instruction stringlengths 32 27.2k |
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In lots of cryptoanalytic papers I read, attack complexities are stated in the form of a constant. For example, this related key attack on of AES states:
[...] For AES-256 we show the first key recovery attack that works for
all the keys and has $2^{99.5}$ time and data complexity
I have seen this notation of $2^{n}$... |
I am having a hard time understanding what I have come across using RSA-textbook.
So I have:
e = 3 as an exponent
a VERY long public key N of 1991 bits (clearly useless trying to factor)
a very short cryptogram of 403 bits
By doing C^(1/3) (because we have a short message compared to the public key), I found the mess... |
I am a MPC learner for privacy-preserving machine learning. Recently, I am reading this paper: FLASH: Fast and Robust Framework for Privacy-preserving Machine Learning. I am confused about the question that why we need broadcast channel in the 3PC setting. I guess that is because consensus, but I am not sure. Can you h... |
i would like to know what are the danger can be occur by performing steganography without a key? Please kindly explain to me.
|
For a binary-circuit-based MPC, the multiparty will provide its inputs to calculate the result, which indicated the function $f(x_1, x_2, \dots,x_n)$ needs to accept $2$ or more inputs.
Why do there exist circuits e.g, SHA-$256$, which takes only one
input?
When I check the SHA-256.txt files, it takes $2$ inputs... |
I'm implementing Pedersen commitment scheme in order to enhance entropy of a pre-image of a hash. I'm using secp256k1 for my curve parameters.
I am following naming conventions from here:
What is a Pedersen commitment?
I am performing a commit $C = (m, r)$ and then another commit $C' = (m, r')$
Then I do the blind equa... |
After a bit of research, I finally understand what's the step by step algorithm of SHA-2 (however, of course, I won't remember it myself).
But I don't understand what's the idea behind it. Did the group of the algorithm's developers just randomly pick some constants and functions and apply them to the data and these co... |
I'm having a hard time understanding the usefulness of using an ECDH over traditional asymmetric encryption. Both parties have to exchange public keys to compute the ECDH, so why wouldn't they just encrypt their messages with the public keys they just exchanged?
The only use case for ECDH I can think of is if Alice los... |
I'm designing a program that clients can download to the computer. This program needs to sync with my online server on a regular basis to confirm that the client's Activation Code hasnt expired and they're paying their bills. However, I want the program to be able to run for a period of up to 5 days without having to c... |
Let $X$ be a measurable space. For each $n\in\mathbb N$, let $P_n$ and $Q_n$ be probabilities on $X$. We say that $(P_n)_{n\in\mathbb N}$ and $(Q_n)_{n\in\mathbb N}$ are statistically indistinguishable iff for all measurable set $E\subseteq X$, the function
\begin{equation}
n\mapsto |P_n(E) - Q_n(E)|
\end{equation}... |
Background. In their paper about the cryptographic scheme NORX, the authors use a fast approximation of + by bitwise operations (taking fewer CPU cycles than proper addition) using the formula $$a+b \; \approx \; a \oplus b \oplus ((a \land b) \ll 1)$$ where $\oplus$ is bitwise XOR and $\land$ is bitwise AND, and $\ll$... |
For example: "I am a very secret person".
I'd like to show someone that this string includes 'secret' without revealing the rest of the string. Is there anyway?
|
I think one of them is related to multitarget attacks and the other is related to collision attacks. But I cannot find how hash based crypto related to hash collisions.
1-) Consider the following Lamport one time signature scheme
Assume a 128 bit hash function $H$ is used
Randomly choose $p_i$ and $r_i $ for $1\leq i... |
In a group signature scheme based on Pointcheval-Sanders (PS) single-message signature, the anonymous credential $(\sigma_1,\sigma_2)$ issued by the group manager (GM) with secret key $sk = (x,y) \in \mathbb{Z}_p^2$ and public key $pk = (\tilde X,\tilde Y) \leftarrow (\tilde g^x,\tilde g ^y )$ to a user $\mathcal{U}_i$... |
I have logs containing sensitive data (mail addresses, usernames etc.) that need not only be made GDPR compliant, but in general be secured as best as possible, so anonymization/hashing would be an easy solution.
