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If a password is randomly chosen from a space of $2^{64}$ passwords and is stored as an SHA-256-bit hash and a 128-bit salt, how many hashes does an attacker need to perform to recover the password in the worst case?
Would it just be $2^{256}$ hashes because SHA-256 provides $256$ bits of security in a pre-image attack... |
To encrypt plaintext $(P_1, P_2, P_3, ... P_n)$ Ciphertext Feedback Mode (CFB) works as follows :-
$$
C_0 = IV \\
C_i = E_K (C_{i-1}) \oplus P_i
$$
Lets define a modified version of CFB mode as follows :-
$$
C_0 = IV \\
SK_i = KMAC(K, C_{i-1})\\
C_i = E_{SK_i} (C_{i-1}) \oplus P_i
$$
The modified CFB mode encrypts each... |
If an attacker wants to hack the passwords of $2^{10}$ users. And all of these users generate a password from the space of $2^{50}$ passwords** and each password is hashed with PBKDF2 with $2^{10}$ iterations**.
How many hashes would an attacker need to do to get all passwords in the worst case?
I was thinking it would... |
Could you explain the difference between sigma protocol, Schorr protocol with examples. What is the advantage of using commit-and-prove zero knowledge proof over general zero knowledge proof?
|
I have recently understood how we can construct a pseudorandom function from a PRG. However, I would like to prove the reverse - how can I construct a PRG from a PRF?
|
Is there any generic attack on HMAC SHA 256 ?
I am currently reading up on attacks on Hmac sha-256. However most of the papers I've found are about side channel attacks such as Differential power Analysis.
|
How do I calculate the password space of a randomized linked hybrid pasword of 9 images and 10 numbers(0-9)? User allowed to select 4 password
Images=9
Pin= 0-9
Password selection allowed: 4
Every image is linked to a number
Images are randomized at each selection
|
Going through the TPM tutorial: https://google.github.io/tpm-js/#pg_keys
The output of KDF would be some pseudo-random bytes. For RSA, the bytes might not be a prime number. For elliptic curves, the bytes would likely not be a co-ordinate on the curve. Even ignoring that output is coming from a KDF I'm unclear on how ... |
Having a difficult time wrapping my head around the Blom's key distribution. I found an online resource to understand this but still couldn't get it.
I am attaching the screenshot from the book where the author first mentions the algorithm and then he solves an example .
A better explanation to the example how values a... |
I was experimenting with hashcat and aircrack to test WiFi security.
The WiFi AP is a WPA2 encrypted network. The tool I used to capture is bettercap, which captured multiple WPA2 handshakes.
The problem is that from those multiple handshakes I get two valid passwords for the same AP.
Question is, did I find a WPA2 has... |
If I understand correctly (please let me know if any of the following is wrong), a fully homomorphic encryption scheme $\mathcal{E}$ is such that for any messages $x, y$,
$$
\mathcal{E}(x + y) = \mathcal{E}(x) + \mathcal{E}(y) \\
\mathcal{E}(x y) = \mathcal{E}(x) \, \mathcal{E}(y),
$$
i.e $\mathcal{E}$ is a ring homomo... |
In the case of RSASSA-PKCS1-v1_5, is it simply that the cryptographic libraries and APIs are designed to only sign if determined superficially that it has a private key, or is the public key mathematically incapable of signing? Or perhaps in asking this way there is some major wrong assumption I'm making about keypair... |
I have been reading papers about authentication in VANETS and some of them mention a certificate that a trusted authority generates for a vehicle and has the following form:
$${C_{V_i}}=S_{TA}+H(PID_{V_i}|PID_{TA}|P_{TA}|P_{V_I})*x_i$$
Here $S_{TA}$ is a secret that belongs to Trusted Authority.
$H()$ is a hash functio... |
Background:
TEA uses a 128 bit master key $K_{0\ldots3}$. All odd rounds use $K_0$, $K_1$ as the round subkey, and all even rounds use $K_2$, $K_3$. One cycle of TEA applied to the block $A_i$,$B_i$ is: $A_{i+1} \leftarrow A_i + F_i(B_i, K_0, K_1) \hspace{0.5em};\hspace{0.5em} B_{i+1} \leftarrow B_i + F_i(A_i, K_2, K_3... |
I'm trying to implement a naive version of CKKS in Python.
