instruction stringlengths 32 27.2k |
|---|
I am really new to cryptography and I have asked a similar question which is about Decisional Diffie-Hellman assumption (What's the meaning of asterisk and PPT in this paper?) and it is already kind of difficult to me.
But this paper Practical Secure Aggregation for Privacy-Preserving Machine Learning (https://eprint.i... |
Basic question: ENT seems to trip up generators that pass NIST 800-22 and maybe even dieharder. How do the latter two test suites miss such an obvious failure?
There are two things I want to mention about the well-known randomness test suite ENT, which is, as far as I understand, considered to be far less rigorous than... |
Consider the DSA digital signature scheme.
Does the intercepted message m||s||r contain all information about the signer’s private key? Please justify your answer carefully.
Please note that the equation $a = αx \mod p$ does give all the information about $x$ in the range $0 ≤ x ≤ p − 2$ when $a$, $p$, and the primitiv... |
Given an one-key cipher such that:
$E[k_1,E(k_2,m)]=E[k_2, E(k_1, m)]$
Is there any key distribution protocol that involves only two parties (Alice and Bob) without the key distribution center?
The protocol should allow Alice to send a session key to Bob with confidentiality using the one-key cipher.
|
I understand that there are symmetric and asymmetric (public-key) cyphers. The first have the same key used for encryption and decryption, while the second use a public key for encryption and a private key for decryption.
I understand that there are block and stream cyphers. The first work on rounds through the various... |
In the knowledge soundness definition page 8 of Groth16, it says: The extractor gets full access to the adversary’s state, including any random coins. My question is why full access? Why we just don't say oracle access to the adversary?
Then in the definition of witness-extended emulation (WEE) in Bulletproof (page 10)... |
Let's suppose I want to do One-Time-Pad but I only have a biased true random number generator (TRNG).
I XOR to the ciphertext block with another with random data got from the TRNG, e repeat the process two or more times with different random blocks.
Will this scheme make the One-Time-Pad more secure? Will this provide ... |
Reference paper: "A CERTIFIED DIGITAL SIGNATURE"
With reference to the image above which is from Page 20 of the attached paper. What is this new protocol that the paper speaks of here? What does "transmitting Yi to B just before signing a message" mean? How does it differ from the default case? How could anyone claim... |
I have a bunch of signatures (1000) signed with ECDSA secp256k1 curve. I can verify all of them with the same public key.
I have studied attacks are performed against ECDSA signatures using known MSB or LSB of the nonce.
Is private key recovery possible if nonce $k$ value is of unknown length? None of the signatures ha... |
I'm currently working on replacing the chacha20 encryption in my app with chacha20poly1305, but I'm running into a few questions that I can't seem to find clear answers to, mainly stemming from the Rust chacha20poly1305 crate:
Why does the chacha20poly1305 crate require a nonce for every message, but chacha20 only req... |
I am looking at wrapping AES keys with RSA. In NIST SP 800-57 Part 1 Recommendation for Key Management, pg 55 it is estimated that the RSA security-strength equivalent of symmetric AES-256 key would be a RSA key with 15360 bits modulus. This RSA key size looks impractical, and mostly not even available due to technical... |
I want to implement a client that generates random 48-bit values and send them as broadcast messages. We assume also there is a legitimate receiver getting those values (so, there is some sort of pre-authentication that has already happened but it is not of importance here. We can also assume the client/receiver share ... |
As far as I understand, a property is computational if it holds in a computationally-bounded context, so for ANY computationally-bounded involved entity (even if an unbounded one could discover the property is actually missing): e.g. any computationally-bounded distinguisher evaluating two transcripts to check CZK, or ... |
I want to use the asymmetric encription offered by a tool to encrypt my files and I would like to know if the following encryption process works, regardless of perhaps not optimal use.
Generate a 32-bytes-random-key inside the browser with window.crypto.getRandomValues
use sjcl crypto library for:
choosing AES algor... |
Various proposals are being explored for X509 V3 certificates in a Post Quantum Cryptography (PQC) world.
Currently, these include just having a certificate for classical and PQ, having a hybrid certificate for classical and PQ using X509 extensions or composite certificates that concatenate as many signatures into one... |
Given the coin flipping protocol:
A chooses $a \in_R \{0,1\}$ and computes $commit(a,r)$. She sends $commit(a,r)$ to B.