However, at the same time I need to be able to correlate the information for monitoring purposes (e.g. iden... |
I'm wondering since at least 2 offline password management services,Passkeep and Keepass both use biometric authentication in addition to the master password. You need to possess the physical device to login to those 2 services,but if the attacker already posseses the device how would biometric authentication protect t... |
I am currently new to the world of BLE and I came across this article which mentions ECDH.
In the diagram in part $3$, it generates the DHKey/shared secret (I am assuming this is the correct terminology based on google search) , but then once it's generated the diagram never references it ever again. What exactly is th... |
While having a discussion with someone on a forum about GPS spoofing, he mentioned that GPS signal can be spoofed for a cruising missile and make it land somewhere else using side-channel attack along with cryptographic accelerator. Now, from all that I could gather about side-channel attack and cryptographic accelerat... |
I am looking for the definition of the strong Diffie Hellmann problem. However, I can only find definitions for the $\ell$ or $q$-strong Diffie Hellmann.
Is it possible that the strong Diffie Hellman problem is also called the $\ell$ or $q$-strong Diffie Hellmann problem?
|
I am on the abbreviation mutlin. DDH, which probably stands for mutliniear Decision Diffie Hellmann. I am currently looking for a definition for this term, but unfortunately cannot find a source. Can anyone here help me further?
|
I am currently in the process of understanding ring signatures.
Now I have arrived at Linkable/Tracable Ring Signatures, however I don't really understand them.
Can someone explain me how the principle behind it works?
An example would also be very helpful.
Thank you very much!
|
If you encrypt with:
gpg -o gpg.symmetric.test.gpg --symmetric gpg.symmetric.test
and then decrypt with:
gpg -o gpg.symmetric.test1 --decrypt gpg.symmetric.test.gpg # --decrypt option mistakenly included
the output gives:
gpg: AES256.CFB encrypted data
gpg: encrypted with 1 passphrase
and decrypts the file WITHO... |
The cipher is a modification to AES and is described on this website:
The only difference between Jipsam1 and AES-256 is the S-box. Whereas in AES the S-box is public and constant, namely
$$
\begin{pmatrix}
1&0&0&0&1&1&1&1\\
1&1&0&0&0&1&1&1\\
1&1&1&0&0&0&1&1\\
1&1&1&1&0&0&0&1\\
1&1&1&1&1&0&0&0\\
0&1&1&1&1&1&0&0\\
0&0&... |
I'm new to cryptanalysis and I saw in another answer to a question that $f: \lbrace0, 1\rbrace^{\kappa}\to \lbrace0, 1\rbrace^{\kappa}, f(x) = 1^{\kappa} $ is a one way function. Why is this the case? Any help would be appreciated
|
ESN feature is described in RFC 4303. Here is some questions which bothered me:
When use ESN combined with AES_GCM or AES_GMAC alogrithom, do I need to add the high-order ESN bits to the packets?
According to RFC 4303: If a combined mode algorithm is employed, the algorithm choice determines whether the high-order ES... |
This post asks if a user of a system can restrict their own access in a time-related way.
I am interested in this for freezing and unfreezing cryptocurrency accounts to enforce spending controls, but I am really interested in learning about it as a general class of problems. I wonder if it hasn’t been studied since the... |
I've got a situation where I need to send message ciphered with AES-256. However the content, and therefore length, of the message may be intercepted before (don't ask;)) and the question I was asked was "isn't a vulnerability allowing to discover the key?". My first approach was to estimate the brute force needed to c... |
I tried to search and take a look at a way to securely generate or import secret keys on client-side. First I tried to see if it is possible to take advantage of TPM in Windows but as far as I understood it is not possible to use it. So as far as I got the correct way to deal with encryption keys was using Web Crypto A... |
I'm now trying to design a more secure key-change algorithm to replace widely used DH.
However, I am only able to prove that my algorithm is more secure logically, which means I can only prove it from a reasoning rather than mathematical perspective.
