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4.25) Let F be a strong pseudorandom permutation, and define the following fixed-length encryption scheme: On input a message $m ∈ \{0,1\}^{n/2}$ and key $k ∈ \{0,1\}^n$, algorithm $Enc$ chooses a uniform $r ∈ \{0,1\}^{n/2}$ and computes $c:= F_k(m∥r)$. (See Exercise 3.18.) Prove that this scheme is CCA-secure, but is ... |
In Discovering faster matrix multiplication algorithms with reinforcement learning (Nature, 2022; lightweight intro), the authors used reinforcement learning (an artificial intelligence technique) to devise a new, slightly faster matrix multiplication algorithm.
Could a similar technique work towards a better multiple-... |
Encryption schemes typically are built on the idea that even if a man in the middle attacker knows exactly what kind of encryption you're using, they cannot decrypt your messages without the key.
There are a number of different mechanisms for two users to create or exchange keys without a man in the middle being able t... |
In a Sigma-protocol, the steps are (1) commitment, (2) challenge, and (3) response. In general, the prover has a statement and witness that they can use to compute the commitment step. But in some cases (like Schnorr or equality of two discrete logarithms) the prover doesn't use the statement or witness in the first st... |
Why physical random number source can be weak? I see two kinds of problems:
it is hard to control it and make it resistant to some unwanted bias, but also deliberate attacks,
it has normal distributuon, while we usually want to have uniform distribution (that's why we use randomness extractors or KDFs).
Can anyone el... |
I'm looking at scheme on Wikipedia:
https://en.wikipedia.org/wiki/Merkle–Damgård_construction
And it looks like function f takes two inputs. So do we have to use in this scheme OWF which can take two inputs or maybe we can somehow combine IV with message block, for example by xoring them? Then f can technically take on... |
I wonder if there is a more efficient polynomial multiplication than Karatsuba over the finite field $\operatorname{GF}(2^n)$. Brief research on this topic gave me a few results on fast multiplication on $\operatorname{GF}(2^n)$ using a polynomial over $\operatorname{GF}(2)$, however, it was hard to find a fast 'polyno... |
Assume I create a hash using SHA-256 and then take only the first 160 bits of the hash, as the result. is the result more cryptographically secured than SHA-1? Or are the two algorithms equally secure except for the hash size? (for example in terms of uneven distribution of the hashes and other means that determined th... |
I was asked recently if it is somehow possible to use already existing keypairs stored in HSMs for, e.g. ped-DKG.
Which ultimately led me to the question, which data is actually exchanged between parties when generating a shared key-pair? I was thinking surely there has to be some communication of the parties, e.g. agr... |
When performing homomorphically encrypted computations, when should I use BFV / BGV / CKKS?
It seems BFV / BGV is better suited for integers, and CKKS for floats. It also seems BFV-BGV have some portability. I want to calculate using integers.
How do I understand if I should use BFV or BGV?
I also don't understand why ... |
I recently implemented AES block cipher, encryption side only, to be used in QUIC parsing (QUIC uses GCM mode). There are other modes than GCM that use only encryption: for example CTR, OFB, and CFB.
When implementing the AES cipher encryption side, it occurred to me how everything is done there has to be reversible, s... |
This might be a silly question but I am unable to wrap my mind around it. In Diffie-Hellman can we find $a$ when $A = g^a\bmod p$, given we know $A$, $g$ and $p$?
|
For LWE decryption, Someone told me that If we can bound r⋅e by q/4 then we can retrieve M by checking if this is closer to 0 or q/2
However, how to use tail estimation to derive the relationship between upper limit bound of standard deviation (α) and q/4 ?
Note: There is also upper bound value of sqrt(M) for r, which ... |
In the Blum Blum Shub random number generator, we take two random prime numbers $p$ and $q$ such that both have a remainder of $3$ when divided by $4$. My question is why can't we just take any $2$ random primes? What is significance of having remainder $3$ when divided by $4$ from the perspective of mathematics and se... |
I need a fast linkable ring signatures library, something that is O(log(n)) and n is the ring size.