B chooses $b \in_R \{0,1\}$ and sends $b$ to A.
A sends $open(a,r)$ and B checks if the opening is valid.
Both output $coin = a \oplus b$
where $commit$ is the commitment scheme used by Alice.
I am ... |
I've know that a PRF Xored with its key is not a secure PRF. Then I wonder that what if the Xored (or multiplied) item is another random number. The formal expression is as belows:
Let $F_k(x):\{0,1\}^n \times \{0,1\}^n \rightarrow \{0,1\}^n$ be a PRF.
"$<<$" operation indicates left rotation, "$\cdot$" operation indic... |
Summary. Given some dimension $n$ (say $n=50$), is it possible to describe explicitly a lattice $L$ and a basis $B$ of $L$ such that
$$ \frac{ \| LLL(B)_1 \| }{ \lambda_1(L) } > 1.02^n $$
where $LLL(B)_1$ is the first vector of the LLL-reduced basis of $B$ (for $\delta=1$ say)? The constant 1.02 is the one given in "LL... |
Alice has an ElGamal public key $y=g^x$. Bob encrypts a value $g^b$ based on Alice's Elgamal public key and he ends up with a ciphertext $(g^by^r, g^r)$. Can Bob prove that the value $b$ is in some range without revealing it or do you need to be the "owner" of the ElGamal secret key $x$ to create such proofs?
If $g^b$... |
I'm trying to understand the GF theory, but every time I come across information about AES it all makes no sense.
In my opinion $GF(2^8)$ defines any polynomial of the form:
$a_{7} x^7 + a_{6} x^6 + a_{5} x^5 + a_{4} x^4 + a_{3} x^3 + a_{2} x^2 + a_{1} x^1 + a_{0}$
Where $a_{i}$ can be 0 or 1. And everywhere I come acr... |
skinny cipher has been lately considered as ISO/IEC standard while is still competing as building block of Romulus AEAD in NIST LWC finalists.
what is the difference between the two ISO and NIST processes? which is higher hand in the industry adoption ?
|
I implemented carry-less multiplciation using the CLMUL instruction set. This is similarly fast to simple modulo multiplication. But computating the result mod some polynomial is still very slow. I do it this way:
for (unsigned int i = 32; i-- > 0; )
{
if (c & (1L << (i + 32)))
{
c ^= 1L << (i + 32);
... |
I am wondering if there is any available threshold crypto library that is well-audited and ready to be used in production.
Any pointer is appreciated.
|
Leaving memory-hardness assumptions aside, some slow hash functions are iterated salted hash-chain versions of regular cryptographic hashes. This is usually defined by a round parameter i.e., in PBKDF2. Is there any cryptography paper that addresses security-bits definition based on the factor of rounds of linear succe... |
Certificates are used very often in crypto. From the search, I am a bit confused what exactly is the "public key" inside a certificate essentially? Is it always a signature verification key, or could it also be the encryption key?
In my understanding, for root and intermediate CA certificates, the public key is always ... |
Assume two end-points $A, B$. $A$ sends to $B$ a $Hash(pv||key)$, where $pv$ is a public value that can be intercepted by attackers. The $key$ is a common secure shared key in both end-points, and $||$ denotes concatenation. Obviously, end-point $B$ has all the info required to check the received hash. I was wondering ... |
Let's consider for simplicity Middle-Square Weyl Sequence RNG:
https://arxiv.org/pdf/1704.00358.pdf
We can choose there parameter for independent stream generation, we can call it key. Let's consider we would use it as a stream cipher, so stream is xored with plaintext.
But what it mean to broke such a cipher? Even if ... |
So I was casually practicing RSA on paper for an exam, I did the whole process I wrote bellow, and when I tried the encryption and decryption I got distracted and instead of doing $m^e \mod n$
I did $m^e \mod {\phi(n)}$ and both the decryption and encryption worked.
Is this normal?
