# All Questions

20,389 questions
Filter by
Sorted by
Tagged with
0answers
14 views

### Tiny AES vs AES algorithm

Is Tiny AES algorithm any different from the standard AES algorithm. I have come across mentions of Tiny AES at a lot of places but none which define it's architecture.
0answers
10 views

### Proposed Mental Poker Protocol [on hold]

I created two files for this, a public one here https://pastebin.com/wH9ahn86 and a private one with the deck and the mask. Please recover the mask.
0answers
7 views

### How to decrypt a combination of anagram and substitution cipher text

I'm having problems decrypting a cipher text that has an anagram applied to it but also a substitution cipher. I don't know in which order they were applied. Does anyone know what steps I should ...
1answer
21 views

### Termonology help: What is using AEAD without encrypting data called?

I'm using ChaCha20-Poly1305 in a "full AEAD" mode, where a payload of data is encrypted and a block of unencrypted "additional data" is secured as well. However, I'd like to also occasionally use the ...
0answers
15 views

### Encryption/Decryption algorithms for real-time use [on hold]

What characteristics should an encryption/decryption algorithm have, in order to make it capable of used in real-time data? For example RSA which is so unbreakable I can't find an implementation of ...
1answer
19 views

### Splitting text before Format Preserving Encryption operation

What is the effect on Format Preserving Encryption security if I reorder text before FPE encryption? Take as an example Canadian postal codes (letter-digit-letter digit-letter-digit): Parliment: K1A ...
0answers
16 views

### Encryption key using the encrypted text and unencrypted text [on hold]

I was hoping someone could help me find the encryption key for the plain text: 10100011 and encrypted text of: 00000000
0answers
7 views

### random change of PRNG seed during cyphering process [migrated]

I use a home made python script for private local storage using XOR one-time-pad. The key file is generated by using the PRNG provided by the "random" built-in module of python. As the size of the ...
0answers
11 views

### Non interactive threshold signature without bilinear pairing (is it possible)?

All threshold signature schemes that I have seen need bilinear pairings to avoid parameter exchange between parties. These are normally commitment schemes for a certain secret. I believe a 2-round ...
3answers
555 views

### Suppose I capture encrypted data that I want to decrypt. Could I use a server farm to decrypt?

For argument's sake, let's say that I'm a bad actor who produces malware. I've infected around 10,000 computers and smartphones with my malware, which runs in the background and can be used to make ...
1answer
38 views

### Multivariate cryptography - easily invertible quadratic map

I am reading through multivariate cryptography and in every source I have seen, the secret map $P$ is described as "easily invertible" or "easy to invert". What exactly does it mean "easily ...
0answers
17 views

### Decrypt a file that has been encrypted using libgcrypt library [migrated]

I encrypted a text using libgcrypt with AES256 CFB and saved it in a file. Why can't I decrypt the file on command line with gpg -d ? I can decrypt the file using libgcrypt.
1answer
56 views

### Proving a secret is known without revealing it

Let's say Alice wants to prove to Bob that she knows a secret S that Bob is also supposed to know. Alice can't be sure Bob is really who he pretends to be, so she needs to make sure Bob can't deduce S ...
1answer
30 views

### Can the OpenSSL random number generator be considered cryptographically secure? [duplicate]

The OpenSSL Random Number generator documented here uses an OS-provided entropy source coupled with a MD5 hash function. Does it impact the quality of randomness to use a broken cryptographic hash ...
0answers
24 views

### Problems about parameters configures of Herrmann and May's method to solve linear modular equation

I'm reading Herrmann and May's paper; they introduced a method to solve multivariate linear equation modulo unknown divisors. It's shown in Table 1 that, for an 512-bit RSA modulus N with divisor p ...
1answer
57 views

### Supercomputer to crash hash

For NVIDIA TESLA V100 I know a hashcat performance for SHA1: it is about 17000 MH/s. Performance index for V100 is FP32 5120, FP64 2560. But what about supercomputers? For example Summit ...
0answers
32 views

