = [1,2,3] $ s = sum(a) $ print(s) 6 Is there an open source fully ...
2
votes
1answer
34 views

Reference for the Security Analysis of Ring-LWE

Can someone please share a link of any research paper or web-page analyzing the security of Ring-LWE? Essentially, how should I choose my parameters to get security equivalent to 128-bit or 256-bit?
0
votes
1answer
54 views

Observing cipher suites and certificate algorithms without man-in-the-middle

I manage a proxy server. Is it technically possible to observe and determine which cipher suite is selected between end points (client and server) without changing their SSL certificate, without ...
0
votes
1answer
44 views

Two point addition in elliptic curve using sjcl library in javascript [closed]

I am new to SJCL library and I am working on elliptic curve cryptography at very basic level. I can't implement the add function for two points on the elliptic curve. The signature of add function ...
0
votes
1answer
36 views

Most efficient way to break md5?

if you know the result of a hash, for this example the resulting hash is: ec664d1d65fd8a58c59b337b11c37a4d And you also know the hash has been made like this: <...
0
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0answers
12 views

Arbiter Physical unclonable function [migrated]

I do not understand why my verilog code doesnot produce output of arbiter puf when I am trying to implement on fpga. ...
-1
votes
0answers
23 views

How to identify cryptocurrency used by the public key of the recipient?

I though that it would be an easy task, but I can't seem to find any online resource to help me with it. Say, if I have a cryptocurrency key of the recipient, how can I tell the name/type of the ...
2
votes
0answers
44 views

How does ZK-snark work in zcash?

For a public one-way function $f()$, we can use zero proof to prove I know some secret $x$, such that the output of $x$ is a specific number $y$. However, in zcash, I need to prove that I have some ...
-1
votes
1answer
64 views

Is a number generator based on hashing an incremental string and a seed considered random? Part 2

Sorry I didn't put enough details on my last question, I didn't expect that there is really lots of factors, so most answers were left for speculations. In this question, I will give the scenario I am ...
1
vote
1answer
47 views

IEEE P1619/XTS, inconsistent reference implementation and test vectors

I'm testing IEEE's P1619, which is XTS mode. IEEE documents from 2007 provided both test vectors and a reference implementation. Documents from 2008 only provided the reference implementation. Here is ...
0
votes
1answer
36 views

Which groups to use for Pedersen Commitments

I have been reading about Pedersen Commitments, and have come across some contradictory examples, which is confusing. Just focusing on simple commitment of scalars (not EC points or vectors), then I ...
0
votes
0answers
29 views

Unconditionally secure message authentication, how does it work? [duplicate]

The definition of an unconditionally secure cryptosystem is that it cannot be broken even with infinitely computational resources and time. The one-time pad (OTP) is an example of an unconditionally ...
0
votes
1answer
32 views

Question on the Quadratic Residuosity Assumption

I am reading the Handbook of Applied Cryptography and on page 99 the authors write , after showing that $QRP \le_P FACTORING$: It is believed that the $QRP$ is as difficult as the problem of ...
2
votes
1answer
139 views

How does Gilbert, MacWilliams, and Sloane's solution to “perfect integrity” work?

Gilbert, MacWilliams, and Sloane defined a solution to "perfect integrity" in Codes Which Detect Deception, unconditionally secure message authentication, not vulnerable to any cryptanalysis on its ...
1
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0answers
27 views

Algorithms for solving systems of quadratic multivariate polynomials

What are the best algorithms for solving systems of $k$ polynomials equations where these are quadratic multivariate polynomials on $k$ variables? I've encountered such systems on my research and I'm ...
0
votes
2answers
75 views

Is a number generator based on hashing an incremental string considered random?

Consider the following system 1 - fixed string as a seed, example "something" 2 - concat an increment number "something-1" 3 - hash it, assume it is "9f2054ea4d2c" 4 - take the first 3 digits to ...
1
vote
1answer
62 views

Can we use BLS as a VRF?