I read a few papers about these kinds of schemes but I didnt find any implementations of them.
Here are few of the papers I read:
https://reader.elsevier.com/reader/sd/pii/S0304397512009528?token=6FCBA7389B1AF78F2C3B52B7... |
In EdDSA with Ed25519 the algorithm of public key computing is following:
h = hash (privateKey)
h[0] &= 0xF8
h[31] &= 0x7F
h[31] |= 0x40
publicKey = h * B
The questions are
Why is Hashing in Ed25519 key generation needed?
Why are the actions on h bits are needed?
What does the clearing relate to the 31st bit?
|
Can we use a MAC to transform a CPA secure encryption scheme into CCA secure one?
|
The RSA modulus is the product of two $2048$-bit primes.
And the two Public Exponents are both $16$-bit.
I also got the difference between two Private Exponents $\left | d_1-d_2 \right |.$
Is there any way to factorize the Modulus $N$?
|
I have a help recommended high-school project that I'm stuck with. To basically explain the problem: I have an encryption function that is used as the decryption function and I need to reverse it to make an encryption function.
I tried many things but I can't find the proper result. The best I came with was to encrypt ... |
In aggregated BLS Signatures, there's a known attack which allows an adversary to forge a valid signature for a message $m$ knowing only the victims public keys.
Reading about the maths behind it, this justification is done:
After some juggling math around, everything is clear but the middle equality. What allows one ... |
I am not an expert in cryptography and therefore I would like to address this problem to people who have been working on this topic for a long time and thus verify the facts from several sources.
I use Winrar for file encryption because it is most suitable for me, it's fast and I'm already skillful with this program. I... |
In "The Skein Hash Function Family" paper authors wrote:
The MIX/permute structure has been designed to provide full diffusion in 9 rounds for Threefish-256, 10 rounds for Threefish-512, and 11 rounds for Threefish-1024.
How they know it? Is there some rule of designing such structures, which can quarantee some level... |
Let's suppose that we have two parties, $A$ and $B$ that are using a Shamir Secret Sharing scheme with $k=3$. $A$ holds the points $[x_1, f(x_1)]$ and $[x_2, f(x_2)]$ while $B$ holds $[x_3, f(x_3)]$ and $[x_4, f(x_4))]$.
$A$ sends the point $[x_1, f(x_1)]$ to $B$, and $B$ answers with the point $[x_3, f(x_3)]$, so that... |
Background: A cryptocurrency, such as Bitcoin, have a global order of all transactions that is guaranteed to be agreed by all participating nodes. With Bitcoin, this is ensured by making the longest chain win, and that creating a long chain requires performing a lot of computations (so it is not trivial to arbitrarily... |
From RFC 8446 section 4.6.3:
If the request_update field is set to "update_requested", then the
receiver MUST send a KeyUpdate of its own with request_update set to
"update_not_requested" prior to sending its next Application Data
record.
Say I have a client connection that sends things to the server, but ... |
I understand that the end result of a Pedersen Hash (like this one) is a point in an Elliptic Curve.
In the example implementation mentioned above, the input $M$ is split into chunks of 200 bits (the last one possibly being smaller). For each chunk, disconnected/random points in the Elliptic Curve are generated and the... |
I was reading some notes on a naive hash to a group function.
Consider a cryptographic Hash function $$H: \{0,1\}^{*}\to \{0,1\}^{k}$$
Consider a Discrete Log Hard Group $G$ with a generator $g$. We can build a Hash to group function $$HG(a) = g^{H(a)}$$
(We raise $g$ to the numerical representation of the Hash output)... |
I'm having a bit of difficulty understanding how to construct Zero-Knowledge proofs. So given a one-way function $f$ and a secret message $x$ so that $f(x)=y$, $f$ and $y$ being public, how could one construct a simple Zero-Knowledge Proof of Knowledge algorithm proving that one knows $x$?