### decrypting a one-time-pad that outputs 0,1 in preknown probabilities

assuming a two users want to use a one time pad ciphersystem, and they are using a program that was developed by a third party that was supposed to create random undependable bits, but for some reason ...
0answers
18 views

### Polyalphabetic rotation cipher over digits [on hold]

what is the keyspace of a poly-alphabetic rotation cipher over digits, with a repeated key-length of 2, in which no digits can encrypt to itself? Why is the answer 72?
0answers
41 views

### Why doesn't WhatsApp encryption multiply file size [duplicate]

WhatsApp uses and end-to-end encryption, on both personal and group chats. According to my understanding, that means every message I send to a group is encrypted on my Device for every group member ...
1answer
66 views

### Order of subgroups formed by Elliptic Curves with a Cofactor

In this question: Why are the lower 3 bits of curve25519/ed25519 secret keys cleared during creation? The answer indicates that the order of all points on the curve over the finite field ...
0answers
34 views

### Does SET in any way use SSL?

I just started a course in web security, and I was just wondering quickly if SET in any way would use SSL? I noticed it was developed in part by Netscape. But all I can find is comparisons between the ...
0answers
24 views

### How to perform ByteSub transformation? [duplicate]

Can anybody please tell me how do we perform ByteSub transformation of AES to 01001001.
3answers
458 views

### Why are in asymmetric cryptography as many keys as people involved needed?

The question: "10 friends wish to establish secure communications between themselves using asymmetric-key cryptography. How many keys need to be known by each user?" was posed by my teacher. He says ...
0answers
29 views

### How to show that Affine crypto have a valid decryption

I just need to know how to attack a question I have in my textbook this is like: Let $E_1 (x) \equiv 17x + 7 \pmod{28}$ and $E_2(x) \equiv 23x + 11 \pmod{28}$ be encryption functions for two ...
0answers
18 views

### Will CT (Certificate Transparency) override the use of CAA and/or DANE/TLSA records?

I'd want to know if some of these competing technologies has more chance to survive. It seems they are thought to solve a similar problem by different manners and I'd want to stick to the most ...
1answer
44 views

### Generate private key from public key RSA

I am doing a tutorial where my lecturer (PhD) gave me an optional question to do relating to RSA. He said: write a python function that takes as input the server’s public key and then uses that to ...
0answers
30 views

### What are the advantages of runtime defenses vs. compile-time defenses against buffer overflow? [on hold]

What are the advantages of runtime defenses v compile-time defenses against buffer overflow attacks?
1answer
67 views

### Text encryption algorithms that can be used and are secure

what text encryption algorithms are being used nowadays that are secure? Obviously I am not interested in DES or 3-DES that google shows me and which can break...
2answers
99 views

### What is a multi-target attack?

What exactly is a multi-target attack? How does the attack work on different cryptographic schemes (block ciphers, hash functions, elliptic curves)? How can it be avoided?
0answers
22 views

### Zero knowledge proof that ElGamal ciphertext encrypts the opening of Pedersen commitment

Given ElGamal ciphertext for a message $m$ with a random $r$ as $(c_1,c_2) \gets (g^r, g^my^r)$ for a public key $y$, and a Pedersen commitment $C \gets g^xh^r$, I have been able to create a proof ...
1answer
242 views

### Is length extension attack considered as collision?

I came across a few articles about length extension attacks on cryptographic hash functions. I was very surprised to read that SHA-256 and SHA-512 are prone to length extension attacks. This seems ...
1answer
67 views

### Choice of finite fields for use in elliptic curves

this is maybe a basic question but I'm trying to better understand elliptic curve cryptography at a fundamental level. I understand that a finite field is required in order to define a boundary for ...
0answers
52 views

### one hash for two (or more) different input values

(edit 21.11.2019): Verbosity of problem statement was to add context. I take the suggestion in comment and edit this question to have only mathematical problem. fgrieu succintly summarized the ...
0answers
13 views

### Is there any existing Threshold Authorization Token?

By Threshold Authorization Token I mean a token (similar to a JWT) that is produced by a (t,n)-threshold scheme. I'm trying to gather background on the subject, but it's hard to find anything, if ...
1answer
37 views

