instruction stringlengths 32 27.2k |
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A HRNG that is NIST 800-90 compliant must use a DRBG in some way regardless of whether it adheres to a RBG1, RBG2 RBG3(XOR), or RBG3(RS) construction. This violates the requirement that the OTP is truly random (since there is a DRBG involved). Therefore, it is true that a NIST 800-90 compliant device cannot be used to ... |
If we know the RSA encryption of messages m, m+1, m+2 when c=3, how can we compute m in polynomial time?
|
I wanna generate a list of numbers based on a unique string. They shouldn't be predicatble and every time to generate they are the same.
Could someone help me pleeease :)?
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I am testing my TLS 1.3 server (it does not use openssl library) using openssl s_client utility. I have found out that s_client can not decrypt encrypted extensions of the server. So I need to know parameters of decryption used by s_client.
Could you tell me:
How can I force s_client to output (if it is possible) keyi... |
Diffie-Hellman key exchange is sometimes informally said to be hard under the discrete logarithm assumption in the chosen group. But if I am reading literature correctly, it actually uses a stronger assumption on the group and that's the assumption of Decisional Diffie-Hellman.
Is there a key exchange whose SK-security... |
I want to perform a modular reduction using Solinas prime value as q = 2^383-2^33+1. How can I efficiently compute it taking advantage of q being Solinas prime?
|
From the PLONK paper.
Page 29, Round 3
Why multiply z(x) and z(Xw) in the quotient polynomial? (why does internal wiring have to multiply input permutation)
Why the second term have to "shift by w"?
My observation is:
These 2 lines seem they have to cancel each other out.
z(x) is permutation polynomial and only about... |
My lecture notes state that of the AES operating modes ECB, CBC, CTR, CCM (CTR+CBC MAC) and GCM, only CCM and GCM provide authenticity.
In CCM, as I understand it, the authenticity lies in the MAC, i.e. the symmetric key.
AES-GCM calculates the authentication tag (AT) using, among other things, the additional authentic... |
A $m$-dimentional full-rank integer lattice $\Lambda\in\mathbb{Z}^{m}$ can be defined as the set of all integer linear combinations of $m$ linearly independent over $\mathbb{R}$ basis vectors $\textbf{B}=\{\vec{b}_{1},\ldots,\vec{b}_{m}\}\subset\mathbb{Z}^{m}$:
$$\lambda=\mathcal{L}(\textbf{B})=\left\{\textbf{B}\vec{c}... |
I am considering using a hybrid approach by combining ECIES (Elliptic Curve Integrated Encryption Scheme) with Kyber KEX (Kyber Key Exchange) for secure communication. Instead of using the traditional Curve25519 key exchange in ECIES, I want to replace it with Kyber KEX, which is post-quantum secure. This way, I would ... |
I am working on a proof for a secure aggregation protocol in which the server aggregates values from several clients. A challenge in the proof is that the server may lie about which clients have dropped out, requiring the simulator to equivocate the encrypted values it has sent to end up with the correct output on the ... |
In go/src/crypto/internal/nistec/p256_asm_arm64.s Line 448 / 473 / 498 / 524, We can see the code mul Ord with hlp1 but NOT hlp0. According Montgomery Multiplication, shouldn't we mul Ord with hlp0?
// First reduction step
MUL acc0, hlp1, hlp0
MUL const0, hlp1, t0
ADDS t0, acc0, acc0
UMULH con... |
This is from this video - https://www.youtube.com/watch?v=9VuZvdxFZQo
Bob has a list of length $10^6$. Bob wants to convince Alice that every number in the list is between 1 & 10. Alice needs to verify it with just 2 queries & 99% certainty.