Thus I wonder if there is a standardized procedure that I can use to ... |
No matter AES with CBC or EBC etc, the inputs for AES i.e, plaintext, key, IV, are always provided by one party. In other words, there is no need for AES in a 2PC scenario since one party can already calculate and get the result.
When I check e.g. the AES-no-expanded.txt files, party one has 128 bits input and party tw... |
My knowledge of cryptography is beyond shallow, and I have a problem I cannot solve.
Trezor wallets have two message signing formats: "Trezor" and "Electrum".
I have a method in my code, that is retrieving the public key from messages signed using BTC wallets (i am using bitcoinj library):
public VerificationStatus ver... |
I'm replicating an invalid point attack on ECC using Short Weierstrass curves. For this I have written a "dumb" implementation that does not validate points are on the curve before going into the scalar multiplication. For the outline of the attack, I'm heavily borrowing from Samuel Neves' excellent descrption which he... |
Looking at the example of the null input (512 bits), it takes as input:
input (Hex):
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
Since it's exactly 512 bits, there is no splitting and no padding. But from online calculators or golang... |
I am trying to identify how the SP Network is constructed. I am looking for plausible solutions that help to connect these layers together and what are the ways that exist in literature other than Kam and Davida and The wide trail strategy of AES that can help in creation of a secure SP network.
|
Does the following checksum function make sense?
I am attempting to show that for all even numbers there exists at least two summands that, when normalized to $\frac{1}{2}$, asymptotically sum to 1:
$\lim \limits_{n \to \infty}\frac{n-1}{2[a+
\varphi(a)]}+\frac{n-1}{2[b+\varphi(b)]}\sim
\frac{n}{n}=1$
where $n$ are eve... |
In the process of studying discrete logarithms and approaches that could be taken, I saw the Pohlig-Hellman algorithm.
Later when I was working with $h = g^x \mod p$ where $p-1$ is smooth, using Pohlig-Hellman did not give the expected result, and returned something much larger than expected. I assume this is because P... |
Has the following method of hiding data been proposed or studied? What is the efficiency or security of this method? What applications could use this method?
Data is to be hidden in a number that is the product of two prime numbers.
One prime number contains the hidden data, and a bigger
prime number indicates the leng... |
About birthday attack,
book Cryptography Engineering says:
In general, if an element can take on N different values, then you can
expect the first collision after choosing about $\sqrt{N}$ random
elements. We're leaving out the exact details here, but $\sqrt{N}$ is
fairly close. For the birthday paradox, we have N = 3... |
Are there any cryptographic methods $f,g,h$ which can be applied in any order to an input $x$ while still resulting in the same result $r$:
$$f(g(h(x)))=h(g(f(x)))=ghf(x)=fhg(x)=hfg(x)=gfh(x) = r$$
Same for their inverse function:
$$f^{-1}(g^{-1}(h^{-1}(r)))=h^{-1}(g^{-1}(f^{-1}(r)))=g^{-1}(h^{-1}(f^{-1}(r))) =...= x$$... |
In Cryptography Engineering:
2.7.1 Birthday Attacks
Birthday attacks are named after the birthday paradox. If you have 23
people in a room, the chance that two of them will have the same
birthday exceeds 50%. That is a surprisingly large probability, given
that there are 365 possible birthdays.
So what is a birthday a... |
I encrypted some data (an incredibly long time ago). I have both p,q,n,c, and a plaintext ciphertext pair (from when I encrypted the wrong data). I took to solving the discrete logarithms required here, and ended up with solutions to both of them using Baby Step Giant Step. I recovered e (e1) and tested using assert po... |
I'm learning the randomness test of the NIST SP 800-22 rev 1a documentation.
https://csrc.nist.gov/publications/detail/sp/800-22/rev-1a/final
As I was reading, a few questions came up and I put them up like this.
My questions are:
In the Frequency Test within a Block of 2.2, looking at (3) of 2.2.4,
there is a part th... |
(this might be a silly question)
Pedersen hash works in the following way: $(x, y) = kG$ where $k$ is the pre-image and $(x, y)$ is the resulting hash.
Say we hide part of the hash to preserve privacy. Can an attacker derive $y$ if they only know $x$ given that they don't know the pre-image?