### RSA decrypt message with low public exponent (n = 187, e = 3 and C = 185) [on hold]

n = 187 e = 3 C = 185 How to decrypt message? I know there is some way using cryptogram exponentiation. Can you give me a hint?
0answers
16 views

### Zero knowledge proof with accumulators

I am working on a proof of concept on cryptographic accumulators. delta: The current size of the tails file in the accumulator. witness: The current value of the accumulator when the entry of your ...
0answers
40 views

### Where are labels of a Labeled data used in homomorphic message authenticator stored?

In a fully homomorphic message authenticator, Alice can authenticate some large data $D$ using her secret key $s$k. She chooses a label $\tau$ for it, and the authentication algorithm authenticates ...
0answers
25 views

### Change windows live mail password?? Issue [on hold]

Gentlepersons, I am using Windows Live Mail as my e-mail program at the moment. I've been using it without a question for several years ... until recently. I've had problems with changing my e-mail ...
1answer
49 views

### Do garbled circuits run in constant time?

It seems like garbled circuits should not be input dependent, and hence should always run in constant time. Just wanted to clarify if this is true.
1answer
53 views

### Why do we use prime numbers apart from hard factorization?

Why are prime numbers important in cryptographic constructs? I am not interested in RSA examples where factorization is the hard problem itself, that makes sense. However wherever I go I encounter ...
0answers
24 views

### What does the server do on receipt of a one-time-password?

I'm trying to understand this question and I do not understand part of it. I have part of figured out, part of it not. Considering the hash function h(i) = (i + 5) mod 7, used in an implementation ...
1answer
48 views

### Is a keyed MAC sufficient for integrity protection?

I'm working with the above figure which shows a challenge-response protocol. ...
0answers
31 views

### NTRU Bilateral Key Exchange

With the NTRU scheme, is the key exchange only done by encrypting a symmetric key with the recipients public key (+ authentication) or can something similar to DH/ECDH be done, where public ...
1answer
51 views

### If there is an algorithm A can calculate the modular square root of input n, How to use it to get prime factors?

Suppose you are given an algorithm $A$ which takes $y \in \{0, 1, \ldots , N − 1\}$ as input, and outputs $x \in \{0,1,\ldots,N − 1\}$ such that $x^2 \equiv y \pmod{N}$. Design an efficient, ...
1answer
80 views

### Why does curve25519 use a cofactor of 8?

This cofactor (as I understand it) effectively discards valid points that satisfy the curve equation over the finite field. Why would one wish to reduce the number of possible private keys, it seems ...
1answer
43 views

### Is there a point in storing hash or plaintext in the last column of Rainbow Tables

As I read up on rainbow tables, I found that most sources suggest storing a plaintext - the result of Rk(hk) - in the last column, while others just store the hash hk, basically stopping one step ...
0answers
23 views

### Key exchange and authentication using libhydrogen

I have been able to exchange session keys on two devices using Libhydrogen's Key exchange using the N variant method. I also want to authenticate both devices to have some protection against the Man ...
1answer
109 views

### Is this problem based on discrete polynomials modulo $(x^3-1)$ strong?

We start working with the Ring $R=\left(\mathbb{Z}/p\mathbb{Z}\right)\left[x\right]/\left(x^{3}-1\right)$, $p$ prime, i.e. degree two polynomials with coefficients modulo $p$ modulo $x^{3}-1$. As \$x^{...
1answer
28 views

### difference between function f in eval and dec of homomorphic authenticated encryption

In the homomorphic authenticated encryption, as described 1, there are Eval and Dec PPT algorithms: In Eval, f is the function to be performed on the encrypted data. However, I need to know why it ...
1answer
159 views

### Do any NIST PQC have “homomorphic” public keys, in the sense that any two pubkeys derive a combination pubkey?

Background: The MathMesh crypto platform (refs at the bottom) is a newly-proposed technology stack which has been somewhat cheekily called a "Grand Unified Theory of Security on the Internet". Its "...

15 30 50 per page