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23 views

find the relationship between the key and cipher text in hill cipher [closed]

suppose that for a hill cipher the plaintext is a multiplicative identity matrix (I) find the relationship between the key and ciphertext. use the result of your finding to lunch a chosen-plaintext ...
-1
votes
0answers
22 views

can someone help to modify/extend AES or Blowfish algorithm for me? [closed]

I want to carry out a modification or extension on AES or Blowfish to reduce the memory use and encryption/decryption time but I don't know how to go about it at all. please help
0
votes
1answer
27 views

Vulnerability of low value generated key

I have read here that Elgamal is resistant to brute-force attack, because the group to where the key is selected is very large. But since the key generation is random, (i assume)there is a chance that ...
2
votes
1answer
43 views

Does the discrete log assumption hold if k > p

In discrete log cryptosystems like ElGamal it is noted that the "private key" $k$ should be chosen as any element of the group $G$ i.e. $k < p-1$. Does the integrity of the cryptosystem rely on $k$ ...
0
votes
1answer
30 views

Can I Implement a Well-Trusted Protocol with Well-Trusted Libraries in JavaScript securely?

Just for anyone reading this: DO NOT ROLL YOUR OWN ALGORITHM. Besides that, is implementing a well-trusted protocol with well-trusted algorithms and libraries a good idea? Is this likely to ...
0
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0answers
26 views

There are 3 factors in RSA [duplicate]

A Variant RSA. $n$ has 3 factors $p,q,r$. $\gcd(e,\phi(n))=1$, can decrypt it like normal RSA,or should use chinese remainder theory to decrypt it?
5
votes
5answers
427 views

Why use complex encryption algorithms? [duplicate]

I have recently gotten interested in cryptography, so I looked some things up. I thought, why even use AES or DES or any other complex way for encrypting data when there are far simpler ways, like ...
1
vote
1answer
68 views

SHA-256 : Finding two strings that the first n bits of hash value are same [duplicate]

How can I find two strings that have the same hash value for first $n$ bits in SHA-256? I'm implementing it by Python and I have the following ideas and problems: Keep generating two random string ...
-2
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0answers
39 views

Are the type of integer lattices and other approaches intended to make Bitcoin quantum resistant just one time pads? [closed]

https://en.m.wikipedia.org/wiki/Post-quantum_cryptography They are just proposing using a lattice to scramble a message and then the recipient using a public version of the lattice to unscramble. Isn'...
0
votes
1answer
13 views

Are HAIFA-construction based hash functions (e.g. Argon2) resistant to length-extension attacks?

Would a HAIFA-construction based hash function like Argon2 resistant to length-extension attacks? I say that Argon2 is HAIFA-based because BLAKE is, and Argon2 is based on BLAKE.
0
votes
1answer
59 views

False positives in a signature scheme [on hold]

Let's considerer a bloom filter: there, we can include witness of membership; false negative isn't possible, but it can exist some significant probability of false-positives. But, what if we demand ...
0
votes
1answer
42 views

Can I use a government-issued certificate in Outlook? [closed]

My government issues certificates for many purposed, including e-mail signing. The government doesn't provide e-mail addresses, but it does declare my e-mail in the certificate. Can I use this ...
2
votes
1answer
112 views

What's the point of hiding the key in white box cryptography if the attacker already has full access to the encryption (or decryption) implementation?

The attacker doesn't need the key in order to decrypt ciphertexts or encrypt plaintexts since he/she already has the full implementation. So what's the point of hiding the key? What advantage would ...
2
votes
0answers
63 views

Known Plain-text Attack [closed]

How can I find the known plain text P2 based on the given information? Assuming that the encryption is made using a common initialization vector and the mode used for encryption is OFB. ...
3
votes
2answers
70 views

TLS 1.3 Security against PKCS#1v1.5

This paper explains an attack on TLS 1.3. This was published way back in 2015 when TLS RFC was in draft stage. My question is now TLS 1.3 RFC is finalized, is this attack got addressed?
1
vote
1answer
35 views

Retrieving correct ciphertext from additive ElGamal

I have been studying additive ElGamal and I think I have the hang of it except the part where the message $M$ must be retrieved by computing the discrete log of $g^M$. From what I've read, the ...
-1
votes
1answer
70 views

Block cipher mode of operator with counter as part of its key or message [closed]

Consider a block cipher (such as AES256) as $E$, a randomly selected key $k$, a counter $i$, and an array of n-bits $M$ as the message. Also consider the following block cipher modes of operations: $...
2
votes
2answers
63 views

Collision resistant functions - definition

Let $f$ be a collision resistant function i.e. it is computationally impossible to find $x_0, x_1$ such that $f(x_0) = f(x_1)$. If a computationally bounded adversary demonstrates that he knows some $...
1
vote
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
63 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
38 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
35 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
63 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
46 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
31 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
137 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
74 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
49 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
198 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
45 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
52 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
91 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
867 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
votes
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
96 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: ...

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