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I'm trying to implement EC scalar multiplication in the fastest way possible (but still with a good curve) on a GPU.
I'm specifically looking to implement it based on https://github.com/Chair-for-Security-Engineering/ecmongpu and trying to use other curves like Curve25519 (or Edwards25519, I believe it's a representati... |
I'm still reading about the Padding Oracle attack and Side Channel attack that can be performed to decrypt cipher text encrypted with CBC though it's still not clear to me.
But base on my little knowledge and understanding, all of this attacks can only be performed over the internet right???
Let's say I created a progr... |
I want to implement the following algorithm, but don't know what tools to use.
D - data
I generate some universal value for D - Y
I generate some random key - K, get a hash of D by this key - H
I want to be able to have a function - F: F(Y, K, H) = true if H is correct and false otherwise.
The main goal: to prove the... |
I am currently trying to do the cryptopals challenge 62, breaking ECDSA with biased nonces, with the help of those two links (1 2) that describe accurately the attack. However, after around 15 hours, I still can't have it working, and I have absolutely no clue where I made a mistake.
Here is how I did it (using Python ... |
Assume the following scenario:
Alice has access to 32 bytes of true randomness $s$.
Alice hashes $s$ with SHA-512, and uses the resulting hash as the secret $d_{A}$ for Ed25519. Assume number-clamping and so on are correctly implemented.
Alice hashes $s$ with a different hash function, say BLAKE-2, or hashes $s$ two t... |
Masking is the process of replacing operations (internally to some cryptographic algorithm) on intermediate values with operations on secret shared values. Then, even if some number of these secret-shared values leak (say due to various side-channel attacks), one can maintain security (due to the information-theoretic ... |
To answer my question, imagine a device that has some sort of secret(s) (stored on a crypto coprocessor), that is encrypted with some sort of symmetric encryption (like AES).
If to make this device secure, I would keep the key separate, in a smart card for example.
Then when the smart card is inserted into the device, ... |
I'm reading "On the implementation of pairing-based cryptosystems".
It states that $E(\mathbb{F}_{k^q})[r]$ is isomorphic to the product of $\mathbb{Z}_r$ with itself.
$E(\mathbb{F}_{k^q})[r]$ is the set of $r$-torsion points, which means all points, $P$ where $rP = O$ (I think).
Ok. Let's test this with $r = 2$. We kn... |
Suppose $G_1, G_2$ are the base points on curve25519 and spec256k1, respectively. Point multiplication means to compute $kG_1$ and $kG_2$.
Then which curve is faster?
|
Consider a service $S$ that receives hashes of documents from a number of providers. If two hashes match, it notifies the providers. We do not want anyone at the service to be able to identify the documents. However, the document space is actually quite small (~billions) so a dictionary attack is possible.
One solution... |
Could someone please tell me where I can find the source code of the Coppersmith method univariate written in C with the GMP library?
to be fair I will explain how I will use it for factoring
reference
https://www.academia.edu/48848013/Lepore_Factorization_nr_88
Let's take the example N=1763 of Factorization nr 88 Part... |
This question is linked with this question (stackoverflow) where I asked about a specific implementation detail of Python's random number generator (Mersenne Twister). Here, I have a slightly different focus. Feel free to close, but I could not find a similar question which exactly answered my question
In a PRNG what ... |
I'm finding the algebra behind cyclic codes somewhat tricky. The starting point is easy enough: $C\subseteq \mathbb F_q^n$ is cyclic if any cyclic shift of a codeword $c\in \mathbb F_q^n$ is still in $C$. Then I got hit with this: cyclic codes correspond to the ideals of
$$\mathbb F_q[x]/(x^n-1). $$
Now, I have some ba... |
Section 4.1.6 of https://www.secg.org/sec1-v2.pdf describes a technique for recovering public keys from ECDSA signatures.
I guess Ethereum uses this. Like if you want to validate a particular transaction I guess you recover the public key and then verify that it matches the "address".
My question is... are there any o... |
To carry out Elliptic Curve Cryptography between parties, are all elliptic curve equations considered to be in the form $\bmod p$?