This is the protocol given by Ben
$f$ is polynomial created by interpolating ... |
In the document Trapdoors for Lattices, section 5.4 Gaussian Sampling, they introduce the parameter $\sqrt{\Sigma_{\bf G}}$, which is related to the lattice $\Lambda^\perp(\bf G)$. They use it as a bound for the smoothing parameter of this lattice, therefore $\sqrt{\Sigma_{\bf G}}\in\mathbb{R}$. But later on, they do s... |
I am trying to do some calculations with the Paillier Homomorphic encryption scheme. Specifically, given three plain text integers, x1, x2,and x3. I want to first encrypt them, getting their corresponding ciphertexts, say c1, c2 and c3. I want to find the results of (x1+x2+x3)/3 by utilizing c1, c2, c3 and the homomorp... |
I would like to encrypt big files using an authenticated cipher. I am convinced to use approach where file is divided into smaller manageable chunks that fit easily in memory (e.g. 1-10MB size) which are encrypted, authenticated separately.
Unfortunately such approach is prone to "reordering" attack at least.
I am look... |
If Bob takes a plaintext and encrypts it with their own public key and hands it to Eve who in turn encrypts it with her public key, we now have a cipher text that requires both Bob and Eve to decrypt it, to get the original plaintext.
However once Eve has encrypted it, is there anything Bob can do to confirm that the c... |
I am trying to prove to myself that an identification scheme derived from a digital signature in a challenge/response manner is secure, based on the security of the digital signature scheme. I've found an informal proof in these lecture notes, but I'm struggling to formalize it with a reduction.
Let $\Sigma = (GEN, SI... |
I am using ECDSA P-384 for signing and verifying messages. The messages are basically stringified JSON. After receiving, the recipient verifies the signature using the public key.
Should the public key be included inside the message (aka the JSON which gets stringified)? Or should I send the public key separately along... |
Consider the following definition. Let $p(n) > n$ be a polynomial, and $G_n: \{0, 1\}^n \rightarrow \{0, 1\}^{p(n)}$ a PRG. Moreover, given $x \leftarrow \{0, 1\}^n$, we say $S$ is a length $n-1$ contiguous substring of $G(x)$ if $S = s_0\cdots s_{n-2}$ with $s_i \in \{0, 1\}$ is a contiguous substring of $G(x)$.
Then... |
I have a decentralized coin system that I am trying to develop.
Each coin can be split up into 1,000,000 units.
I've been looking for a quantum-safe and practical (efficient) algorithm to send fractions of a coin between peers, so that other than the two peers that participate in the transaction, nobody could tell the ... |
I'm researching to see if there is an algorithm that encrypts different inputs with different keys to produce the same output.
So let's say I have 2 messages.
var message1 = "My password is: Doggies!1"
var message2 = "My password is shdhe93-4"
And two keys.
var key1 = "DummyKey"
var key2 = "RealKey"
I would like to... |
Suppose my server receives a message, the public key, and the signature. The message contains a time stamp.
Is there a way to get the time stamp from the signature to match it with the message time stamp. Or some other way to ensure the message was signed at the time that it says it was signed?
I am using ECDSA P-384 b... |
Let $r(b, t)$ denote the bitstring $b$ rotated to the left by $t$ bits: for example, $r(00110101, 5) = 10100110.$
Consider the following game. Player A picks two (different) $n$-bit strings $(T_1, T_2)$ and four arbitrary numbers $(a, b, c, d)$ less than $n$. Then Player A computes $$B_1 = r(T_1, a) \oplus r(T_2, b)$$ ... |
Let $F = GF(2^n)$ and $P(x) = x^e, P : F \rightarrow F$ be a monomial of degree $e$. How to write each bit of the output of $P$ as a function of input bits? In other words, how to write it as a system of polynomials over $GF(2)$?
One way is to use computer algebra systems such as sage and work as follow:
sage: p = 2
sa... |
I'm working on a Distributed Key Generation protocol. The idea is similar to this.
TLDR: Aggregated Shamir Secret Sharing, each participant acts as a dealer & distributed the secret shares of its secret polynomial to the rest of the participants. Finally, the actual secret can be constructed by aggregating the secret s... |
Considering that quantum computers (in theory) can break\reverse some of one-way-hashes a lot faster than conventional-computers. Is it technically feasible in any theoritical (but realistic) senarion, to store data "compressed" as in the form of an one-way-hash and reverse\restore\"decompress" it with the help of a qu... |
The python code example on Wikipedia uses the 12th Mersenne Prime ($2 ^ {127} - 1$) as the modulus. I'd like to share a 32 byte secret. Is it safe to simply change the modulus to p = $2 ^ {256} + 297$?
|
TLS 1.3 specify two pre-shared key exchange modes, which are psk_ke and psk_dhe_ke. The former is a non-ephemeral key exchange where the master secret is basically derived from the pre-shared key, the client random and the server random; whereas the latter is ephemeral and derives master secret from those same data plu... |
I am trying to understand the NIST-submissions for post-quantum cryptography a bit better, and I noticed that the submissions from the CRYSTALS-family in particular is based on Module-LWE.