It was great until I start implementing the modulus.
For this kind of schemes, the modulus $q$ is in the range $(-q/2,q/2]$.
How does this work?
In CKKS paper (I think BGV and others do the same) use something like this (a toy example): $c = m (mod$ $q)$. Where... |
In cryptography I am facing the issue to find a generator of some elliptic curve given only the curve over given field and number of elements that the curve has.
The numbers used are enormous so I am struggling to implement any offered scenario how to find generator of an elliptic curve here in stackexchange. If anyone... |
I have two questions I couldn't find straightforward answers to after many searches.
(1) We can perform 2-party MPC over arbitrary functions using Garbled Circuit. To do that, we first need to convert a function to a boolean circuit and then garble it. Is there any tool available where we can convert any arbitrary func... |
This function from Wikipedia calculates the sbox used in AES:
#include <stdint.h>
#define ROTL8(x,shift) ((uint8_t) ((x) << (shift)) | ((x) >> (8 - (shift))))
void initialize_aes_sbox(uint8_t sbox[256]) {
uint8_t p = 1, q = 1;
/* loop invariant: p * q == 1 in the Galois field */
do {
/* multi... |
After implementing and playing around with famous "Chosen Ciphertext Attacks Against Protocols Based on the RSA Encryption Standard PKCS #1" there couple of questions which I can't really grasp.
Why do we get intervals with their ends interchanged?
Why does it work to discard intervals in pairs?
Intervals Ends
I look... |
This is not a duplicate, I'm asking which method is better.
I generate an encoded argon2 hash string, so it'll be stored in database to verify login passwords.
Saved encoded hash has salt of length 16 bytes and tag with length of 32 bytes. I need to derive second different key from the saved key using two parameters:... |
Let $f \in \mathbb{Z}[x]$ be an irreducible polynomial of degree $N$ and $q \in \mathbb{N}$. Consider the rings $R := \mathbb{Z}[x]/f$ and $R_q := R/q$. Obviously, an element of $R_q$ can be represented by means of $\ell(N, q) := N\lceil\log_2(q)\rceil$ bits. In lattice-based cryptography the polynomial $f$ is often cy... |
This question is from Quadratic Sieve Factorization Method. Didn't find the solution on the web also. And not aware of how to solve such questions.
|
so I recently stumbled upon this video by @bertcmiller who created two transactions with the same nonce "k". That seen I researched quite a lot of pages explaining how to recover the private key from this. I know that I first have to find out the "k" value to recover the private key.
The formula for getting k is:
$k = ... |
Given a range of numbers, e.g. [1, 2^256], does each number have the same chances to be picked by a CSPRNG, which are 1 in 2^256?
My concern is that truly random number generators do have this feature, but it's not always secure in cryptography (I presume), because numbers such as 741 in such a large range that is [1, ... |
I'm looking into how authenticated encryption primitives work and was wondering if non-repudiation is provided with these. Investigating further into them led to the answer being that data origin authentication (DAO) are provided by the primitives.
Now DAO is defined as "the source of the information being verified", p... |
The following question is from Stanford cryptography course final exam paper.
Suppose an attacker intercepts a ciphertext $c$ which is the encryption of a message $m\in\{0,1\}^n$ under nonce-based counter mode. Can the attacker create the encryption of $m\operatorname{XOR}1^n$ just given $c$? If so, explain how. If no... |
The algorithm tells that, in the effort of solving $a^x \equiv b \text{ mod }N$:
Choose some $k \in \mathbb{N}$.
Create the baby list: $\{1,a,a^2,...,a^{k-1}\}$
Create the giant list: $\{ba^{-k},ba^{-2k},...,ba^{-rk}\}$ where $rk > N$.
Claim: If two lists have intersection, then this DLP has a solution.
$\textit{P... |
What's the difference between BLS12-381 and BLS12-377?
Previously I thought their basic cryptographic algorithms were same, so it's easy to construct BLS12-381 from BLS12-377, or construct BLS12-377 from BLS12-381, by just changing some curve parameters. Is this correct?