I think I understand how this... |
Is a random number generated by a CSRNG equivalently secure as the SHA hash of that number? I know that RNGs generate numbers that look random, and aren't necessarily random. For example, in a range of [1, 2^256], number 100 might be picked randomly, but it isn't secure, so it needs to be changed.
However, the SHA256 h... |
I have bumped into this challenge from a well known CTF site. I don't want to make a reference to it because I don't want this to be a hint for anyone. And also to avoid giving out the source code of the challenge I will try to describe the code. The thing is that they provide a small script with a class that implement... |
I have written a mathematical paper in cryptography and I want to publish it but I don't know any professors in the field to collaborate with them. So what should I do and how to get contacts that could help me setting up with this work?
|
I am working out ICAO verification process (biometric IDs), and here is one of their publicly available certificates:
# openssl x509 -in 492F0116.crt -text -noout
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 1227817238 (0x492f0116)
Signature Algorithm: ecdsa-with-SHA256
Issuer: C = GB, O = UKKPA, ... |
I am learning Keccak Hash Algorithm and I am a little bit confused about the Capacity bits parameter. I am trying to understand how we can set the capacity parameters while implementing Keccak in python3.
Example: trying to get a collision in Keccak using Capacity = 0 irrespective of hash size (let's say hash size at ... |
Let's suppose I have a 2MB photo and I want to generate a key from it, and the key should have 2048-bits of size.
A hash function such as SHA3-512 would not deliver a key with with the desired strength.
Is it possible to generate such a key with a hash function having the hash function a maximum digest output/internal ... |
From the literature, STC seems to be the current state-of-the-art for the coding part of steganography. From the description of the method, it appears to me it could be parallelized for GPU. Does developing of STC implementation for GPU even worth it? Are there any existing GPU implementations of STC.
The existing impl... |
I am implementing wet-paper codes (WPC) with randomly generated parity-check matrix $H$, based on this paper. As the wet DCT coefficients, I set DCT coefficients with value 0, or with values 0 and 1 (trying both).
For almost every cover image, the input vector at iteration contains too many wet pixels and the program f... |
I need a chat between two users and I obviously want to make it as secure as possible. I am, by no means, a cryptography expert, so I turn to you guys for some advice.
Because I like the idea of having E2E encryption, I did some reading about the Diffie–Hellman method and the Signal Protocol.
My issue is that this is a... |
I'm new to cryptography and signatures, I've done work that involves a signature model, and now I need to run tests on it.
In this paper [1], a signature model called Linkable Spontaneous Anonymous Group Signature is created.
The algorithm is described in the paper, it is capable of creating signatures for groups of pu... |
How would a proof of inclusion be done here as the number of nodes is odd and some hashes don't have a sibling hash?
Normally you would send the sibling for each level to the client.
Here there are none, is the proof of inclusion not possible here, or do you just send the parent, until you reach a node that has a sibli... |
Apple's Find My technology is described in this Wired article and explains how Apple, or other third parties, are not able to decrypt location data. It mentions how the keys are rotated every hour:
That public key frequently changes, "rotating" periodically to a new
number. Thanks to some mathematical magic, that new ... |
In §2.3.4 of Standards for Efficient Cryptography 1 (SEC 1), the authors define the following step in deserializing elliptic-curve points that were serialized in the format given in §2.3.3 (emphasis added):
2.4.3
If $q = 2^m$ and $x_P\neq 0$, compute the field element $\beta=x_P+a+b x_P^{-2}$ in $\mathbb{F}_{2^m}$, an... |
Is there any use for Fermat's Factorization Method in the world of cryptography? I see that several algorithms are based on it, such as the quadratic sieve and general number field sieve. I understand that Fermat's can be very fast if the factors are close to the square root. Generally RSA moduli have factors that are ... |
So I am a math major who is trying to learn some crypto. However I have some difficulties with some of the probability definitions that are assumed in the cryptography book that I am using at the moment. So here it goes:
Def(perfect security): Let $(E,D)$ be a Shannon cipher defined over $(K,M,C)$ where all these are f... |
I'm very new to cryptography and this may sound so foolish. Often I read quantum computers will brute force keys. Let's assume this is true (does it depend on key length? or on an algorithm? I don't know, let's say they will).