I understand that "normal" LWE has huge parameters, and that they went for Ring-LWE in Ideal Lattices over Rings because of the mor... |
I am trying to understand which operations are computable by an $\texttt{NC}^1$ circuit. However, I am struggling to understand whether there is such a circuit for multiplying a matrix with a vector or if the circuit will necessarily be in $\texttt{NC}^2$.
|
By full alternatives I mean things that can do everything RSA can, namely establish secure security without privately sharing information prior. Something which AES can't do.
In other words, I'm looking for quantum-resistant asymmetric encryption.
|
The Pedersen hash is a low constraints friendly hash for Zk-Snarks.
Unlike many algorithms, the Pedersen hash returns a point P = (x,y) on a curve as a hash. Depending on the selected curve, there can exist a fast deterministic way to compute a different input that yields −P=(x,−y) using the Weierstrass form.
As a resu... |
In a similar anonymous PKE based on D-H key exchange, in a many-to-one (one-to-many) case, is there any way to implement authentication without revealing the identity of the sender (receiver)? Could you recommend some papers?
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It is DTLS 1.2 version question of this question.
I know from 4.1.2.4. of RFC 5246 (DTLS 1.2) AEAD Ciphers can be used in DTLS 1.2 exactly the same with TLS 1.2.
In TLS 1.2
AAD = seq_num + TLSCompressed.type + TLSCompressed.version +
TLSCompressed.length
It makes sense since it is (implicit) sequence number + header ... |
Given a certificate .p12 I want to extract the public key, the private key and Modulus and Exponent both from the public key and from the private key.
I am using PHP and OpenSSL functions
As I understand it, the Module and Exponent of the public key must be different from the Module and Exponent of the private key.
... |
Let's say I want to perform addition on "small" numbers (if it matters, let's say integers between 1-10K) without decrypting the numbers -- i.e. I have E(A) (the encryption of A in a crypto system under a given key) and E(B) and I want to compute E(A+B) without decrypting A or B.
The state of the art would be to use a ... |
I have following simple function
uint128_t crypto_aes_prf( ECB_Mode< AES >::Encryption& e, int message)
{
// Encrypt the input using AES
unsigned char messageBytes[16]= {0};
unsigned char ciphertext[16] = {0};
std::memcpy(messageBytes, &message, sizeof(message));
e.ProcessData(ciphertext, messageB... |
I have a program implementing a function $f$, and want to find a pair of functions $e$ and $h$ such that $h \circ e = f$, but $e^{-1}$ cannot be recovered from $h$.
In other words, given some $e$-encrypted data, $h$ decrypts it and applies $f$. Knowing $h$ doesn't allow me to get back the unencrypted data, but rather o... |
I recently looked into the subject of public key cryptography (especially with X.509 certificates). I am the administrator of a web server using HTTPS which uses 2 levels of certificates (in addition to the end-user certificate for the website). Here is the schema :
The black line is intentional to keep the anonymous.... |
I have two files ctext0 and ctext1 that are byte files and they are encoded using the same one time pad, so I tried to write a pygame program to allow me to use crib-dragging to figure out some words like so:
import pygame
import sys
import os
file_size1 = os.path.getsize('ctext0')
file_size2 = os.path.getsize('ctext1... |
Rumba20 is a compression function that maps a 192-byte (1536-bit) string to a 64-byte (512-bit) string. It's designed to provide collision resistance by using Salsa20 (or ChaCha20) with the feedforward.