However, in some fields, such as ZK-proof, someo... |
From what I could gather, zero knowledge proof is a way for a prover to convince a verifer of possession of some data without sharing said data. I understood the ali baba cave problem. Diffie Hellman on the other hand seems to be a way for two people to create a shared secret key without explicitly divulging the key it... |
I'm very new to cryptography and am having some issues with the following question
A hash function H encrypts an n-block message m = (m1, m2 ... mn) in CBC mode:
- Block size is 128 bits
- Hash result is the last ciphertext
- IV is arbitrary 1 block long
- Encryption key is arbitrary number -> 128, 192 or 256 bits
- IV... |
What is the flaw of secret sharing? It seems that there is no mention in the literature of the defects of secret sharing, such as the defects of homomorphic encryption may be less efficient computing, what are the defects of secret sharing?
|
After reading "Verify the identity of sender" , which was part of an answer on StackOverflow, I was wondering if the following is possible:
Based on part II, if I am sitting between Alice and Bob:
Can I not wait for Alice to send her public key to Bob.
I block this key and discard it, and send my own public key instea... |
EDIT: The bounty is actually to draw more attention. I accidentally chose the wrong reason.
$E$ – Elliptic Curve over finite field $\mathbb F_p$.
Let $k$ be the embedding degree of the Curve with respect to a prime $q$: The full torsion group of all $q$-torsion points lies in $E(\mathbb F_{p^k})$.
For the MOV attac... |
Regev's Public Key Cryptosystem is defined as follows:
I want to proof the correctness. For this it must be shown that a 0 is decoded correctly and equally that a 1 is decoded correctly. I would present here once my proof:
Case: Encryption of 0
$$b = \sum_{i \in S} b_i = \sum_{i \in S} ( \langle \mathbf{a_i},\mathbf{... |
$$a_1*s+m_1+e_1 = b_1\\\cdots\\ a_n*s+m_n+e_n = b_n$$
The LWE problem is related to finding the solution $s$ to this system, when the $e$ are sampled from the normal distribution. Why the normal distribution?
|
For university I am doing a piece of coursework right now. This question is focusing on CPA and collisions using CPA.
Question:
I have attempted to answer part 3, but am not very confident in the answer. If anyone could please take the time to look at the question and look at my answer to let me know if I am going in ... |
Linked is a website that has a capture the flag problem with RSA: https://konsolas-2022-04-24.herokuapp.com/
I know very little about RSA decrypting but I do want to try and solve it, but I'm not sure where to start. I found https://www.tausquared.net/src/pages/ctf/rsa.html which would be useful if I knew the public ex... |
As AES could be considered as a function AES(key, data) that return encrypted data, is there a use of the construct of AES(key1, AES(key0, data)) as the resulting data could be decrypted by key2? Is there a way to determine key2, if key0 and key1 are known?
|
I'm trying to perform ECDSA verification in hardware. I'm using the SECT233R1 curve (NIST B-233). I have a question about the hash function used while doing so.
I want to use the SHA256 hash function while signing and verifying. In this case, the hash function will have a larger message length (256-bits) than the ellip... |
I have a course work for university, and am not sure on my answer so if anyone could please take the time out to read the question and my answer to let me know if I'm going in the right direction that would be greatly appreciated.
Question:
My answer:
For a block size of 1 there are no collisions possible using the ha... |
Is any concrete and real examples of CCA-attacks in recent history.
I'm aware about examples of WW2, but I'm more interested to modern examples in a digital context (for example against OFB, CBC).
|
In the usual definition of security for message authentication codes, we let an adversary $A$ have access to an oracle for $Mac_k(.)$. However, if we consider that there exists a more powerful type of adversary $B$, that is also able to query an oracle for $Vrfy_k(.)$, how can we redefine the notion of security?
|
Having just finished reading The Code Book by Simon Singh, which I found extremely illuminating, nevertheless I remain deeply puzzled about one aspect in the book regarding the one-time pad cipher. To cut to the chase, I don't understand how a would-be hacker would be able to break a given OTP cipher (thereby deriving ... |
I've found a post here: Small subgroup confinement attack on Diffie-Hellman
which says we can pick $k$ in this way:
And, as we know, $2$ will always be a prime-factor of $p−1$, therefore there will be a subgroup with two elements, that don’t generate anything besides themselves. Obviously the neutral element $1$ is in... |
I want to transform a semi random input to a shorter, uniformly random bit string. Assuming there is enough entropy in the semi random input, can I use a collision resistant hash function to extract randomness?