For example, the $secp256k1$ Bitcoin curve of the equation $y^2=x^3+7$ uses $\bmod p$, where $p=2^{256}-2^{32}-977$.
|
I've seen that OFB is considered as a block cipher mode. But could we consider it also as a family of stream cipher?
|
Two people want to come up with a random number. They don't trust each other nor any third party. What are the known solutions to this problem?
I am a quantum cryptography student and am currently working quantum random number generation. Any solutions, either classical or quantum are welcome.
EDIT
Ok so here's what I ... |
Here is my understanding of the concept of security games. I bolded some parts that I am not sure about.
A cryptographic object is formally defined by its algorithms and what security notions it achieves. Such notions capture an adversary’s power and show how the adversary may "break the cryptosystem". "Breaking a cryp... |
I'm reading Pairings for beginners by Craig Costello.
I'm trying to understand this example of (what I think) is the Pohlig–Hellman algorithim (on page 31 of the book).
Consider $E/\mathbb{F}_{1021}\,:\,y^2=x^3+905x+100$ with group order $\#E(\mathbb{F}_q)=966=2\cdot3\cdot7\cdot23$ and generator $P = (1006,416)$. We a... |
I have been reading the book Mastering Bitcoin written by Andreas. It was the process of compressing public keys that hurt my mind. Specifically, a public key after being generated from a private key fundamentally comprises the resulting coordination of x and y.
The book said that since y value can be gained from x via... |
I am reading this explanation of zkSnark written by Maksym Petkus - http://www.petkus.info/papers/WhyAndHowZkSnarkWorks.pdf
From Section 3.5
Because verifier can extract knowledge about the unknown polynomial
$p(x)$ only from the data sent by the prover, let us consider those
provided values (the proof): $g^p$, $g^{p'... |
Suppose I want to encrypt $mssg$ using One-Time-Pad, and I want the $mssg$ to be encrypted twice.
Once with $k_1$ and second with $k_2$
Is it still possible to detect my $mssg$?
lets say:
$c_1 = mssg \oplus k_1$
$c_2 = mssg \oplus k_2$
$c_1 \oplus c_2 = k_1 \oplus k_2$
|
Imagine there is 256-bit uniform input from CSPRNG. Suppose there is a curve like secp256r1 whose curve order is slightly less than 256 bits.
We cannot just mod(input, curve_order) because it will introduce modulo bias. What if we trim 256 bits to 255 bits which is less than curve order? Then all values within 255 bits... |
I was doing some introductory challenges at CryptoHack and one of the challenges, more precisely it was Favourite Byte, XOR with a single byte.
I did my solution with XORing given string and single key iterated over 256 integers till I find something that looks like "flag".
Then I looked for submitted solutions and on... |
Handbook of Applied Cryptography gives two resources for the OFB mode
1980 FIPS 81. This doesn't give any references, unlike NIST.
1983 ANSI X3.106, unfortunately pay-walled.
Who is the inventor of the OFB mode of operation?
|
Example:
I send an email from address@domain1.com to address@domain2.com
Using only the email I received in address@domain2.com, I'd like to prove to a 3rd party that I also own address@domain1.com
Edit: assume I don't own neither domain1 nor domain2, just have email addresses in both (gmail and hotmail, for example)... |
I've been trying to improve my understanding of elliptic-curve cryptography; I'm currently trying to understand the extent to which curves are interchangeable.
Examples of curves: P-256, Curve25519
Examples of algorithms: ECDH, ECDSA, EdDSA
Of the curves I listed, I've read that both are used with ECDH, but I've only ... |
I am following the discussion in Koblitz in the second paragraph in the RSA section (page 94 on my edition).The goal is to show that knowledge of an integer $d$ such that $$m^{ed}\equiv m \mod n$$ for all $m$ with $(m,n)=1$ breaks RSA.The problem is that I'm no mathematician and I need some help to untangle myself at v... |
I think I have an understanding of the Pohlig-Hellman attack on elliptic curves. From page 31 of Pairings for Beginners:
Find the group order $\#E(\mathbb{F}_q)$, call it $n$, and factor it. Example: $966 = 2 \cdot 3 \cdot 7 \cdot 23$
For each prime factor $p_i$, above: multiply the generator $P$ and target point (not... |
Let's suppose I encrypt something with CTR mode and keep the key and IV secret.