Intuitively, it seems that the hash of a BLS signature could be used as a VRF as well. In a nutshell, BLS-Signature is the VRF output and the verification first ...
2
votes
1answer
200 views

Decrypting Multi-Prime RSA with e, N, and factors of N given

I was wondering if there was any way to compute the private key $d$ when knowing only $e$ and $N$, and being able to factor $N$ as 4 prime numbers $p, q, r$ and $s$. I've been searching for days and I ...
1
vote
0answers
47 views

Homomorphic Public/Private Key Encryption Scheme for Floating Numbers

Is there any public/private homomorphic encryption scheme that directly works on floating numbers or vectors of floating numbers? In our application, we want to find out if $$v_1 \approx v_2, \qquad\...
3
votes
2answers
54 views

What are the actual merits of Galois/Counter Mode?

GCM (Galois/Counter Mode), in particular in combination with AES, has been a de-facto gold standard for years. Encrypt and authenticate in one step, that's just too awesome, and terms like AEAD work ...
2
votes
1answer
92 views

“Jitterentropy” vs CPU RDRAND in VeraCrypt 1.24

Veracrypt 1.24 just came out. It uses a true random number generator based on hardware events; namely, on CPU timing jitter, or "Jitterentropy". As an alternative to CPU RDRAND, I am a bit jittery ...
4
votes
1answer
141 views

How were the arbitrary values used inside SHA-256 algorithm determined?

I am studying the SHA-256 algorithm, and I am wondering something about it. How were the values used inside of the algorithm determined? Take a look for example at how the 16-64th Words are generated....
0
votes
4answers
871 views

Why do one-time pads not provide message authentication?

It is often said that one-time pads do not provide message authentication. But, if you and I have a one-time symmetric key, and I send you a message, and it is not complete gibberish, is that itself ...
0
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0answers
6 views

Can reducing NP problems to subset NP Problems leed to faster calculation of NP problems [migrated]

Integers can be represented with a pair of smaller numbers. To achieve this I use 2 integer sequences. Integer Sequence 1 1,1,2,1,2,3,1,2,3,4... And Integer Sequence 2 1,2,1,3,2,1,4,3,2,1... This ...
0
votes
0answers
39 views

Is attack against secret prefix possible for messages of any size?

I am aware of message extension attack on MACs constructed with a hash function that uses Merkle-Damgård scheme. $$MAC=h(k,x)$$ I am interested if this attack only works if $0 ≡ x$ mod (hash input ...
2
votes
2answers
101 views

Fiat Shamir transformation of zero knowledge proof

Consider the following three stage interactive zero knowledge proof The prover sends some information $a$ to the verifier. The verifier picks a challenge $c\in \{0 ,1\}$ Depending on the challenge, ...
0
votes
0answers
5 views

Sign Verify problem by provider in JCA [migrated]

I'm trying to sign and verify my data with SHA256withRSA,MD2withRSA,SHA1withRSA,SHA512withRSA modes. My provider supports all of them but, just MD2 mode works for my code. Other ones does not work, ...
0
votes
0answers
7 views

ECDSA Public key recovery [migrated]

Helo, I try to recover the public key from cookie, here is what i've done, not sure if thats correct... 1) Register and login to get the cookie: ...
1
vote
0answers
22 views

Secret key suffix vs HMAC [duplicate]

What is the benefit of using HMAC over hash with key suffix? I realize that using key prefix is a bad idea because it allows message extension attacks. When adding key as a suffix such attack ...
1
vote
1answer
53 views

How do I interpret the CADO-NFS output for discrete logarithm calculation in GF(p)?

I'm using CADO-NFS to calculate discrete logarithm in a finite field GF(p). The problem is when I type ...
0
votes
1answer
62 views

What are the random variables in Universal Hash Function?