Here are the numbers:
$$
p = 11\\
q =... |
I read here:
https://www.researchgate.net/publication/220335697_GCM_GHASH_and_Weak_Keys
how GHASH works. So we have $m$ 128-bit blocks $X_{i}$ and we compute in $GF(2^{128})$:
$Y_{m} = \sum_{i=1}^{m} X_{i} \times H^{m-i+1}$
$H$ is a key. Am I see right there that $H$ is raised to the power? Is there method to do it fas... |
I'm a bit confused on how to validate the authentication tag between two different AES GCM implementations.
One implementation (on my part) is in Java. The other, I don't know.
In my implementation, the plaintext is encrypted with the doFinal function. I prepend the initialization vector to the result.
I understand tha... |
I'm trying to understand that scheme:
https://xilinx.github.io/Vitis_Libraries/security/2019.2/guide_L1/internals/gcm.html
Here on page 11 it looks like GHASH gives only one value "Return $Y_m$":
https://web.cs.ucdavis.edu/~rogaway/ocb/gcm.pdf
After hashing several subsequent blocks. It make no sense to me. If I under... |
According to wikipedia:
https://en.wikipedia.org/wiki/Rijndael_S-box
AES is doing interesting thing (where $<<<$ is circular shift):
$s = b \oplus (b \lll 1) \oplus (b \lll 2) \oplus (b \lll 3) \oplus (b \lll 4)$
and this is equal to ($\times$ is multiplication in $GF(2^8)$):
$s = b \times 31 \mod 257$
This provides a ... |
The goal is for Alice to send an encrypted message to Bob. Neither Bob nor anyone else should be able to decode the message. Alice should be be able to decode it, when all data is shown to her. However, Alice cannot store anything related to the message.
Private keys:
X1 - random bits
X2 - random bits
M - large pri... |
Given that CBC mode encryption is vulnerable to padding oracle attacks, what is the next best alternative ?
a) Include a hash check in the API scheme, validate the hash and then proceed with CBC. If hash check fails then return error indicating same. Eg: Include HMACSHA256(AES256(plaintext)) checksum that is required t... |
Looking at https://crypto.stackexchange.com/a/30616/16548 and all the ways I generate RSA keys (code, SSL) the MSB is always 1 and so when DER encoded has 0x00 prefix.
I think it is always so when the RSA key length is a power of two (e.g. 2048 or 4096).
But the question I'm wondering now before going to bed: is it so?... |
Consider a scenario：data owners $C$ sends a $l$ bits value $x$ to parties $P_0$ and $P_1$ via additively secret sharing scheme, for example, $C$ randomly selects $r \in_R \{0, 1\}^l$, and sends $r$ to $P_0$ and $x-r$ to $P_1$. In insecure channel, adversary $\mathcal{A}$ could obtain $r$ and $x-r$ to construct secret $... |
I know AES-GCM and AES-CCM but what is the difference between AES-CCM8 mode and AES-CCM mode ? Is it the length of the cipher?
|
I am trying to find a reduction for the following DLOG problem in generic groups. It is a simple generalization but I'm not finding any reference (the closest being the Chaum-Pedersen signature scheme sec 3.2, and BLS signatures without the hashing).
Let $G$ be a cyclic group, and $g, h$ generators. The problem is to f... |
Any body can explain, what are the key differences between Shannon entropy and Guessing Entropy? In some research I got entropy uses binary search or balanced Huffman tree. Guesswork uses linear and unbalances Huffman tree?
Also guesswork can calculate unlimited guessing?
|
I'm reading Understanding Cryptography by Christof Paar and Jan Pelzl. In chapter 2 (Stream Ciphers) there's a question that goes like this:
Assume we have a stream cipher whose period is quite short. We happen to
know that the period is 150–200 bit in length. We assume that we do not know
anything else about the inte... |
Let's consider this definition of computational indistinguishability.
Computational indistinguishability. A probability ensemble $X=\{X(a, n)\}_{a \in\{0,1\}^{*} ; n \in \mathbb{N}}$ is an infinite sequence of random variables indexed by $a \in\{0,1\}^{*}$ and $n \in \mathbb{N}$. In the context of secure computation, t... |
In Hebrew language there is the term tzophen (צופן) which means cipher.
There is also a term "maphtech hatzpana" (מפתח הצפנה) which means "ciphering key".
What is a ciphering key?
Cipher, as far as I know, is a matter of resorting characters to get a meaningful message, so what "key" is needed to do so?