However, from the Rumba20 webpage:
Rumba20 is not designed to provide unpredictability, truncated collision resistan... |
Is anyone aware of the source for a technique that incorporates external wire values into Garbled Circuits? I have come across this technique, which can be found here. However, I was unable to locate the primary reference for it.
The purpose of this technique is to reduce the number of decryption operations required du... |
I'm currently confused about the distinctions between two-party computation (2-PC), secure function evaluation, and private function evaluation. Additionally, I came across the term secure circuit evaluation, which has further added to my confusion. If these concepts are essentially the same, then why are they referred... |
I am currently studying a course in cryptography, and I have this exercise about OWF.
I'm failing to prove that this is an inverter to f. Am I in the right direction at all?
Thank you!
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I have a question regarding understanding representation of length in AES-GCM while doing padding for the IV to calculate ICB/J0.
In the aes GCM test vectors testcase5 I see the IV is of length 8 bytes as follows:
IV cafebabefacedbad
But len({})||len(IV ) is mentioned as
00000000000000000000000000000040
but since t... |
Reading about index calculus for discrete logarithm, I noticed that it works for $(\mathbb Z / p \mathbb Z)^*$. Is this the only situation in which it works? If not, please give examples of other situations in which index calculus works to solve discrete log.
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I am new in the field of cryptanalysis and wonder how the differential cryptanalysis work
|
I am trying to implement a stream cipher that uses an LFSR PRNG. I have found resources online that give good primitive polynomials, but I am struggling to find resources with the initial states as well.
I really need to be able to have something to test against so I know my code is working as intended. I would really ... |
This question may be of no practical interest. But as a meaningful or meaningless question, can we extend the domains of the keyspace, input space and output space of a PRF to be defined over intervals of $\mathbb{R}$?
For instance, let $I := (a,b) \subset \mathbb{R}$ be some interval of $\mathbb{R}$, and $F: I\times I... |
Let's suppose I encrypt an 1MiB plaintext with AES-256 in ECB mode but using different keys for each 16-byte block (I know this is weird but it's just an example).
Remembering that a different 256-bit key will be used for each 128-bit block, so if the adversary wants to break a block, a brute-force in the key space of ... |
At a high level, the Uber assumption states that it is not possible to compute (distinguish) linearly independent elements. In the decisional version, the problem is restricted to $G_T$, but it is unclear whether the linearly independent elements can be from $G_1$.
Here is a simple example:
Let be type-3 pairing $E$: $... |
Let's suppose I take 1MiB of truly random data and split in pieces (seeds) of 32-bytes (256-bits), so I hash each seed with a hash function with the same output digest size (32-bytes/256-bits) and XOR each piece of hashed seeds into a 1MiB plaintext.
The random data is kept secret.
My question is:
Will this scheme have... |
While XOR is used as simple symmetric encryption with arbitrary custom key, what is a simple asymmetric encryption that use arbitrary custom key?
That means I want to be able to set custom private key or public key (in ASCII format).
Expectation:
pub = "mypubkey"
pri = "myprivkey"
msg = "hello world"
encrypted_msg = e... |
I need some help for the following simple game:
An adversary is given a multiplicative group $\mathbb{G}$ and the 4-tuple $(g_1, g_2, g_3, g_1^a \cdot g_2^b \cdot g_3^c)$ where $g_1$, $g_2$ and $g_3$ are random elements from $\mathbb{G}$, and $a$, $b$ $c$ are hidden.
During the challenge phase, the adversary either rec... |
I'm having some trouble understanding the idea behind C_InitToken. I can tell what it does from the standard, but not its purpose.
One of the things it does is to provide authentication of the user as the SO, or initialize the SO's PIN if the token comes from factory. The second half I understand, but the first one see... |
I am trying to find out how to write a security proof for a two-party computation problem.
I have read some examples to write simulators like $x_1 ∧ x_2$ problem and the example in Goldreich's book. I have also read some parts of Lindell's toturial . But I am still unsure about my understanding. I have also seen the pa... |
I am mainly looking to perform this trick for fun. I have access to an API that uses WebCrypto under the hood for encrypt and decrypt methods. I would like to hijack the decrypt method in order to create a deterministic seed.