In other words, by knowing ... |
I want to implement TOTP in the same manner as RFC 6238 (https://www.rfc-editor.org/info/rfc6238), but keccak instead of SHA-1.
Keccak follows sponge function with the data rate r and the capacity c.
For lightweight version, the combination of (r,c) may (72,128).
Let's assume that the bitwidth of time is r and the bitw... |
The RSA-Assumption says that $(GenSP,F,SampleX)$ is one-way. So if we initialize an instance of RSA $(n,e), (n,d)$ and fairly forget the secret-key and SampleX uniformly distributed over $X, F = x^e \bmod N$ should be one-way.
Now it is also known that Injective functions imply collision resistance, but not one-way of ... |
Given a number $N$ with $d$ unique prime factors. Can the number of unique values $v$ with
$$v \equiv x^d \mod N$$
$$x\in[0,N-1]$$
$$N = \prod_{i=1}^{d} p_i$$
be calculated for $d>2$? (Q1)
Does the total amount decrease at some point? (Q2)
For simplification we assume each prime factor $p_i > 5$.
Or for target use c... |
If such throughput could be achieved what would the benefits for a data center or IoT devices in terms of power saving. Also I was wondering if such speed was possible to be realized by a cipher, would that dramatically change cryptography in terms of encryption/decryption speed? If that is possible in the future, woul... |
Is there any reason why collision resistant variants of ed25519 that use a single-pass aren't used instead? For example:
$n = h(noncekey \| m)$
$h(R \| pub \| n)$ instead of $h(R \| pub \| m)$
or alternatively if we want to not change the EdDSA algorithm itself and instead implement collision resistance on top of it:
L... |
SHAKE256_XOF is an extendable output function based on SHA3-512. SHAKE256_XOF can be used to create an infinite length bit string with 256-bits of security. For example:
from Crypto.Hash.SHAKE256 import SHAKE256_XOF
shake = SHAKE256_XOF()
shake.update(b'key' + b'nonce')
for _ in range(10):
print(shake.read(16).he... |
Let's say we choose AES as cryptographic algorithm for IPsec.
My question is the following
Is the key produced by Diffie-Hellman algorithm used as INPUT to the AES
algorithm so AES does the encryption with it?
|
I have been attempting to analyse the classic proof presented by Barak et al. that claims Black-Box Obfuscation is not possible for (what appears to be) most classes of programs.
The proof is presented in such a manner where it is said that if there exists an encrypted program C'(a, b, x) which returns b if and only if... |
I am trying to accomplish the following:
$Alice$ is an authority that can provide a secret $x$ to $Bob$, $x$ will enable $Bob$ to generate a public/private key pair $(p,q)$ which he can then use to sign messages. $Alice$ will not be able to sign messages as $Bob$.
Anyone can trivially verify that the public key $Bob$... |
I would like to encrypt cryptocurrency wallet seeds (12 to 24-word passphrases) for replication and secure preservation. The seeds would be in a .txt or .rtf format before encryption. I would like to be able to send these over the internet with peace of mind. Encryption should hold for at the very least 60 years. What ... |
I was reading this paper on RC6 and formally, the algorithm is defined for an arbitrary word size $w$, even though only $w=32$ was considered for the AES submission. Now the paper explicitly mentions the choice $w=24$, among others. Later on in the paper, it says:
"The base-two logarithm of $w$ will be denoted by $\op... |
I want to encrypt a system firmware, and future firmware updates will use the same encryption system. Because this firmware isn't fully from scratch but rather is based on an existing framework, it is highly likely that parts of the original firmware code are known, in other words, that long sequences of the message to... |
After reading "Can the xor of two RNG outputs ever be less secure than one of them?" I wondered if you can increase security of SHAKE256_XOF by using another instance of the CSRNG. The theoretical security of SHAKE256_XOF is 256 bits. After a theoretical quantum attack it has min(key_length/2, 256) bit security. So u... |
Similar to this question, but having two seperate inputs for each length preserving one way function $f$ and $g$, i.e. $h: \lbrace 0,1 \rbrace^{2\kappa} \to \lbrace 0,1 \rbrace^{2\kappa}, h(x) = f(x_1)||g(x_2)$ where $x_1$ and $x_2$ are two $\kappa$ bit split halves of x.