It might be th... |
I need to design a Σ-protocol ZKP using Pedersen commitment scheme that proves knowledge of a, y such that statement A = h^y * g^a only holds for even y (y=2x).
Of course, the protocol needs to be sound, special-sound, and honest-verifier zero-knowledge.
Any suggestions?
|
Is it possible for an attacker on a Diffie-Hellman key exchange to manipulate both sides in a way so that the secret generated on each side is identical?
Or put differently, would it be possible to detect an attack via MITM if we can detect via a different channel that the secrets of both parties do not match?
|
Why I care: I want to implement some secure sessions for communicating over internet and since I am a complete amateur in this and don't want to spend a lot of time learning about cryptography or about specific libraries (as I am doing this only for fun), I want to have minimal preparation from programming side. From m... |
Let $E$ be a known, "secure" curve, defined over a field $\mathbb{F}_q$ where $q$ is either a prime $\geq 5$ or a power of $2$. Denote by $n$ the amount of rational points of $E$.
Consider $E/\mathbb{F}_{q^2}$, the same curve but defined over the 2-degree extension field. It is clear that any $E(\mathbb{F}_q)$ is a sub... |
I had a brief look at "On Defining Proofs of Knowledge" by Bellare and Goldreich and I am a little confused by their definitions.
I was under the impression a negligible function $f$ was defined as something like
$$\forall\ polynomials\ p\ \exists k\ s.t.\ \forall x > k: f(x) < \frac{1}{p(x)}$$
And that non-negligible ... |
I am trying to figure out when to use a new IV for an AES-CBC communication and whether my approach is safe.
Here is a quote from Thomas Pornin from a similar question:
So, to sum up: you must choose a new, random IV (with a
cryptographically strong generator) whenever you are about to encrypt
plaintext data which was... |
I am currently reading about Trapdoor Permutations (TDP). While I can totally understand and think of examples of TDP. I cannot think of any examples of Enhanced TDP. The definition of both TDP and Enhanced TDP is given below :
Standard Trapdoor Permutations Collection : It is a collection of finite permutations, denot... |
A collection of hash functions $H=\{h:\{0,1\}^n \to \{0,1\}^m\}$ is pairwise independent if for every $x_1 \neq x_2 \in \{0,1\}^n$ and $y_1, y_2 \in \{0,1\}^m$:
$$ \Pr_{h \leftarrow H}[h(x_1)=y_1 \wedge h(x_2)=y_2]=\frac{1}{2^{2m}} $$
Given a finite field $\mathbb{F}$ of size $2^n$ I've been able to prove for the set o... |
I'm trying to implement the RSA algorithm with some random (valid as far as I know) generated values but for this combination, encryption/decryption doesn't work.
message = 324
p = 3
q = 29
n = 87
e = 15
d = 15
Which give both and encrypted and decrypted answer of 63
I'm guessing I made and error while generating the ... |
Suppose that we have a block cipher such that the last round of the cipher depends on half of the key and the penultimate round uses the other half.
Suppose also that I attacked the last round using differential cryptanalysis and reduced my search space from 2^8 to 2 choices for each byte of that half of the key.
One w... |
RFC 4880 section 5.2.3.16, "Notation Data," describes how arbitrary additional notations in the form of name-value pairs can be included in an OpenPGP signature packet. Regarding names, it says the following:
Notation names are arbitrary strings encoded in UTF-8. They reside in two namespaces: The IETF namespace and ... |
Let's say that I have a password. And it's secure. But it's a 10-character string.
So If I wanted to create an AES key for the 128-bit version of the algorithm I would just hash it using MD5. Or If I wanted the 256 version of the algorithm I would hash it with any of the 256 length hash functions such as Sha_256. But I... |
Using SHA-256 as a stream cipher appears to bear cryptographic weaknesses, however, I am not quite sure how to implement them in decryption.
Assume that I have an encryption function using 64-byte blocks.
I encrypt each of the blocks with the hash of the previous to produce my ciphertext.