I have read other articles, and it seems like this trick should be relatively straight-forward... |
I have been investigating libraries that implement operations and protocols involving BLS12-381 curves. I have noticed an absence of libraries that support encryption over (either of) the groups G1 and G2 that are defined by the BLS12-381 curves.
Is there some cryptographic reason that encryption (say, ElGamal encrypti... |
I am recently reading about multi party computation and its various existing protocols. From what I understand, all the arithmetic operations are performed over a field or a ring such that when two secret values, a and b, are used to perform secure computation c = f(a,b), the output of the MPC protocol is c mod P (for ... |
The Schnorr signature scheme was defined originally as $(c, s)$ such that $sG = R + cX$, and the verification process consisted of computing $R = sG - cX$ and then verifying that $c = H(R||m)$ so using only $H(m)$ would not have worked for verification. However, in the verification process of the Schnorr signature vari... |
In theory this is what I have :
Around 10 000 offline machines
Each machine will generate around 10 000 ids
I can program the machine in any way I want, but I prefer a low memory and low cpu
They all will be generated in a short timeframe (1 day)
It should not have id collision
It should not be possible to determine w... |
Suppose that there are $n+1$ parties - $B,A_1,A_2,...,A_n$ that want to share a secret key
The protocol of exchanging is roughly the same as Diffe-Hellman
Chose a group $G$ with an order of $p$ - a prime number and a generator element $g$
Each $A_i$ generates a random number $a_i \in \{1,...,p\}$ and send $B$ the valu... |
Let's say I encrypt a message with some secret and store it in a database. Later, I want to securely share that secret with someone, so that they can read the message as well. Even later, I want to further expand the group of people who know the secret by adding another person.
Basically, I want end-to-end encryption, ... |
In your opinion, is the correlation between the length of the ciphertext and the decrypted text (even if it is approximate) a cipher vulnerability? Or is there a solution to this problem outside of it? After all, if the attacker knows the approximate size of the message, he has some information about what type of infor... |
Assume we have a central issuing authority that sends each participant a share that reconstructs in key $P_k$. I.e. Shamir Secret Share with $2$ out of $N$ format where $N>3$.
This central authority also broadcasts public key $P_a$ so every participant guaranteed to receive same $P_a$.
Is it possible to generate such a... |
They say the security of Diffie-Hellman depends on the factorization of (N-1), where N is the big prime number you feed it.
More specifically, (N-1) itself has to have a big prime factor, such as (N-1)/2 also being prime.
My question isn't about why that's the case or how to tell if it has a big prime factor or not, I'... |
In AES, the MixColumns operation involves a linear transformation from GF(2^8)^4 to GF(2^8)^4. The branching factor for this transformation in the original AES is 4, and it is considered secure against differential cryptanalysis with 4 rounds, where the differential probability falls below 2^(-128).
If we replace this ... |
Assuming I have single-key Even-Mansour with single $2n$-bit permutation in wide-pipe Merkle-Damgård specifically with Matyas-Meyer-Oseas mode outputting $n$-bit hash.
What security can I expect against collisions and preimages?
Am I wrong to expect $2^\frac{n}{2}$ for both?
|
Suppose the circuit is a hash function with the input being the pre-image (private) and the output being the digest (public). If one knows of a collision can they create 2 different proofs that are equal bit-for-bit by inputting the 2 different pre-images that give the collision?
It seems such a SNARK does not exist at... |
This question is relevant for both crypto stack exchange and infosec stack exchange. I thought I'd ask here to get answers from a cryptography perspective.
If two systems use the same public key signature system, is it reasonable to re-use keypairs from one system on the other?
For example, both Matrix and the Solana b... |
In evp.h, BytesToKey() generates the key from the passhphrase, IV and the MD5 digest in order to decrypt information used by the public/private keypair generation using AES-256-CBC. I am trying to isolate all the EVP_* functions into a standalone implementation for an embedded system. Does anyone have the actual functi... |
I'm using ECDH for generating shared key for STM32 MCU. Which encryption/decryption algorithm should I use? I looked at RSA and AES project samples provided by STM32 but where do I provide shared key with message to encrypt?
With the current implementation shared key size is 64 bits.
|
I create this question from here.