Does keeping the IV secret together with the key increase strength of encryption?
|
How does this code calculating the AES S-Box work? I don't understand the overall calculation procedure. Code is attached below:
function generate(irreducible_poly){
try{
p = parseInt(eval(irreducible_poly.replace(/x/g, '10')), 2);
} catch(err){
console.log('Irreducible Polynomial invalid');
... |
I'm looking at a protocol which adds the IV (used for the encryption) into the AAD.
If the IV (which is part of the message) was incorrect, decryption would fail anyway.
Why is it useful to add the IV to AES256-GCM's AAD?
Is it actively harmful?
|
Suppose I have a basis $B$ of an $n$-dimensional lattice $L\subseteq\mathbb{Z}^n$ and $B$ has $n$ vectors. Now I take another $v\in \mathbb{Z}^n\setminus L$ and I define a new lattice $L'=L+\mathbb{Z}v$. The set of vectors $B':=B\cup\{v\}$ generates $L'$, but since $L'$ is $n$-dimensional, it's rank is at most $n$, so ... |
In RSA, if we use Square and always Multiply algorithm in decryption, how does decrypting the ciphertext $c=n-1$, while our public key is $(n,e)$, cause the private key $d$ to reveal due to side-channel attack?
|
Motivation. There is a fast approximation to conventional multiplication. It conceptually works like long multiplication except for the fact that the carry is discarded instead of applied to the more significant position. Hence its name: carry-less product. One use is to improve the speed of applications doing block ci... |
In hash functions, $h(m) = h(m_1)$ is called collision and is very undesired that they are feasible to find as it undermines hash security. However, is there essentially analogous concern in encryption like block ciphers (AES-256) or RSA? If there is plaintext key pair $m,k$ that yields some ciphertext, and there exist... |
I am looking for performance measurements in cycle counts for an implementation of the elliptic curve Diffie-Hellman for curve, ed25519. Ideally, the cycle counts should be for the M4, so that they are comparable with the pqm4 benchmarks: https://github.com/mupq/pqm4. Are there any measurements that can be compared to ... |
I am aware that there are weaknesses in ECDSA when reusing NONCE and I am aware that there is a lattice attack on ECDSA.
Are there other ways to attack ECDSA when one private key has made more than 10 million signatures?
I'm interested in the secp256k1, secp256r1 elliptic curve parameters. Under what conditions can the... |
How to generate constraint on right shift bitwise operator in the circom circuit language?
I'm trying to do the following:
pragma circom 2.0.0;
template MAIN() {
signal input v;
signal output type;
type <== v >> 5;
}
component main = MAIN();
I'm getting the following error:
error[T3001]: Non quadratic... |
Let $p$ and $q$ are Sophie-Germain primes such that $p=2p'+1$ and $q=2q'+1$. Also let $n=pq$ and $n'=p'q'$. In Section 8.2.1 of this paper, the internal direct product of $\mathbb{Z}_{n^2}^*$ is shown as
$$\mathbb{G}_{n}\cdot\mathbb{G}_{n'}\cdot\mathbb{G}_{2}\cdot T$$
where $\mathbb{G}_{\tau}$ is the cyclic group with ... |
Don't know a lot about cryptography, so need some help on this.
I would like to use a SHA256 string as a unique id in my database for users, but scaling that would be difficult.
Is it possible to convert a SHA256 string to be a shorter unique version, that would not collide (or collide very rarely)?
Could passing the S... |
It is a well-known fact that knowing the nonce used in signing the ECDSA signature allows the private key to be computed easily from that signature. If I understand it correctly, this nonce is a positive integer of finite size, so there aren't that many possibilities compared to trying to brute-force the private key di... |
I have elements from $\{0, 1\}^{n}$ (range of a hash function)
The master $A$ can have any subset of this range.
There are clients that each have a subset from the space, too.
I want to make sure that the union of the clients' sets is equal to the master set
The communication should be as least as possible.
The elemen... |
Let's say we're using the Ed25519 curve, and we're computing a Diffie-Hellman shared secret EC point $S$ by scalar multiplication of scalar $a$ with EC point $B$.