The weak link here is, that I ... |
assume Bob and Alice use Elgamal encryption scheme. Alice wants to send Bob a message, but does not know Bobs public key. Is there a way for Alice to find out Bobs public key by receiving multiple message pairs C1 (ephemeral key) and C2 (message) from Bob? Alice can easily decrypt Bobs messages, as from Bob to Alice th... |
While implementing a protocol in Scyther, I need help with the following questions -
How do we split a particular message/variable into two parts in Scyther?
(For eg. if I have value R in my protocol that I need to divide into two parts say K1 and K2, how do I go about doing it in Scyther. I tried R=CONCAT(K1, K2) whe... |
In RLWE,
we often choose the following polynomial ring,
where q is a prime,
and n is a power of 2, e.g. $2^k$
$$\mathbb Z_q[X]/(X^n + 1)$$
We know that ${X^{2^k}} + 1$ is an irreducible polynomial under $Z$,
because of Cyclotomic Polynomial,
but in this question,
Considering $$\mathbb Z_{17}[X]/(X^4 + 1)$$
$(X^4 + 1)$ ... |
I've been trying to make an algorithm work like the real Enigma machine, fully customizable. I use two online emulators to check that my encoded message is correct :
https://cryptii.com/pipes/enigma-machine
https://www.101computing.net/enigma-machine-emulator/
Currently, without the plugboard, it seems that it works ... |
The purpose of a block cipher is to act like a random permutation, and indeed a common security definition is one in which the block cipher is taken to be indistinguishable from a random permutation (see Wikipedia). So then why not use a random permutation as a block cipher? That is, the secret key could just be a li... |
I'm writing my term paper on bandwidth restrictions between varying generations of PCI-E lanes using the 1x interface of the lane and exploring modern bandwidth restrictions when mining using the latest GPUs.
GPU risers themselves use the 1x lane and I've been looking at the PCI-E wiki to analyze these restrictions:
ht... |
Suppose that we have a symmetric 256-bit master key, and we want to encrypt using AES-GCM with random IVs. I understand that with random IVs, the lifetime of the master key is 2^32 in order to conform to NIST requirements.
Let's assume that we want to increase the lifetime of the master key. Can we do this by adding a ... |
The documentation for Ed25519-dalek states the following for Secretkey:
The caller is responsible for ensuring that the bytes represent a masked secret key.
https://docs.rs/ed25519-dalek/0.3.2/ed25519_dalek/struct.SecretKey.html
What does a masked secret key mean in this context?
|
In this question one way is shown how to prove the possession of a private x25519 key.
Would the following protocol also be suitable to prevent someone from using the client as a decryption Oracle?
Server generates some 'nonce' and an ephemeral x25519 key pair. The sever sends the nonce and the public x25519 key to th... |
I'm currently reading this How To Simulate It – A Tutorial on the Simulation Proof Technique.
On p. 10, there is a proof using simulation for 1/2-OT, against semi-honest adversaries. Briefly, the player $P_1$ holds the messages $b_0$, $b_1$ and the player $P_2$ hold the choice bit $σ$. Since $P_1$ has no output, it cre... |
I have a branching in c++:
if (x & 1)
{
x = function_1(x);
}
else
{
x = function_2(x);
}
If function_1 and function_2 are constant time and it takes the same time to compute them, is such branching still vulnerable for side-channel attacks? Can attacker somehow know which condition was executed?
|
The multiplicative inverse in AES s-box is transformed using the following affine transformation:
$s = b \oplus (b \lll 1) \oplus (b \lll 2) \oplus (b \lll 3) \oplus (b \lll 4) \oplus 99_{10}$
Where did the number 99 come from? For what purpose is it there?
I'm asking, because I'm trying to generalize it in $GF(2^{128}... |
I am working on implementing ECDH with some HSM. According to the theory behind ECDH, the generated shared secret is a point on the elliptic curve (x, y) which is exactly what is returned by the HSM.
But when I test with SoftHSM via PKCS#11 library, the ECDH function returns a symmetric key directly even with KDF param... |
so I wanted to ask something since I just learned about cryptography. Here where I have the task to write an essay on cryptography and the title I have to do is introduction digram analysis. However, I did not find any information about digram analysis. What I know is this digram analysis is used on stream and block ci... |
Section 3.3.5 of the paper “Schwaemm and Esch: Lightweight Authenticated Encryption and
Hashing using the Sparkle Permutation Family” (the link to PDF can be found in this page) contains the following text:
Alzette provides very fast diffusion. In particular, all outputs bits depend on all the input bits
after 4 round... |
If you look at the AES Linear Approximation Table (computed for example with Sage) you will see there are many entries with what looks like a high bias of -16 ("absolute bias" scale).