I am working on a project with C# backend and mobile apps using Java and Swift.
I found this documentation to use RSACryptoServiceProvider.SignData method to sign using private key.
But I don't have idea on how to verify and decrypt it on Java and Swift.
From my understanding, it's sig... |
According to a Lecture from Lecture notes of a Professor of Purdue University "Diffusion means that a change in any plaintext bit must propagate out to as many ciphertext bits as possible." I can't clearly understand how S-box introduces this diffusion in DES. Can anyone explain with an example? Is it because a change ... |
The prover has $n$ group elements $g_1, ..., g_n$ and wishes to demonstrate the knowledge of the discrete logarithm to base $g$ for each of them, i.e, for each $i \in [1,n]$ she knows some $e_i$ s.t. $g_i = g^{e_i}$. We know that by applying Fiat-Shamir to the Schnorr's protocol, we can get $n$ non-interactive proofs i... |
Andreas Antonopoulos effectively states: an input of 256bits of entropy into PBKDF2-HMAC-SHA512 will ONLY output a 64 byte hash containing ~128 bits of entropy. He states the algorithm essentially ignores the extra entropy going in, and it is "wasted" entropy.
IS THIS TRUE? Can anyone explain why?
Source: (starts at 14... |
Given y = g ^ x is discrete log hard on some finite field, is y = g ^ (kx) also equally secure if the value k is a publicly known value which was randomly selected from a uniform distribution ?
To my understanding, if k and x are independent and chosen randomly, then the security of the discrete logarithm problem is no... |
In a cryptocurrency with privacy e.g., zcash, where does proof generation take place? Can it happen in the client's device every time a transaction is performed?
If it happens in client's device, are there possibilities of malware compromising the privacy?
|
What would be recommended way to make deterministic password based file encryption?
I can use SIV mode, but KDF (like Argon) takes salt for which I could use SIV tag, but I cannot make it because I need key first.
I could use hash of file contents as salt, but that would make it 3-pass. If I would use some other single... |
In Rabin-Miller primality test, let N be the number you're checking for primality. Here N = 78007.
Let m be the number you get after dividing (N - 1) by 2 several times until you can no longer do so. In this case, m = 39003.
The next step is to pick an A, here we pick A = 3.
Now we calculate b0 = Am mod N.
Now, if that... |
I'm reading through a paper called Unconditionally Secure Signatures (https://eprint.iacr.org/2016/739) and to generate keys, the authors select $\epsilon-ASU_2$ functions, such that:
For any $m \in M, t \in T, \vert \lbrace f \in F : f(m)=t \rbrace \vert = \vert F \vert / \vert T \vert$
For any $m_1, m_2 \in M, t_1, ... |
In the realm of secure Multi-Party Computation (MPC) schemes, there exist two fundamental concepts known as the covert adversary model and security with abort. From what I understand, both of these concepts involve situations where if a corrupted party engages in dishonest behavior, the honest parties have a reasonable... |
In these two papers the authors mention the "quality" of a trapdoor
[GPV] https://eprint.iacr.org/2007/432
[MP] https://eprint.iacr.org/2011/501
But the best detail on this matter I could find was "The quality of a trapdoor S roughly
corresponds to the Euclidean lengths of its vectors — shorter is better."
I wonder w... |
I'm following the discussion in the question about RSA and what if we set $p<q$.
So, what if we mistakenly let $p<q$ and proceed with the private keys creations; that is, we pick up $p, q, e$ and derive from them: $dP,dQ, qInv$ (I'm using the CRT key structure in PKCS#1).
So, by trying to create those private-key eleme... |
In https://crypto.stackexchange.com/a/27828/79037, it's indicated that one can "save space" by using something globally-unique, like an application-wide "pepper", together with something locally-unique (e.g, a user-id field, unique per-user). In other words, by simply "deriving" a salt (from some other fields/values/et... |
Problem
Suppose there is an entity with some users. The users are split into subsets (determined by the entity) and the entity needs to create public commitments to these subsets such that only a user can determine which set they are in. The sets need to be some minimum size, $m$.