Is there any way of partially calculating at least a few bits of $S$ without completing the full scalar multiplication process?
The goal is to be able to com... |
F: {0,1}^λ → {0,1}^2λ is a secure pseudorandom generator, it says that λ is a security parameter, what does that mean?
|
Chaskey (https://eprint.iacr.org/2014/386.pdf) is a a secure, compact and efficient MAC for embedded systems and has won many benchmarks. It is built using an Even-Mansour block cipher. This block cipher XORs a plaintext with a key, applies a public permutation function, then XORs the result with the same key to create... |
Some block cipher modes of operation use only encryption processes, such as CFB, OFB and CTR.
If doing multiple encryptions using them, will these encipherment schemes be vulnerable to Meet-in-the-middle attacks?
I'm asking this because there is no decryption process in these modes, so I can't imagine a Meet-in-the-mid... |
Is it possible to include a hash digest visibly in an image, such that the hash of the image itself is that same digest?
When we draw the text of the hash in the image, we will of course change the hash of the image at the same time, because as we know, small changes to the input of a hash function produce significant ... |
Given a safe prime $P$ and a generator $g$ which generates all values from $1$ to $P-1$ with
$$g^n \mod P$$
1.) Is there now a function $f$ which assigns a unique value to a range of members
$$f(g^{i-a_i},...,g^{i+b_i}) = f(g^i) = v_{ia_ib_i}$$
2.) Given such a unique value $v_{ia_ib_i}$ the offset to the next $g^{q_i}... |
I am really stuck with the following question:
$G: \{0,1\}^\lambda \to \{0,1\}^{2\lambda}$ is a secure pseudorandom generator, and $\lambda$ is a security parameter.
Is the following a secure pseudorandom generator?
$$G'(s_1,s_2) = (s_1 \oplus 1^\lambda, G(s_1))$$
What confuses me about this is the use of the security ... |
I think I've understood properly, but I want to make sure as this will involve money.
Password requirement is a minimum of 16 characters and must contain one of each [Upper, Lower, Digit, Other]
My salt is Crypto RNG generated 64 bytes
I convert salt to Base64 (without the trailing ==)
I then get the UTF8 bytes of con... |
Is it possible to do a key agreement with ECDH ephemeral-ephemeral without requiring an initial handshake first?
Is it possible to have the key agreement in the same message as the encrypted data with ECDHE?
I know this is possible with ECDH ephemeral-static but that does not have perfect forward secrecy. And with ephe... |
Fully Homomorphic Encryption lets us operate over encrypted data. Is there something analogous that let us operate over plaintexts directly, without knowing the circuit?
For example, let's say that I store AES of the user's password, and I want to be able to change the user's password to password +1 at my will without ... |
I am trying to understand the following pseudorandom function constructed by Banerjee, Peikert, and Rosen in this paper, assuming the hardness of LWE. Consider the following LWE/LWR based pseudorandom function:
$$F_{A, S_1,\dots, S_k}(x_1,\dots,x_k) = \left\lfloor A\prod_{i =1}^k S_i^{x_i}\right\rceil_p,$$
where $A \in... |
How is the multiplicative inverse calculated in the following? Please explain with details.
Note: I understood how polynomial value 283 is calculated.
|
I'm reading about lattice based cryptography. In my reading I read of gram–schmidt orthogonalization. Which allows for turning a bad basis into a good basis, or at least an orthogonal one.
Now I'm reading that in the GGH encryption scheme a good basis is used as private key and a bad basis is used as public key.
Howeve... |
I want to use a secret sharing scheme, where every player $i\in N$ has to share a pair of secrets $(l_i,\nu_{l_i})$, where $l_i$ is a unique code (positive integer) for every player, but $\nu_{l_i}$ is a secret like a statement. For example when player $i$ reports to the other players $\nu_{l_i}$ is like making a stat... |
I'm looking for the simplest and most inexpensive hash with the following properties:
Input: A 32-byte Curve25519 EC point containing approximately 125 bits of non-uniformly distributed entropy (created as a result of an ECDH exchange).
Output: 1 byte containing 8 bits of entropy, uniformly distributed.
|
JavaCard 3.1 introduces this KDF as part of this release. Can someone help me in understanding this topic clearly? (KDF ANS X9.63). I need some parameters informations. What is shared secret and shared Info, differences between them, how they are generated etc..