I think $h$ will be one way, but am not sure on... |
I was just wondering how the private key generator should publish the master public key inside of an IBE system. This key is needed for all devices in the network to derive the public key of receiving entities.
|
The impossibility of a secure "blind HMAC" scheme - an HMAC-based analogue of blind signatures - is known (as I understand it, essentially due to the user being unable to validate the signature received against a public key for the signer, and therefore being unable to be sure the signer is not using many signing keys ... |
Let's suppose I want to modify Kuznyechik block cipher by choosing a random S-box (taken from /dev/random for example).
How can I calculate/generate the inverse S-box?
Does anyone know the formula or algorithm used to do this?
|
If I download https://example.com/foo.txt, how can I prove to a third party that I got it from https://example.com.
I understand that their private key is used to secure the channel, rather than to sign the content of URLs.
Is there a way of downloading https://example.com/foo.txt and providing a chain of proof that my... |
The company I work for wants me to implement some C functions to automatically sign their software. After doing some research I've found that openSSL is great for doing so.
Before starting the implementation in C, I wanted to get a feeling of the workflow by executing it in the CLI first. But that left me a bit confuse... |
I'm having difficulty finding a detailed proof for one of the most basic protocols in cryptography, that is the Schnorr protocol, or the sigma protocol for proving knowledge of a discrete log.
Most proofs I can find gloss over the running time of the extractor, or just assume the prover works with probability 1. But th... |
I need to sign a message using a private key and verify the message with a public key, while making sure the message hasn’t been tampered.
I know that SHA-256 itself is prone to length-extension attacks.
I also know that things like HMAC have been specifically designed to circumvent such attacks.
But what if I sign a m... |
So for my diploma thesis I'm writing about Regev's LWE cryptosystem from his original 2005 paper. I'm done with with correctness and security (only reduction from LWE-search via average-to-worst and decision-to-search reductions, however the main point of that paper - GapSVP to LWE-search reduction is outside of scope ... |
According to RFC4880 standard
1.Refer to section 2.1 Confidentiality via Encryption --> OpenPGP combines symmetric-key encryption and public-key encryption to provide confidentiality
+To protect the session key --> encrypted with the receiver’s public key
+To decrypt session key --> use receiver’s private key
2.Refer t... |
Assume elliptic curve in Weierstrass form.
$y^2 = x^3 + a x + b$ where $x,y,a,b \in F$
I noticed the point addition formula does not involve parameters $a,b$.
Furthermore, one can always solve for $a,b$ given two distinct points.
Thus one can "add" 3 or more distinct points, as long as their coordinates are on $F$, wit... |
Let's say that we have a classic RSA encryption, with n = p*q. For a given C, I saw on internet the RSA might be weak if we know that the plaintext M and n have a common factor. However, I wasn't able to find a proof of that.
We know that $M=C^e \space mod\;n$, with e being the public key. I tried to say that $M = a + ... |
Let $(Enc, Dec)$ be an IND-CPA secure encryption scheme, where $Enc: \mathcal{K} \times \mathcal{M}_1 \rightarrow \mathcal{C}_1$, and $F: \mathcal{K} \times \mathcal{M}_2 \rightarrow \mathcal{C}_2$ be a pseudorandom function.
Consider a simple example where we may want to prove the distribution $(Enc_k(m_1), F_k(m_2))$... |
Proof of Elapsed Time (PoET) was discovered by Intel in 2016 as a consensus mechanism primarily for permissioned blockchain networks. Importantly, we can only use this concept in permissioned blockchain, not public or private.