I know AES is designed to be resistant to Linear cryptanalysis.
If you agree that -16 is a high bias, then there are 2 (3) options:
ei... |
I came across a comment about AES 128 without ShiftRow. I want to use this weakness to perform an attack. So far, I get that It possible to divide in 4 independent blocks of 32 bits. So we can launch a attack independently for each block. However, as the key scheduling use all the master key, I don't know if it is poss... |
I need test vectors for E382 and E521 edward curves in order to test signature and verification process of a software.
|
We know that in RSA algorithm Sender A can send an encrypted message to receiver B without any prior exchange of secret keys. A just uses B's public key to encrypt the message and B decrypts it using the private key, which only he knows.
In digital signature reverse RSA algorithm can also be used to sign a message, so ... |
What is an advantage of the Charles--Lauter--Goren hash function (based on isogenies of elliptic curves) among other provably secure collision-resistance hash functions ? I heard that it is slower.
|
TL;DR: This ABSOLUTELY does not work and presents a huge security risk. Posting it anyways in case there are other threats I missed or to dissuade any other person who comes up with this idea.
Hi! I’m sort of new to cryptography. I’m starting to venture into ZK schemes. For a small project of mine with which I intend t... |
Are there any functions f, g and h, such that:
f is one-way and is used to generate an encrypted message c when applied to message m with a public key (c = f(m, N))
Original message m can only be obtained from c in polynomial time (decrypted) if a private key (k) is known
A new encrypted message (c') for a desired rec... |
When multiplying polynomials from $\mathbb{Z}_q[X] / (X^n-1) $, the discrete NTT is used because: $$ f \cdot g = \mathsf{NTT}_n^{-1}\left( \mathsf{NTT}_n\left(f\right) * \mathsf{NTT}_n\left(g\right) \right) $$
However, in virtually all schemes I've seen the negacyclic convolution is used - the ring is $\mathbb{Z}_q[X] ... |
Definition of XOR-Universal hash functions by Abidin[1]:
A class $H$ of hash functions from $M$ to $T$ is XOR-Universal$_2$ ($XU_2$) if there exist at most $|H|/|T|$ hash functions $h$ $\in$ $H$ such that $(h(m_1) = h(m_2$) $\oplus t)$ for any two distinct $m_1$, $m_2$ $\in$ $M$ and any $t \in T$.
If there are at most... |
I have to write an essay on the paper ad hoc multi-input functional encryption, and can't understand the security definition. In a nutshell it is a primitive that allow sources to supply encrypted data, such that at any point a dynamically-chosen subset of
sources can allow an agreed-upon joint function of their data ... |
I'm looking for a non-invertible bijective function mapping a 64bit value into another 64bit value.
I can't use a hash because it isn't bijective.
Could this be done with public key cryptography ? The key and function may be big. It's just the data that would be small. I would destroy the private key as I never need to... |
If $P$ and $Q$ are two points on an elliptic curve of large prime order, given $P, Q$, and a point $R$ which is either (a) $nP$ or (b) $nQ$, is it possible to determine if $R$ is of form (a) or form (b)? Here $n$ is a secret.
|
I remember reading somewhere that sometimes in some stream ciphers it is necessary to skip the first values they produce. I can't find any information on this right now.
But it seems to make sense. Just as a hash function needs to do many rounds before it returns a random result, the CSPRNG needs some number of iterati... |
RSA challenge is well-known and it has a wiki page.
Is there a discrete log for $\mathbb F_p$ where $p$ is Sophie-Germain prime?
|
The S-box is defined as the generalised inverse function $S:\mathbb{F}_{2^n}\rightarrow \mathbb{F}_{2^n}$,in quotient ring $\mathcal{R}:=\mathbb{F}_{2^n}[X]/(X^{2^n}-X)$
with $S(x)=x^{-1}$, is correct $S(X):=X^{2^n-2}$.