How to validate and corresponding code in Java ? to asser... |
When we use a secret sharing scheme we usually want to reconstruct the polynomial function $p(x)\in\mathbb{Z}_q[X]$ with the Lagrange interpolation method and then compute $s=p(0)=a_0$. However, the secret $s$ is just a number and usually what we have as a secret could represent a private information that is a whole st... |
I am reading this explanation of zkSnark written by Maksym Petkus - http://www.petkus.info/papers/WhyAndHowZkSnarkWorks.pdf
The example used here is that there is a polynomial of degree 3 which the verifier knows has roots 1 & 2.
The whole polynomial is $p(x)$
The target polynomial $t(x) = (x-1)(x-2)$.
The 3rd root ... |
A fast alternative to conventional multiplication is the carry-less product. It works exactly in the same way as the multiplication on the countable set of binary polynomials $\mathbb{Z}_2[x]$. We can identify any non-negative integer with a binary polynomial using the integer's binary representation (e.g. $13_{10} = 1... |
What are the time and space complexity of the AES S-boxes? Could someone please explain how these are determined?
|
Let's say I have a master key and want to use it to derive new keys to use for encryption, using HKDF. I'm a bit confused regarding the use of salt though. I have seen other posts about it here but I still don't fully understand when/if I should use it.
Scenario:
A creates a MasterKey and shares it with B, C, D. A deri... |
Assuming the alphabet of capital letters, if an affine linear cipher $v\to Av+b \bmod 26$ with block length $3$ maps plaintext ENCRYPTAGAIN to ciphertext BLOCKCIPHERS, what are $A$ and $v$?
I referred a paper, there it is given as like this, *As an example, suppose we want to take our block-length to be 4. This means t... |
I am reading this explanation of zkSnarks written by Maksym Petkus - https://arxiv.org/pdf/1906.07221.pdf
In section 4.5, the pdf explains how to represent the following operations
$a$ x $b = r1$
$r1$ x $c = r2$
as $l(x)r(x) - o(x)$ where $l(x)$ is the left operand polynomial, $r(x)$ is the right operand polynomial... |
As I understand it from web conference hearsay, the Kyber and Saber entries to the NIST post quantum cryptography competition have been subject to a patent claim from the CNRS. The creators of the schemes wanted their cryptosystems to be public domain and opposed the legal claims based on mathematical grounds, which wa... |
Consider a pairing $\mathbb{e}: \mathbb{G}_1\times \mathbb{G}_2\longrightarrow \mathbb{G}_T$ with generators $g_1$, $g_2$ for $\mathbb{G}_1$, $\mathbb{G}_2$ respectively. The groups $\mathbb{G}_1$, $\mathbb{G}_2$, $\mathbb{G}_T$ are of some prime order $p$.
For a trapdoor $s$, let $[g_1,g_1^s,\cdots,g_1^{s^N}], [g_2,g_... |
I just designed my own padding function and came up with a potential problem that could harm the security of encryption. After I fixed that flaw, I found out that the PKCS7 standard padding should be also vulnerable to a known-plaintext attack. Please correct me if I am wrong at any point.
PKCS7 is filling each padded ... |
My question is kind of related to this topic: Can we prove possession of an AES-256 key without showing it?
But I couldn't figure out how to apply it to my problem.
Description:
Lets say I have a hardware chip, and I want to prove it has not been copied. The chip can store a AES-128 key and can do some encryption with ... |
I try to understand invalid curve attack and small subgroup attack.
The lower 3 bits of a ed25519 private key are cleared to be a multiple by 8.
So an attacker is unable to gain any information using a public key of a smaller subgroup or on a invalid curve.
Does this mean a check that a public key is on the curve befor... |
I'm having difficulty decrypting a secret message as a part of a CTF and I was wondering how could I decrypt an encrypted text that has been encrypted with pycrypto RC4 and when the first 8 characters of the plain text secret are know. Here is the secret that is in the code:
secret = b'Sff3az11oTAChXcnaCvx2i/P7pZWLMPWX... |
I read the Argon2 specification.