I think it is better than all other consensus algorithms as all miners are treated equally he... |
I've recently tried to replicate the results of the question Ruggero asked and which Samuel Neves answered here: Understanding Twist Security with respect to short Weierstrass curves
In my attempt to replicate this, I found that the attack does not work for some points. Initially my assumption was that this was because... |
Which impact on security (factorization) has a common prime factor among the prime factors $P$,$Q$ of a number $N$
$$N=P\cdot Q$$
$$P=2\cdot F\cdot p+1$$
$$Q=2\cdot F\cdot q+1$$
with $F,q,p$ different primes and $F$ the biggest prime factor of $P$ and $Q$ with
$$F\gg p,q$$
A potential adversary who want to factorize $... |
In Katz's Introduction to Modern Cryptography,
Chapter 7 Practical Constructions of Symmetric-Key Primitives
In previous chapters we have demonstrated how secure encryption
schemes and message authentication codes can be constructed from
cryptographic primitives such as pseudorandom generators (aka stream
ciphers), ps... |
A client has requested us to setup SSL certificate public key pinning for an internal desktop application we are developing for them. They have requested us to pin a specific pubkey but we are not aware of what format it is in.
The pubkey provided is WY*Nhx$kk@PTTz7Ykp*t!q#*8taRR84ZnyT7Rjqc%^29!7zx5GdYa!HSmpM^KQ!D. Any... |
Is there a standard way to generate ID numbers one after the other such that:
You can guarantee, or almost guarantee, that you avoid collisions. (By "almost guarantee", I mean for example if you generated completely random 24-digit numbers, and you "only" generated 1 million of them, then even with the birthday parad... |
For generator $g$ of order $n$ the group elements $y=g^x$mod $n$ are uniformly distributed because of the modulo operation.
Suppose however that from the original output space $Y$, we only consider those elements $y$ which have some bits "fixed" in their binary representation. For example, for $y = y_1,y_2...y_m$ (wher... |
Given a number $N$ with
$$N=Q\cdot R$$
$$Q=2\cdot q_1 \cdot q_2+1$$
$$R=2\cdot r_1\cdot r_2+1$$
with different primes $P,Q,q_1,q_2,r_1,r_2$.
If we now choose an exponent $\alpha$ containing prime factors of $Q,R$ with
$$\alpha=2 \cdot q_2 \cdot r_2$$
we can generate a sequence $S$ with elements
$$s_{i+1} = s_i^\alpha \... |
Before you ask, this is neither for a CTF or homework, this is on problems in implementing non-standard RSA. If it feels like it is a CTF problem I will remove this post if necessary.
Murru Saettone RSA is a variant and quite vulnerable (to a continued fraction attack) RSA scheme based on the cubic pell equation. When ... |
If I understand correctly, the way DSA in a group $G$ with a hash function $H$ works is: Peggy (signer) has a private/public key pair $x$, $g^x$. For signing, she produces a random session key $k$, $g^k$ then computes the signature: $s=\frac{H(m)+xF(g^k)}{k}$ where F is some "reasonably uniform function" $F: G \rightar... |
I need to implement following operation:
w = (z mod (n-1)) + 1
where
z: 40-byte array
n: the order n of base point defined for NIST P-256.
I assume that resulted 'w' could be a point on the curve.
Any opinions are more than welcome
|
It is known that we can transfer an ECDLP instance on a curve $E$ defined over $\mathbb{F}_p$ for prime $p$, to a discrete-log instance in $\mathbb{F}_{p^k}$ for some $k$. It is referred to as the embedding degree, and is the smallest integer $k$ such that the order of the curve divides $p^k-1$.
(One way to do this is ... |
Good afternoon . Please tell me how to change the md5 hash of one wav file to the md5 hash of another wav file. I want to bypass the anti-cheat check on md5. Maybe there are online paid services? I know English badly. I know that there have already been similar topics, but I could not do anything. Thanks!
|
I am trying to show that by breaking the Computational Diffie-Hellmann (CDH) assumption one also breaks the Diffie-Hellmann inverse assumption. Unfortunately, I am a bit stuck and do not know where to go. I suspect that bilinearity property from the pairing group given by $PGGen$ is at fault, but I do not know quite su... |
I want to sign all of the HTML and JavaScript from my site with the site's TLS private key.
(The hex signature will be preceded with a <!-- comment which is valid for both HTML and JavaScript, and attached to the end of the text files.)