Update
After the first answer pointed out that the body of the question is not correctly asking the intended ... |
A JSON Web Token is supposed to have the following format:
token = encodeBase64(header) + '.' + encodeBase64(payload) + '.' + encodeBase64(signature)
When I use the jsonwebtoken node.js function to create a token:
jsonwebtoken.sign({username : "admin", password : "admin"}, publicKey, { algorithm:'HS256' });
It produc... |
Assume we want to transform semi-random $n$-bit inputs into shorter $k$-bit outputs computationally indistinguishable from uniformly random bit strings, and there is (in some sense, to be specified) enough entropy in each of the semi-random inputs towards this.
Under what condition(s) on a hash† function (and as far as... |
This question is related to this (but it is not the same).
Let's suppose I have a seed with an entropy of 1024-bits and hash it with a counter using a hash function with one-quarter of the seed size in bits as BLAKE2s (256-bits digest size).
I hash the seed with counters and XOR the result to plaintext.
As said in this... |
Let's suppose this:
Message is "I love crypto.stackexchange.com" (M)
Bob creates hash H1 with the message M and his private key (Priv)
Alice receives a message X, and hash H2 with message X and the public key of Bob (Pub)
So from 1=(,Priv) and 2=(,Pub) can we tell if =? (thanks to @fgrieu)
If it's not possible with a... |
Let's suppose :
I have a record/database (D) of 754 lines and each line correspond to a SHA256 hash.(Hn)
I hash all this record to a final and unique SHA256 hash like this : 1a3e6af379316c6b863318f9e23ad0588d7d845ea92f316779f36167fd359fb0 (F)
I know H34 (single entry of D) which is 9370d1f5ab2fe94f685039fc8a2bb8ec3c2a... |
Let $H: X \rightarrow \{0, 1\}^b$ denote a cryptographically secure, $b$-bits hash function on a set $X$. Let $H^*: \mathbb{P}(X) \rightarrow \{0, 1\}^b$ be a function on the power set of $X$ defined by
\begin{equation}
H^*(\{x_1, \ldots, x_n\}) = \sum_i H(x_i)
\end{equation}
where the sum is intended as wrapping addit... |
If two ensembles are statistically indistinguishable, we all know that they are also computationally indistinguishable, i.e., for any PPT algorithm, the probability to distinguish them is negligible.
My question is, what if the algorithm is not polynomial-time, but time-unbounded?
|
First of all, I am a student, so even if most of you think it is a useless question, don't dishearten me as it is a platform for me to learn
I am using an AES code that has 3 Rows and 4 columns in its Shift Rows. Although I know in AES we have 4 rows and 4 column block. Then why is it working, I am not able to understa... |
Suppose we have the description of a group $\mathbb{G}$, a group of unknown order: the size of the group is unknown. For instance, an RSA group ($\mathbb{Z}^{*}_N,$ where $N=pq$ for unknown primes $p$ and $q$) or a class group. The prover wants to convince the verifier that for $h=g^x$ and that the exponent is non-nega... |
GMW is a pretty straight forward protocol for the setting of 2PC. It is still straight forward for the case of MPC except for the AND gate. I'm struggling to understand how to obtain a "good" communication complexity. To be more specific, the AND gate is described by the following function.
\begin{aligned}
c &=a \w... |
Let $n = P\cdot Q$ be the product of two safe primes $P = 2p+1$ and $Q=2q+1$.
Let $g$ be a generator of $C_{p} \subset \mathbb{Z}_n^*$, the multiplicative subgroup of order $p$. In other words, $g^p = 1 \pmod n$. (But $p$ is still secret of course.)
Would it weaken a RSA modulus if $g$ was public? It is easy to compute... |
I searched a lot for this information in search engines as well as taking a look in the SHAKE reference implementation.