If I have a file encrypted with ChaCha20-Poly1305, or perhaps a LUKS encrypted partition with... |
I've been itching my head over this for a while despite going through the queries related to the topic. Can someone explain me negligible and non-negligible function in a concise way?
As of my naive understanding (correct me if I've the wrong take);
A non-negligible function is one which approaches zero relatively slow... |
I want to estimate when and wether different types of functions provide full or partial diffusion.
I'm trying to understand diffusion of basic operations, like:
addtion,
multiplication,
xoring.
If we change one bit in $a$ how many bits will be changed in average in result $c$ if we do:
$a+b \mod n = c$
If we change o... |
In MITM attacks against the NTRU cryptosystem, we exploit the fact that in the ring of truncated polynomials of degree $n-1$ it holds that $$fg=h\mod q$$ for our secret and public keys $f,h$. The basic idea is splitting $f$ into $f_1,f_2$ such that $f_1+f_2=f$ and therefore considering $$f_1h=g-f_2h. $$This is almost ... |
In the half-gate construction of garbled circuits, is it possible to garble multiple instances of a circuit while re-using certain input labels?
Suppose Alice and Bob would like to compute a function using garbled circuits. Alice will act as the generator and Bob the evaluator.
As usual, Alice generates the input label... |
a zero-knowledge proof is a method by which a prover proves to a verifier that a given statement is true while the prover avoids conveying any additional information apart from the fact that the statement is indeed true
Is there a definition of proof in which the prover conveys no more than X information (where X can b... |
A user of this forum said that the whole entropy of a seed goes to the hashed result if using a counter and also that is suitable for key generation even if the internal state or digest size of the hash function is smaller of that of seed.
Let's suppose I have a seed with an entropy of 512-bits and hash it with a count... |
I have a question in the context of two-party computation and the proof of the security of an MPC. I have looked at some of the beginning parts of this, this chapter 7, and
this But I couldn't achieve my answer.
I want to understand the difference of a malicious adversary with an honest-but-curious one, and to get what... |
I am learning about the concept of two security notions called IND-, which include IND-CPA, IND-CCA1 and IND-CCA2. While I got some grasp understanding about the scenarios between the challenger & attacker for each of these models. I am still not able to comprehend what properties of a security model are required to "u... |
As far as I know Additive Secret Sharing uses a finite field to generate its shares.
The gist of the scheme is that the shares $A_{shares}$ = {$A_1, A_2, ..., A_n$} of a value $A$ on a finite field $N$ can be attained by:
$A\ mod\ N = \sum_{A_i \in A_{shares}} (A_i\ mod\ N)$
If all shares in $A_{shares}$ are positive ... |
It was a challenge from CTF (ended), but I didn't solve it.
p, q = keygen(512)
n = p * q
flag = bytes_to_long(flag)
enc = pow(n + 1, flag, n**3)
So we have module and encrypted flag. We don't know module's factors (p,q). I have tried some ways, search another writeups and read many topics, but I didn't find any inform... |
I know that the Chaotic Logistic map is $x_{n+1}=Rx_n(1−x_n)$. I read some articles about the Chaotic Logistic Map, but some things are not clear. Someone wrote in his article the following: The initial condition $x_0$ for the logistic map is extracted from the string of $256$ bits ($32$ characters) taken in ASCII form... |
In this post the top answer says that for $\mathbb Z_p^*$, $k$, the order of an element $g$, divides p-1. Then it was concluded that this entails we can check if $g$ is a generator by checking if $g^k\bmod p\ne1$, with $k=(p-1)/q$ for $q$ each of the distinct prime factors of $p-1$.
Why does the first claim being true ... |
A user of this forum told about ideal and practical hash functions.
What is the difference between them?
Can someone provide examples of ideal and practical hash functions?
|
I have two servers. A production server with a signed (trusted ca) cert and a test server with a self-signed cert.
How big is the difference between the two handshakes?