It says in 3.1 (Page #5):
Secret value K (serves as key if necessary, but we do not assume any key use by default) may have any length from $0$ to $2^{32}\text{-}1$ bytes.
Let's suppose I want to convert Argon2 into a block encipherment, I provide an 8192-bit key (1024 bytes) and provid... |
Is the following problem a known cryptographic problem?
Find algorithms for functions $f$ and $g$, such that
$$
f(x, \alpha_{enc}) \rightarrow \beta_{enc}\\
g(x, \alpha_{dec}) \rightarrow \beta_{dec}
$$
where $x$ is some data of $n$ bits, and $(\alpha_{enc}, \alpha_{dec})$ and $(\beta_{enc}, \beta_{dec})$ are (public, ... |
I read it once on a page (I don't remember the link and I coundn't find it) that said about a cascade of AES with two 256-bits keys and that it provides 384-bits of security. Maybe not 512-bits of strength because of AES-256 block size of 128-bits.
This left me doubts.
Let's suppose I encrypt something two times using ... |
I'm writing an application where both encryption/decryption and signing/verification are needed, and I choose X25519 as a key agreement algorithm which will produce a key for encryption, and ECDSA to sign messages.
Key generation: I generate a curve25519 private key from a mnemonic (so I have kind of a random 32 bytes ... |
I can see what I think should be the public key in the Details tab for StackOverflow's certificate (see screenshot below).
However, it is 2160 (num of chars (540) multiplied by 4 = 2160) bits long, not 2048 as it specifies.
When I view the certificate details using openssl in cmd, I can see a smaller version of the pub... |
I'm building a small library for Schnorr Signatures and the Oracle DLC, the key passage is:
s_i G = R - h(i, R)V
R = k G; G generator, k a nonce
h(i, R) is the hash of the message i (i is one of the outputs that will be signed by
the Oracle)
V is the public key of the Oracle (= v G)
The "add" and "multiply" operation... |
dm-crypt in Linux uses 512-byte blocks (disk sectors) having sub-blocks of encrypted plaintext for block cipher modes that are non-parallelizable:
"With the usual modes in cryptsetup (CBC, ESSIV, XTS), you can get a completely changed 512 byte block for a bit error. A corrupt block causes a lot more havoc than the occ... |
Let's suppose I take a cipher with key size equal to the block size (Threefish).
I XOR a random block in the ciphertext, encrypt with a key, XOR another random block, encrypt again with another key and XOR a third random block. It would be XOR->Encrypt->XOR->Encrypt->XOR.
/\ Is this scheme vulnerable to Meet-in-the-mid... |
I'm referencing RFC-6090 for a hobbyist implementation of elliptic-curve cryptography.
I've opted for an exception-free (the answer pointed me to this paper) formula for point addition and thought - I only use point doubling with generator points and validated public keys, I can do with an efficient but not-very-versat... |
I've exported the root CA cert (ISRG Root X1) used by StackOverflow's digital certificate, as a DER encoded binary X.509 (.cer) file and used openssl in cmd to find out the modulus/exponent:
openssl.exe x509 -in C:\Cert.cer -inform der -text
I then did the same thing for the next certificate in the chain which is cal... |
let $(\mathbb{G},q,p)$ be a group $\mathbb{G}$ with prime order $q$ and generator $g$. Assume that CDH is hard relative to this setup (Namely, given $(g,g^a,g^b)$, it is hard to find $g^{ab}$).
Now consider the following: for a probabilistic-polynomial time adversary $\mathcal{A}$, and given $(\mathbb{G},q,p)$, choose ... |
Is it possible to have a homomorphic mapping from $F_{p^n}$ to ${\mathbb Z}_{p^n}$ that preserves both the add and multiplication operators?