If I decide to use SHAKE as a stream cipher, can I access a specific part of the keystream without having to generate previous data from the beginning?
|
I read a website on The Pohlig-Hellman Algorithm for solving the DLP, in which it states that we can express $x$ as:
$x= a_0 + a_1p+ a_2p^2+...+ a_{e-1}p^{e-1}$, where $p^e$ is a prime factor of the order of the group.
We then can brute force all of $a_i$'s.
But my question is, if we can figure out all $a_i$'s, why we ... |
I was reading the Wikipedia page for SHA-256 (SHA-2) and came across the following statement:
For a hash function for which $L$ is the number of bits in the message digest, finding a message that corresponds to a given message digest can always be done using a brute force search in $2^L$ evaluations.
Why is this true... |
I am trying to closely follow the algorithm here (keeping the same variable names) and reconstruct the cryptosystem in Sage Math engine. It seems to work on parameters (N, p, q) = (11, 3, 31) but raises assertion error at the end on (N, p, q) = (11, 3, 29). Please see the code below:
N = 11
p = 3
q = 31 # fails for 29
... |
I'm trying to get my head around this scenario. I understand that a private key can be used for signing a message to provide authentication and public key can be used for encrypting and its corresponding private key can be used to decrypt it. I came across this scenario and Ive been trying to research why this scenario... |
Hashing a seed with SHAKE-256 and setting the output size to 1GiB it takes 6.5 seconds on my system:
$ time dd if=/dev/random count=40960 bs=1 &>/dev/null | shake256sum -N 8589934592 > /dev/null
real 0m6.497s
user 0m5.682s
sys 0m0.844s
/\ 165.2 MiB/s
SHAKE-256 can be used to generate keys of any size as an (exp... |
Let's suppose I have a 1MB high-resolution photo and I want to hash and create a 1536-bits key.
I know that I could just use SHAKE-256 as its a pre-enginered way for doing that.
There is also Skein that can emit outputs of any sizes (up to 2^64-1).
But Skein has a internal state of 1024-bits.
If I decide to use Skein t... |
It's given 2 plaintexts $m_1$ and $m_2$, and 5 different values of $n\quad\{n_1, n_2, n_3, n_4, n_5\}$ which are generated as follows:
$n_1$ is a a product of two relatively small 128-bit $p$ and $q$ so its easily factorable by a simple database look-up,
$n_2$ is the value of $p_1*p_2*q_1*q_2$, with $p_2$ being the ne... |
A cryptography course covered among others following questions:
arithmetic of polynomials over $GF(2^m)$ fields - polynomials division
elliptic curves over field $GF(2^m)$
In scope of former point students were told polynomials product needs subsequent division by irreducible polynomial in order to stay in given orde... |
I am making a program that verifies the avalanche effect for the SBOX of the AES block cipher for a certain number of iterations. This program changed one bit randomly in one of the elements of the input list (state) and then applied the subBytes operation to both the original and modified lists. After that, it counts ... |
I'm going to guess the latter, but just wanted to ask here.
I want to have a relatively short signature, and my goal is to take a substring of the resulting hash.
|
In ZCash, Monero etc, the sender/receiver addresses as well as transaction details are hidden. However, with a viewing key, a third party can see the exact details of the transaction or all transactions done by a certain address. How are things like these achieved? Any direction or sources are appreciated.
|
Let's say I have a 32-bit number and a primary secret key and want to encrypt it without increasing the size.
this is how I'm doing the encryption,
I create an HMAC hash using the primary key and current date as data
Then XOR input bytes with hash bytes a few times
for (let offset = 0; offset < hash.length - 4; offse... |
When I read the work of Dodis et al. ref1, it looks as if I have encountered a simple logical bug. (I'm not concerned with the details of secure proof techniques, but with the logic of reasoning.)
In this article, Dodis et al. demonstrate the one-way security of ROM-AI (ROM with auxiliary information). The core idea is... |
I am following the NTRUEncrypt cryptosystem as described on the wikipedia. I have implemented it in Sage Math engine (with small problems along the way, but in the end - succesfully resolved) and the system works just as expected.