More formally
Let $U$ be a set of user... |
In Regev's publication "The Learning with Errors Problem", a naive algorithm is given on page 3 that can be used to tackle the LWE problem. This is the statement:
Another, even more naive algorithm is the following: keep asking for LWE samples until seeing $poly(n)$ equations of the form $s_1 \approx . . . $ (i.e., a p... |
Is there any study that has looked into what is the minimum number of ciphertext characters one needs to have to do a reliable frequency analysis?
It would be nice to know the evolution of the accuracy of the analysis as the number of characters considered increases, but I haven't found any well done study.
|
I'm reading Rivest et al.'s "How to leak a secret", but I'm having a hard time understanding step 4 of the generation procedure. This could be because of my own lack of knowledge regarding operations on ring but the following:
makes very little sense to me. How am I supposed to solve this equation? I've tried looking ... |
I am right now studying Pseudo Random Functions. I have a couple of constructions made of a safe PRF F:{0,1}^l x {0,1}^l -> {0,1}^l.
I am unsure of wether these are safe ( in terms pseudorandomness ) or not. I will try and reason. Correct me if I am wrong.
1.) F1 = F(k,x)||k
F1 is not safe, since the concatenation of k... |
Passkey is nice. The math is nice. The tech is nice. https://security.googleblog.com/2023/05/so-long-passwords-thanks-for-all-phish.html
What I still dont see after sooo many hours: what software creates the passkey. User autonomy is important and it is a (private) key question (pun intended). I do not really see this ... |
Do $\exists $ keys $k_1, k_2$ which given any (128-bit) message $m$ are related to each other by being
commutative to each other with $AES(AES(m,k_1),k_2)=AES(AES(m,k_2),k_1)$ $\forall m$ and generally $AES(m,k_1) \not= AES(m,k_2)$
or $k_2$ is equal to applying $n$-times $k_1$ with $AES^n(m,k_1)=AES(m,k_2)$ with $AES^... |
My understanding is that an elliptic curve $E$ over a finite field $\mathbf{F}_q$ has a bit security of $\sqrt{q}$ assuming Pollard rho or Baby-step giant-step. In this thread, it is explained that the field $\mathbf{F}_{2^{256}}$ has a bit security of $128$, but the field $\mathbf{F}_{2^{256^{2}}}$ supposedly only has... |
It seems like every CCA-secure KEM1 has some sort of check that the decapsulator performs. Sometimes failure will result in rejection ("explicit rejection") or the decapsulator will simply return a random value ("implicit rejection", like in Fujisaki-Okamoto without aborts). But in any case, the decapsulator knows when... |
The Python secrets module claims to produce cryptographically secure random numbers. I did some research on which random number generator is used when you call the secrets module on Windows. I found the following:
->secrets uses random
->random uses os.urandom
->os.urandom uses _PyOS_URandom() from Python/bootstrap_has... |
In a course I'm taking the following question came up:
A 51% attack means:
A. 51% of the nodes are bots
B. 51% of the nodes are hackers
C. 51% of the nodes are offline or disabled
D. 51% of the nodes agree on something
I had answered D, but the correct answer was given as B.
As far as I am aware, I be... |
If both communicating sides end up with the same secret 3000-bit key, is it enough to XOR each byte of the messages with each byte of the secret key to make it secure?
Wikipedia says it is, but I wanted to ask if this is still the case nowadays.
That would mean each message can be up to 375 bytes in size, so that each ... |
There is this cool paper https://eprint.iacr.org/2017/395.pdf exposing a side channel protected implementation of keccak, in particular Domain Oriented Masking for the Chi function.
The Chi function is a 5bit S-Box, so can also be seen as a lookup table of 32 5bit values.
My question is, in an hardware implementation w... |
If we talk about the security of public key encryption in Regev's lwe system, if attacker would have knowledge of $(u,u'):[\mathbf u=A\mathbf r, \mathbf u'=\mathbf b^t\mathbf r + \mu q/2, \mathbf r\in\{0,1\}^m]$ and $\mathbf b$, then value of $\mathbf r$ in $\mathbf u'$ can be guessed easily by the knowledge of $\mathb... |
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