Universal hash function is defined as follow: $f_{(k_0,k_1)}(x) = (k_0\cdot x + k_1) \mod p$, where $p$ is prime In Wikipedia, it is mentioned that the above function is pairwise independent. ...
2
votes
0answers
45 views

Encrypted ZIP and plain text attack [duplicate]

I have a Zip archive containing a single password-protected file file.txt. The encryption is "ZIP 2.0 Default Encryption" (ZipCrypto). I know what kind of text (...
2
votes
0answers
39 views

What is optimal error distribution in Ring-LWE?

I am new to Ring-LWE. I had assumed that error distribution in Ring-LWE (or, in any lattice-based cryptography) is always Gaussian. However, while reading a few research papers (e.g. page 5, Section "...
1
vote
1answer
78 views

Paillier Private $\mu$ and $\lambda$

The Paillier CryptoSystem has a public key that $(g,n)$ and the private key which can be exclusive to $\lambda$, where the decryption scheme is: $m = L(c^\lambda \ mod \ n^2)/L(g^\lambda \ mod \ n^2)\...
0
votes
0answers
6 views

How to use SHA-512 in terminal? [migrated]

I do not understand this problem. I tried my code down below. It says,"can only sign or verify one file." Instructions: Using the hash function SHA‐512 and the key ...
1
vote
1answer
75 views

SHA3-512 troubleshooting - is there a worked example for hashing the “zero-length string”?

(I wondered if this question should be asked on StackOverflow instead because it's a programming related issue, but it's bound to the intricacies of SHA3, which I figured was a better fit for Crypto....
5
votes
1answer
75 views

Can Trivium be used as a PRF?

The Trivium encryption algorithm has two inputs, key and IV, both of which are 80 bits long. Let's call it Trivium(key, IV) → keystream. My question is whether doing Trivium(key, input) and taking the ...
2
votes
0answers
28 views

ASCII characters in an image steganography [duplicate]

Given an image size of 300 by 400, what is the maximum number of ASCII characters (7 bits) that can be embedded using the LSB steganography? I would assume that every pixel can perform an LSB so ...
1
vote
0answers
43 views

Is the 51% attack the only technical reason no country will ever adopt Bitcoin as a state currency? [closed]

Is the 51% attack the only technical reason no country will adopt Bitcoin as a state currency? Let's suppose a country with a GDP size less than 300 Billion USD adopt the Bitcoin as an official ...
0
votes
0answers
17 views

How to create a generator for a $Q_3$ access structure?

I'm reading about access structures used for multiparty-computation from https://eprint.iacr.org/2004/245 and https://eprint.iacr.org/2000/037. My understand is that to actually use the access ...
0
votes
3answers
157 views

CRC32 catches errors, but then what's the point of SHA?

If crc or CRC32 is specially designed to catch errors, then what's the point of SHA or md4-5 or any other hashing function? What I did was, I had a 190 mb png file (rendered in 16k resolution with ...
-1
votes
0answers
57 views

In RSA, how do you find d with a very large e?

If I had N and E, how would I be able to find D? The catch here is E is extremely large -> like 310 digits. I think this set of numbers is vunerable because E should be relatively small. How can I ...
0
votes
1answer
33 views

Byzantine Agreement: Why does OM need f+1 rounds in a synchronous setting?

To get Byzantine Fault Tolerance in a synchronous model you can use an Oral Message Algorithm. For n > 3f+1 it gets an Byzantine agreement in ...
0
votes
3answers
90 views

Derivation of birthday paradox probability

I am trying to come up with an explanation of the probability of birthday collision. $P$(no collision among t people) = $(1− \frac{1}{365}) · (1-\frac{2}{365}) ··· (1-\frac{t-1}{365})$ For one ...
1
vote
1answer
38 views

Paillier Complex Residuosity problem?

Paillier Cryptosystem depends on both the factorization where $n = p.q$ and the complex residuosity problem which is defined in the original paper as: The problem of deciding n-th residuosity, i.e. ...
0
votes
1answer
83 views

Using a classical method, is it possible to create a key that is indistinguishable from one made in a truly random manner?

Is there a classical method that will allow us to create a key that cannot be distinguished from one that was generated in a truly random manner? For example, let's say we use three "words" to create ...

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