I have noticed an interesting publication regarding expanding NTRU to higher order algebr... |
There seem to be two ways to RSA-encrypt using .Net:
EncryptValue (which doesn't seem to pad the plaintext).
and
Encrypt (which does).
I was wondering, since what I'm encrypting is a cryptographically secure (cough...) AES key, do I need it to be padded by an official padding scheme? Assuming, of course, that the lengt... |
Let's suppose I want to encrypt a 10GiB file but I don't want to use a One Time Pad, just a 1MiB key taken from /dev/random (in Linux).
I know that the key should not be repeated, but is it possible to do a form of pseudo-OTP by using the same key across the entire plaintext?
I thought in a scheme: Hash each 64-byte pi... |
If I encrypt a 1MiB file with AES-CBC (or any other cipher) and XOR a 128KiB of (truly) unpredictable random data repeating until the end of file, will I have a security of 1048576-bits (128KiB*8)?
This question is a little weird, but I would like to know if this scheme has a security flaw (maybe known-plaintext attack... |
I'm trying to understand the implication of the Binder Keys in in a TLS 1.3 resumed handshake. The TLS 1.3 RFC provides an additional RFC with example traces to validate all the math in a TLS 1.3 handshake. I'm using this example trace to try to re-create the binder keys to understand what went into them.
One of the e... |
In BLAKE2X paper it is said:
BLAKE2X adds a constant overhead of $\lceil\ell/64\rceil$ (resp. $\lceil\ell/32\rceil$ compression function calls compared to the underlying 64-bit (resp. 32-bit) BLAKE2 hash. For example, to compute a 1056-bit (132-byte) hash as required in Ed521 signatures, BLAKE2X adds† $\lceil132/64\rc... |
Can a file encrypted with a hashing algorithm (like SHA-256) be equally secure as a symmetrical algorithm (like AES)?
This is how it could be done using a password (this is the most simple example, please don't suggest optimizations, it's just the concept):
Generate random looking binary data of the same length as the... |
In this journal paper related to physically unclonable function (PUF) [1], the authors used NIST 800-22 test to check if the bitstreams generated by their PUFs are random, which is described as follows:
NIST tests are performed using 60 sequences of 128 bits each such that 7680 bits (i.e., digitized keys) collected fro... |
I understand that it is easy to compute eth root in Z(P)* but what about with Z(N)? I know that it requires the factorization of N but what does that actually mean? What is an example of calculating the eth root in the set Z(N) (the set of all elements coprime to N)
|
I was looking at the archives for the British national cipher challenge, and a modified version of an ADFGVX cipher came up twice (2003 2011), with block transposition instead of columnar transposition.
The question I has is what is this referring to? I tried finding information about block transposition, but there app... |
Are there examples (in code, or a blog post / writeup) of using Noise and Signal together?
Here is a link to Noise.
For example, using the Double Ratchet per each message to achieve forward secrecy, but leveraging Noise as a foundation for its patterns of initial key exchange. Both Noise and Signal are well-studied and... |
I have 3 Pailler encryption p1=E(x1;r1),p2=E(x2;r2);p3=E(x3;r3) such that
x1*x2(mod n)=x3. P(Prover) knows (x1,r1);(x2,r2);(x3,r3).
Can I design a ZKP(interactive & non-interactive) for P to convince V(verifier) that values hidden by p1,p2,p3 satisfy x1*x2(mod n)=x3.
|
I can generate a key of any security in bits with any hash function from random source with enough entropy by using the following scheme:
$$H(00||S) || H(01||S) || H(02||S) || H(03||S) || \cdots$$
/\ H is the hash, S the seed and 00, 01, 02 the counters.
BLAKE2X hashes are computed as follows:
$$\operatorname{B2}(0,64,... |
I am a Bitcoin enthusiast, but I have never been formally trained in the study of computer science and cryptography.
Recently, I tried a new way to encrypt my private key: I wrote it down on a paper, and used my camera to take a photo of that paper sheet. Then, I encrypted the photo from pgp4win.
Then I noticed that th... |
The title is a mouthful, allow me to explain my situation.
I have a SaaS with many users.
When new users join the platform, I want to create a cryptographic keypair for them (Ed25519).