But the Euler's theorem says $x^{\varphi(n)}\equiv1\pmod{n}$,so the answer is $x^{\varphi(n)-1}=x^{... |
I am reading the 800-90B document.
In particular, I'm looking at Chapter 5, the chapter on checking that samples conform to IID.
There are 11 tests such as Excursion Test Statistic and Number of Directional Runs. All these tests can be performed on binary data as well as non-binary data.
In the case of some tests, in t... |
How to caculate the inverse of function $x^3$ in $\mathbb{F}_{2^n}$?,
Any monomial $x^d$ is a permutation in the field $\mathbb{F}_{2^n}$ iff $gdc(d,2^{n}-1)=1$,why?
|
This paper On Ideal Lattices and Learning with Errors Over Rings proposed RLWE which is Ring and hence efficient version of LWE problem. My question is that they considered cyclotomic polynomials for modulus. I am not sure why cyclotomic polynomials are used and what extra advantage we get by using them?
|
In the traditional 1-out-of-n OT, we suppose Alice has an array $A=\{x_1,{\cdots},x_n\}$ and Bob has $idx=i\in\{1,{\cdots},n\}$. After running the OT, Bob leans $x_i$ and nothing else, Alice learns nothing about $i$.
So, my question: is there a "shared" variant of 1-out-of-N oblivious transfer?
We consider the array an... |
I'm told that TLS 1.3 supports only non-committing authenticated encryption schemes. What is a non-committing authenticated encryption scheme? What is the difference between committing and non-committing authenticated encryption schemes? What are the pros and cons?
|
I have been through several sources and papers, but I can't seem to find how these rotation constants were created. Are these constants arbitrary, or were there chosen by some kind of permutation? I can't really find any source.
The order of the left rotates on the left hand side are:
{{11, 14, 15, 12, 5, 8, 7, 9, 11, ... |
I am building my own MQTT based network for which I would generate my own ca/server/client certificates for authentication.
The goal here is to keep the message sizes as small as possible so as to reduce the bandwidth traffic, but I already know that the TLS layer adds quite an overhead to the traffic it sends. Namely,... |
I am curious why equations for signing/validating with ECDSA have forms they have. Is it possible to use simpler equation that have same properties.
For example, this is an equation I found in the book on Bitcoin:
$$
s = (z + re)/k
$$
where,
$r = x\_coordinate\_of(k \cdot G)$,
$e$ - private key,
$z$ - message hash,
$k$... |
An elliptic curve defined over a finite field is either cyclic, or a direct sum of two cyclic groups. In cryptography, we use exclusively the former. I was wondering if there is any result on how common (or rare) are rank-2 elliptic curves defined over $\mathbb{F}_{q}$ for a prime power $q$.
(They don't seem rare. For ... |
In the case of sponge construction, it is shown to be differentiable from a RO. In the paper by Bertoni et al., what is meant by the node being saturated. How does it become saturated and the condition which leads to error in the simulator was not clear.
Paper link: http://citeseerx.ist.psu.edu/viewdoc/download;jsessio... |
Is the random picking of big n-bits random numbers for primality test a time sensitive operation?
If so, would an heuristic for limiting the search space (about 5-10x) without missing out on any prime be an interesting addition?
|
Is it possible to take some value text like “Hello World!” And encrypt it with a random key. Then take the encrypted message and encrypt it again with another random key. And so on…
Then can you write a function that takes in the final encrypted message plus any one of the keys from before and return True or False. Wit... |
Currently I am working on a public api that uses token authentication. The token is a 32 bit random hex that is shared with the user and then stored in our database as an HMAC digest using a secret key. The token is not stored except for the first 4 characters.
My question is, is it safe to store the prefix like this?
... |
I am new to cryptography and I cant get my head around this issue:
If symmetric cryptography is faster then asymmetric and given that Diffie-Hellman key exchange algorithm allows you to exchange keys safely why bother using Asymmetric cryptography if I can exchange symmetric keys safely ?
|
I am reading Introduction to Modern Cryptography 3rd Edition (Google Books Preview of Relevant section, pages 10-11) and am struggling to understand the description of an attack method on a monoalphabetic substitution cipher.
It seems to be an improved version of a letter-frequency analysis approach, eliminating the ne... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.