Because when benchmarking the two servers the self-signed handles ~90 req/sec where the trusted ca cert ~17 req/sec
The server with the self-signed cer... |
I want to ask 2 questions:
Is GCC's stack canary cryptographically secured?
Does stack canary in general has to be cryptographically secured?
|
According to the following, ecdsa-256 only provides ~128 bit security even for 256 bit private key:
A multi-target attack on 128-bit ECDSA private keys
If the private key has only 128 bit entropy but constant-padded to 256 bit, then the corresponding 256 bit public key is distributed.
Would it provide the same 128 bits... |
Given that H is a collision-resistant hash function from 2n-bit strings to n-bit strings.
How do I prove that Hash is collision-resistant if:
$$\text{Hash}(X_1∥X_2∥X_3) := \text{H}(X_1∥H(X_2∥X_3))$$
|
I'm currently reading the specification of Salsa20 (link). DJB on whether he chooses
"xor-a-rotated-sum" instead of "add-a-rotated-xor" states the following :
Should there be modifications other than xor-a-rotated-sum?
There are many plausible ways to modify each word in a column using other
words in the same column. ... |
I want to AES-GCM some user data that I‘m going to persist in a database. I‘m wondering if I should encrypt individual columns (all with an individual IV ofc) or JSON stringify the sensitive data and then encrypt the whole dataset.
Despite the problem that I need more database space for storing additional IVs, I feel l... |
How can I ensure that person X on website A is the same person who contacts me?
Here is my use case.
On website A I post message asking username X to contact me. Someone send me an email - how do I ensure it is the same person? Website A does not have a private messaging functionality and all posts are public and visib... |
Given $E/K$ defined over a finite field extension $K$, can I find another curve $E'/K'$ and a group isomorphism $\phi: E/K \to E'/K'$, where $K'$ has an extension degree lower than that of $K$?
If $K = K'$ then we speak of isogenies defined over $K$, but I am specifically looking for an isomorphism defined over finite ... |
I have two ETH transactions (both belonging to the same address) that both have the same r value in the transaction signature, is it possible to extract the private key from it?
Details of both transactions below:
address:
0xF55f348c48bd2811a34105899db5fF7C2EBD9934
transaction hash(1): 0x374180005946ef3b1906ee1677f85fa... |
I know that SSL Certificates use a private key on the server side and the public key for verifying it on the client side.
I am wondering, is it the same for Code Signing Certificates?
Or do they just use a single Certificate, signed by the CA, that you use to sign your code with. Or do you sign it with a private key, a... |
I have read that some integers are not appropriate to be chosen as the modulus in an RSA cryptosystem. Some of these numbers are those that, given a modulus $n=pq$, then $p-1$ or $q-1$ do not have large factors. This is due to the fact that there are factorization algorithms that allow this type of modulus to be factor... |
On first glance, the optional customization string for cSHAKE resembles the optional salt input to HKDF-Extract. Indeed, the Noise Protocol Framework initially uses a protocol identifier string as its HKDF salt value (chaining key in Noise), which looks very similar to examples of customization strings given for cSHAKE... |
The MD5 algorithm is no longer considered secure for most applications of a hash algorithm. However, is it safe to initialize a PRNG via a password?
If it is not, how could it be exploited?
|
I am looking for symmetric cryptography algorithms that can be implemented on chips with very few resources (about 256K RAM and 16MHz CPU).
An algorithm that works perfectly in this environment is RC4, however it has multiple vulnerabilities. Are there algorithms that can be implemented in this type of systems that do ... |
RFC 8784 introduces a straightforward mechanism to use a pre-shared key to make modified IKEv2 key agreement resistant to a quantum computer Shor algorithm attack- thus providing a "quantum-safe" information channel. One use of this information channel could be to share keys.
QKD authentication requires a PSK in order... |
This question is related to "Is it safe to initialize a random number generator with MD5?".
But in the context of steganography we don't know which pixels have been selected to hide information. In addition, the content could be encrypted, so we do not know if the hidden information that we extract (with a guessed pass... |
This is not for a production application, but just my exploration to help me understand cryptography.