But I don't want to have any knowledge about their private key.
This means the keypair must be generated and stored by a third-party s... |
I have some doubts regarding AES weakness and AES cryptanalysis. While it is relatively simple to find Cryptanalysis info on previous ciphers, I get confused about understanding various types of Cryptanalysis attacks on AES.
So far, for example, I've found that AES's weakness could be in its algebraic structure. Anyone... |
If an attacker has a database of 1,000 users' hashed passwords which are hashed with SHA-256 with a 128-bit salt and all of these users used 10,000 common passwords. How many hashes will the hacker need to do to recover all passwords?
I was thinking it would just be 1,000*10,000 = 10,000,000 hashes but I am not sure ho... |
Is there any PKE scheme that is IND-CPA secure (in a standard model, not RO) under a search problem?
|
I have been reading about Zero Knowledge Proof (ZKP) protocols for a while now. Among the applications I have seen the most is authentication (https://ethereum.org/en/zero-knowledge-proofs/#authentication). But in practice it is not used; why?
I have also been looking for why these protocols are not used in authenticat... |
I'm protecting communication between some microservices using public/private key encryption, where the sending container has a public key and the receiving container has a private key. This both verifies the sender (only sender has the public key via a credential manager), and protects the data in case it may be buffer... |
I'm trying to implement the 1st round attack on RC4 stream cipher according to Attacks on the RC4 stream cipher. For now I am interested in section 4.2 Attack on other key bytes. It works really fine for all the bytes of the random key of length 8, except the 2nd byte. The needed value t is always the second frequent o... |
I know restricting access of a file, is a important measure of security.
If we read the Payment Card Industry's Data Security Standard (aka PCI-DSS), we can see a requirement where control access must be applied to mitigate any risk of a sensitive encrypted data be leaked from the system.
Other important requirement de... |
I've been reading for Pohlig-Hellman Algorithm on Elliptic Curve.
My question is, why the simultaneous congruence gives the answer we want, could somebody please provide a proof of it?
i.e., why
\begin{align*}
x \equiv x_i \mod p_i^{e_i}, \forall i\in \{1,2,...,n\}
\end{align*}
Reference: https://risencrypto.github.io/... |
If the Substitution box is 1 to 1 (a specific value can only ever be a specific box value), and the contents of Rijndael S-box is public, how does this offer any additional security?
With AES the frequency of a letter isn't a concern so what other reason is there for this substitution? An explanation fitting for a novi... |
I'm reading headlines on the tune of "…bring zero-knowledge encryption to file storage". Googling "zero-knowledge encryption" returns statements like "cloud storage or backup providers know nothing (i.e. have “zero-knowledge”) about the data you store on their servers".
Is there some academic definition of "zero-knowle... |
I ask because some vendors of HSM try to avoid the export of wrapped secret key from HSM to insecure storage – storage that does not belong to these vendor’s HSM infrastructure.
For example, Thales prefer to backup keys to another Thales HSM – most of their documentation is about cloning between their devices.
But Tha... |
We know that SHA-1 is susceptible to collision attacks, but what about pre-image attacks such as poisoning torrents?
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I want to prove that for every pseudorandom function $F: \{0, 1\}^n \times \{0, 1\}^n \rightarrow \{0, 1\}^n$ and for every polynomial $p$ such that $p(n) > 1$ for every $n$ it is possible to construct, starting from $F$, a pseudorandom generator $G$ having expansion factor equal to $l(n) = p(n) \cdot n$.
I fixed a PRF... |
I want to compute the multiplicative inverse of 0x2 over $GF(2^{233})$ in hardware.
To do so, I compute $a^{-1} = (a^{2^{m-1}-1})^{2}$. Here's the result of that computation:
0x10000000000000000000000000000000000000002000000000000000000 (where the left-most 1 is bit index 233, not 232).
I verify that I get 1 by multipl... |
I implemented the Pohlig-Hellman algorithm for the general case following Wikipedia but it only seem to work for prime powers (which is what the limited case is meant to solve).
My implementation follows wikipedia exactly: https://gist.github.com/nickponline/2ef6f3456ed6c423239a334c98728324
Some examples where it fails... |
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