Or if we relax requirement, can we have a homomorphic mapping from the multiplicative
group $F_{p^n}^*$ to ${\mathbb Z}_{p^n}^*$ which preserves multiplication?
|
I was wondering where did affine cipher get its name from. I am curious to know its origin and how it is related to the cipher. The Affine Transformation page on Wikipedia states:
In Euclidean geometry, an affine transformation, or an affinity (from
the Latin, affinis, "connected with"), is a geometric transformation
... |
I have a question about how RSADP/RSAEP are defined (in RFC2437 https://datatracker.ietf.org/doc/html/rfc2437#section-5.1.2):
RSADP (and RSAEP) are described with the same limits for the message (m) and ciphertext (c), namely 0 <= m < n. In this case the modular exponentiation primitive assumes padding has already occ... |
I am trying to understand the benefits of using blockchain technology in document certifications such as university diplomas. I would like to know the difference between digital certification and blockchain certification. To be more specific, the digital certification that I am considering works as follows. A trusted c... |
I have an arbitrary string. I want to know how to implement a hash function $H: \{0,1\}^* \to \mathbb F_q^n$ which takes arbitrary strings to an element of $\mathbb{F}_q^n$. Here $\mathbb{F}_q$ denotes the finite field of order $q$.
Edit: $q=256$
Edit 2: $\mathbb F_q^n$ simply means $n$ dimensional vector space over $\... |
do you know anyone who works in finance/banking who knows about encryption of financial documents? This is for an academic research paper, whereby I would be interested to research further information about encryption that was used in financial documents i.e. before David Chaum's blind signature research that developed... |
Can we assume without loss of generality that the verifier for non-interactive zero-knowledge proofs in the common reference string model is deterministic, or does random randomization add extra power?
|
Let $f : \mathcal{U}_{2\lambda} \to \mathcal{U}_{2\lambda}$ be a OWF, and $G : \mathcal{U}_{\lambda} \to \mathcal{U}_{2\lambda}$ be a PRG with $\lambda$-bit stretch. Establish whether the following function $f' : \mathcal{U}_{\lambda} \to \mathcal{U}_{2\lambda}$ is one-way or not:
\begin{equation*}
f'(x) = f(G(x) \... |
FIPS 140-2 is a standard which handles cryptographic modules and the ones that organizations use to encrypt data-at-rest and data-in-motion. FIPS 140-2 has 4 levels of security, with level 1 being the least secure, and level 4 being the most secure.
Google Cloud has a lower level (level 3) compared to IBM Cloud (level ... |
I found there are two perplexing and related concept "Collision Resistance" and "Computation Binding in Commitment" in cryptography.
I found the wikipedia's explanation is confusing. And no resources clarify their difference
Especially, I found I can't differentiate the two concepts' common ideas which is given certain... |
The PRP/PRF switching lemma is usually denoted as follows:
I understand the proof of this version of the bound $\frac{q(q-1)}{2^{n+1}}$ and the game-playing technique behind it.
However, I came across a different version of this lemma recently, which is used more often in papers. It is denoted as follows:
This versio... |
Using
montgomeryX = (edwardsY + 1)*inverse(1 - edwardsY) mod p
it is possible to transport an Edwards curve point (Ed25519 public key) to the Montgomery curve. Does it have any side effects if the Ed25519 public key is not valid, in case of a small subgroup or invalid curve attack for example?
And if yes, what would b... |
Is AES GCM without GMAC vulnerable against bit-flip attacks? Let's assume the plaintext is known for some reason (e.g. it can be guessed). In my opinion, I can flip bits in the ciphered blocks and can so generate a plaintext, which is flipped at the same position. So it would be easy to change 0x01 to 0x00 in the plain... |
I'm aware we can quantify privacy with ε-differential privacy (ε-DP). But when we apply DP, how do we actually select the value for ε ? Are there some rule-of-thumbs? Is it decided case-by-case basis? In general, how do we decide we've enough privacy when using some algorithm that satisfies ε-DP definition?
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I considered Extendable-Output Function (XOF) with a random seed but it seems I would have to specify the output length at the start and store the entire output. I don't know how many bytes I will need in advance, and I don't want to store a very long string.
I also considered some ad-hoc stateful construction using XO... |
Outside of professional carrier, I often stumble upon a need for a unique password for exp. for local database, game server, or on tons of, not so important, websites.
I came up with an idea to write a deterministic password generator for myself, which takes a tuple:
master password
header for exp. just a word "pinter... |
I have read some PIR papers, but I find the related discuss of PIR framework was in 7 years ago.
So could somebody tell me，what is the mainstream PIR method in industry now？
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