At the simplest level, I want to design a key-value store for user secrets.
This is exposed over an HTTPS API with usual create-read-update-delete operations supported: send a post request with a body of a sercret, the... |
AES-GCM-SIV takes a 96 bit nonce, like the original GCM. The RFC states that "it is RECOMMENDED to use this scheme with randomly chosen nonces". It uses the random nonce to generate per-message encryption and MAC sub-keys using a PRF based on AES, and claims this construction offers beyond birthday bound security:
Th... |
Let $\mathcal R$ be the ring of integers of a power of two cyclotomic field.
That is, $\mathcal R = \mathbb Z[x] /\langle x^{2^k}+1\rangle $ for some integer $k$.
We denote $\mathcal R / q \mathcal R$ by $\mathcal R_q$. This is a well known setup for ring-LWE.
I think that for randomly chosen element $a \in \mathcal R_... |
I am looking for authenticated key exchange protocols (AKE) based on a generic key encapsulation mechanism (KEM) and providing full/perfect forward secrecy. Optionally, the protocols should offer external anonymity.
The idea is to plug into the protocol an existing post-quantum KEM such as CRYSTALS Kyber or SABER.
My r... |
I have seen a few answers here and elsewhere that say a salt doesn't need to be cryptographically secure randomness but rather just unique since they are stored in the open anyway. I am working on an implementation of PBKDF2 and AES-CBC and reading NIST SP 800-132 Recommendation for Password-Based Key Derivation from 2... |
From the Wikipedia page for DSA(Digital Signature Algorithm) we have the following private/public key generation:
Choose an integer x randomly from [1, q-1]
Compute y := g^x mod p
x is the private key, y is the public key
My question is: How are we sure that there does not exist z != x from [1, q-1], such that y = g^... |
For encryption, we want identical plain-text's to encrypt to unique ciphers, also called Semantic Security.
For Signatures, the plain-text (i.e. message hash) is not a secret. The plain-text, if you can call it that, is publicly known. We don't need Semantic Security. There is no “plain-text”, so to speak. We aren’t en... |
If I had a true random number generator that had a fault where 10-20% of the bits never change (these bits always produced the same value every time the TRNG was called), could I feed the result of the TRNG through a hash function (let's say SHA-256) to generate a unique and secure key?
|
The F5 steganography algorithm hides information in images using binary codes. But when hiding a bit, the affected DCT coefficient becomes zero, it is necessary to hide the same bit again. This is because the receiver ignores DCT coefficients with a value of zero, and otherwise would not be able to read that bit. As th... |
I am interested in a polynomial form of the lattice problem Closest Vector Problem (C.V.P), or in other words if C.V.P. can be ''transferred'' to Ring-LWE.
My idea about this question is that a polynomial form of C.V.P will look like the following:
Let $R = \mathbb{Z}[X]/\Phi_M(X)$ and its residue filed $R_q = \mathbb{... |
While reading A Graduate Course in Applied Cryptography by Dan Boneh and Victor Shoup. There was the next exercise (Ex. 4.2 (b)), let $F$ be a secure PRF over $(K,X,Y)$ where $Y := \{0,1\}^n$ and $|X|$ is super-poly. Define $F_1(k, (x,y)) := F(k,x) \oplus F(k,y)$, prove that $F_1$ is weakly secure even if we modify the... |
I'm having an issue with a key created by the manufacturer of an equipment. Checking the details of the key I've noticed that it's exponent is zero. Is this a valid exponent?