This is so that end users can prove that malicious JavaScript came from us, and so ... |
There is a statement in the paper "Asymptotically Efficient Lattice-Based Digital
Signatures" by Lyubashevsky and Micciancio that says that "it is important that the ring of integers of $\mathbb{Q}(ζ)$, is efficiently samplable in practice - which is not known to be the case for particularly compact choices." Note tha... |
In BLS multi-signature aggregation scheme we can combine different signatures of different peers into one single signature, and then we can verify whether the aggregated signature is truly signed by the claimed peers.
My questions is, having an aggregated signature, is it possible to separate the signatures and achieve... |
Linear feedback shift registers (LFSR's) work by taking a fixed-length bit-string $b\in\{0,1\}^n$, as well as fixed "taps" (bit positions) and applying XOR to the taps, giving one output bit, which is appended at the $b$ after shifting it.
Now XOR is a linear function. A natural non-linear function that can be used on ... |
I'm junior software developer and I need to implement a very simple authentication system based on Chaum-Pedersen ZKP Protocol.
I know nothing about cryptography and I ask you to help me understand one thing in algorithm. An algorithm looks as follows:
I just can't get what $q$ is. I've read about protocol in Cryptogr... |
Consider the group $$ℤ^*_{55}$$
Is exponentiating to the 3rd power a permutation of: $$ℤ^*_{55}$$ And exponentiation to the 5th power?
I'm trying to solve this problem related to groups, but I don't know how to do it. Is there a mechanical way to find it? Something like a formula?
|
I've been working on the RSA method for several weeks and I don't understand what this residual class ring is all about.
I understand that if
$
x^e \bmod n$ there must be $x<n$ because of the clarity of the results
However, I don't understand what other advantages it brings.
When I look for manipulation attempts... |
About collision-resistant hash functions, in Katz's Introduction to Modern Cryptography,
6.1 Definitions
Hash functions are simply functions that take inputs of some length and
compress them into short, fixed-length outputs. The classic use of (non-
cryptographic) hash functions is in data structures, where they can b... |
Let's suppose I want to convert a Substitution-permutation network block cipher like Kuznyechik to a version with a larger block size.
Should its S-boxes be enlarged too in order to achieve similar security?
|
I just learnt the definition of hardcore bit, and I have no intuition about this. I want to know what are the possible approaches to this problem.
|
In a searchable encryption scheme based on the certificateless cryptosystem, the trapdoor generation algorithm only has a hash function that outputs an integer value. Does the scheme satisfy trapdoor indistinguishability? If so, how can we prove it?
|
Am following the instructions on https://datatracker.ietf.org/doc/html/rfc5649#section-3 ("AES Key Wrap with Padding Algorithm") and I have gotten to a point where I need to generate the LSB(32,A) for the Alternative Initial Value (AIV). Am using NodeJS with buffers to implement the algorithm. My understanding is 32-bi... |
I am evaluating ways to reduce the overhead of (H)MACs on small messages. I was primarily wondering if there is a difference between halving the MAC length or keeping the same MAC length but using it to authenticate a message of twice the size.
My initial thought was that the message/MAC ration would be the same though... |
Black box generic models prohibit calculation of discrete logarithm in groups of order $q=2p+1$ where $p,q$ are random primes to $\Omega(\sqrt{p})$ steps (refer Discrete Logarithm in the generic group model is hard - Theorem by Shoup).
Do the black box generic models also prohibit MSB of discrete logarithm to $\Omega(\... |
I am trying to understand the AES-256 encryption algorithm as it would be implemented on a gated quantum computer (actually, a simulator), and I am having some trouble understanding the theory behind it. The papers I read start with the ring of polynomials given by $F_2[x]/(1 + x + x^3 + x^6 + x^8)$. What is the signif... |
i just a bit confused that is it reasonable to assume that the probability of sending message $m \in M$ is uniformly distributed over the message space $M$? How is this different from assuming that the key $k$ is uniformly selected from the key space $K$?
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For some encryption scheme $(\mathcal{E}, \mathcal{D})$:
In the definition of IND-CCA, the adversary $\mathcal{A}$ can access the decryption oracle $\mathcal{D}$. The deep reason of this setting is to make sure that our scheme is able to "protect the ciphertexts" (e.g. the integrity and authenticity).
So "protecting t... |
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