|
Searches here indicate that D/H primes of 2048 bits are "safe"? How do we know that this is true? Using a pathetic retail laptop (Intel N5000 Silver) it's possible to find 60,000 bit primes and test them in about a week! Using a 60,000 bit prime in a custom D/H encryption program, and using the same pathetic retail ... |
I have implemented an authentication scheme using JWT with assymetric keys (RS256). The idea is that (assuming some microservice-based acrhitecture) the authentication service will sign all JWTs with a secret/private key (PRIVATE_KEY) and distribute the public key (PUBLIC_KEY) to all other microservices, so they can ve... |
I am working on problem 2.11 from the book: A Graduate Course in Applied Cryptography by Dan Boneh and Victor Shoup. The problem reads as follows:
Problem 2.11: Let $\mathcal{E} = (E, D)$ be a cipher defined over $(\mathcal{K}, \mathcal{M}, \mathcal{C})$. A key recovery attack is modeled by the following game between a... |
It might be a little dumb: I think it should be possible, if I encrypt a plaintext using the same public key twice, it should be possible to end up with two ciphertexts that for whom the statistical distance is non-negligible.
Specifically, I was exploring a paper which required that the statistical distance between ci... |
I'm new to the topic guys, but as there are literally too many encryption methods out there, too that I could even come up with many ideas of them, how to we actually test/calculate "how secure" an encryption algorithm is?
Do we a standard or a formula that we can use to test security level of encryption algorithm?
And... |
Is it possible to introduce a new signed attribute in the CMS Advanced Signature format (RFC 5126) for a custom data type? I want to include location data from GPS or Galileo and extend CAdES for my thesis.
I would appreciate it if you can provide me with some directions if it makes sense.
|
I'm new to crypto!
The situation is,
Aes-256-cbc encrypted message(including not encrypted iv & salt) is revealed.
We also know pbkdf2 function uses 10000 rounds with sha256.
All we need to decrypt the message is just put all the possible passwords in pbkdf2 function with 10000 rounds & sha256,
and then decrypt encryp... |
I want to distinguish different concepts: Bootstrapping, Modular Switching, and Key Switching. I am also sometimes confused about Evaluation & Relinearization.
My understanding of these concepts are:
Bootstrapping is a method to shrink errors in ciphertext.
Modular switching is just an arithmetic technique to transfe... |
TLDR/End goal
I want to encrypt a tree of data/files so that anyone with the master key K can decrypt everything, key K-1 can encrypt and decrypt anything encrypted with K-1-*, and so on. However, K-2* must not be able to decrypt any of K-1*.
First ideas/initial research
To be quite frank the only way I can think of ac... |
A probable attack for RSA (factorization): how to improve it?
$N=8*G+3$ can be factored if there is a non-trivial negative $k$ such that
$\frac{(N*(9+24*k)-3)}{8}=-6*m^2 $
[to exclude the two trivial solutions $m=\frac{(N+1)}{4}-N*t$ and $m=N-\frac{(N+1)}{4}-N*t $]
given the system
$
\frac{[[8*[\frac{(N*(9+24*k)-3)}{8}... |
Let us say that we have 3 entities: an Issuer I , a user/prover P and a verifier V.
V trusts I but does not trust u
u wants to show that he respects some kind of property (eg. being over 18yo) to V without revealing their whole birth day
V possesses the data that u needs to convince V, eg. using a ZK-proof, but V woul... |
I am struggling to solve this proof.
The goal is to prove that $H \circ G$, which is a composite function $H(G(s))$ can be a pseudo-random generator under some conditions on $H$, given that $G$ is also a pseudo-random generator. Note that $H$ is length-preserving.
However, I can't find a way to prove (using the definit... |
As an amateur, my first encounter with commitments has been in the form of an hash of the committed value, then I have learnt about seeding the hash as blinding technique. Going on I have discovered how useful is the structure induced by Pedersen or El-Gamal commitments and the binding/hiding flavours. All of this to e... |
I have a my own PBKDF2 automated implementation that automatically salts the hash. The output looks like this:
xxxxxxxxxxxxxxxxxxxxxxxx.xxxxxx.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
\-- 24 byte salt ------/ \data/ \-- 48 byte output hash --------------/
Salt is a random byte array
Interations are stored in data
Outp... |
Although many different lattice-based signature schemes exist, Hash and Sign signatures schemes, like [GPV08], are prevalent. On the other hand, it is well known that collision-resistant hash functions may be built out of lattice problems [SWIFFT08]. However, I've never seen a scheme that combines both; why? Such compo... |
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