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I'm creating an application that requires message authentication on the payload of a QR-code. Because of the maximum length of an error-correcting (H) QR-code (368 bits) and the original size of my payload (128 bits), I have to limit the size of the MAC.
This leaves me with several options. I can use basically any HMAC... |
I'm currently trying to implement a PEKS scheme for my master's thesis and got stuck on a check I have no clue how to implement.
The equation looks like this:
$$
\hat{e}\left(P_1, T_3\right)\stackrel{?}{=}\frac{\hat{e}\left(T_1,T_2\right)}{\hat{e}\left(T_1,T_3\right)}
$$
Note: $\hat{e}$ is a bilinear pairing function $... |
i would like to implement a custom Encrypt than HMAC scheme instead of using AES-GCM can anyone share resource to do it correctly . are there any common pitfalls i should be aware of for secure implementation ( i browsed internet but got shady sites like medium.com , i couldn't trust hence asking here , sorry for poor ... |
Problem
I have a central server to store content. A user can create content and control who can decrypt this content. This needs to be secure using E2EE.
How another user knows whether to fetch this content to try decrypt it is out of the scope of this question.
My initial solution
Requirements:
Content must be encryp... |
I am trying to find a good implementation of Merkle Tree generation in Golang, and I need the tree to be resilient to Second Preimage Attack
I have found this standard implementation in the golang docs, but it looks to me like it is susceptible to Second Preimage Attacks, since it only uses 1 hashing algorithm for the ... |
According to video from Dr. Pound, password managers (LastPass in particular) holds encrypted image of your data on their servers and then with master password you authenticate to get encrypted image to client side where decryption is done.
How is this handled when you login to lastpass website with browser?
Is your b... |
Can setting random indexes (and hiding them from the parties) in Shamir's secret sharing solve the colluding problem?
Here, Colluding problem is defined as if the threshold number of fraud parties combine and recover the secret without the knowledge of the dealer and Indexes are the x-coordinates of their respective sh... |
The Skein hash function family defines stream cipher and message authentication code modes of operation.
While these two modes can be used together to perform authenticated encryption with associated data, there is no mention of a single mode of operation to do this.
Ideally, a mode would be defined that would support ... |
I'm searching for ways of replacing a Merkle-tree with something more space-efficient.
I don't need any kind of authentication embedded - the accumulator value can be signed via a separate procedure.
Thanks!
|
I'm currently reading this classic paper "How To Simulate It" and on most of the definitions it is using the term probability ensemble to represent the message space. From my understanding a probability ensemble is like a stochastic process and a probability distribution is an instance of a stochastic process. For exam... |
When reading about the comparison of interactive and non-interactive Zero-Knowledge-Proofs, I came across the statement that non-interactive Zero-Knowledge-Proofs are not deniable compared to interactive ones.
What makes an interactive Zero-Knowledge-Proof deniable, and how is that property lost when transforming it in... |
When verifying a (HMAC) authentication tag it is often indicated that a constant-time comparison is required for security. I can see how leaking information about a password hash can introduce a mild vulnerability as the password hash may become known. However, we're talking here about a calculation over a known and ra... |
Most real-world RSA implementations add padding and such that break the multiplicative homomorphism of raw RSA. However, this multiplicative homomorphism can be useful.
I haven't seen any existing schemes that make RSA semantically secure but maintain the multiplicative homomorphism properly. The only scheme that I h... |
I am developing an implementation of OpenPGP, and I'm using Kleopatra to test my generated messages.
After generating a signature for a message, I compress both the message and signature, but upon decrypting it in Kleopatra, it's treated as an unsigned document, returning to me decrypted and decompressed message with t... |
I was recently trying to gain a better understanding of the SHA-512/256 algorithm and on this NIST example they use the word "abc" as the input. In the Block Contents, it shows the expected hexadecimal 616263 (abc), although why is it directly followed by 0x80 and 0x18 at the very end?
Block Contents:
W[ 0] = 616263800... |
Suppose there is a popular system that is widely used by a huge amount of people. Its security protocol provides a finite group with a generator $g$, and users need to choose a random number $r$ and calculate $h=g^r$ in a certain phase. This is commonly seen in many schemes.
Since this system is widely used by many peo... |
For use use in Encrypt then MAC scheme i am considering using HMAC-SHA256 with 256 bit key, i am wondering if i should use HMAC-SHA512 to be post quantum secure, will simply using HMAC with 256 bit key alone irrespective of hash function will be post quantum secure?
|
Assume to neglect:
The man in the middle attack.
The efficiency of symmetric encryption over asymmetric
I can't understand the usefulness of TLS, with respect to the security, if both parties exchange encrypted and signed messages (i.e <ciphertext, signature>) without TLS.
Is the security communication using TLS the... |
AES uses 256 bit keys. Newer symmetric ciphers like Salsa20 still use at most 256 bit keys. But everyone talks about the security level after quantum computers so they say 128 bit key will provide 64 bit key, 256 bit will be 128 bit. So in the post quantum world we'll have no longer 256 bit security, right? So why don'... |
Public nonces can be problematic for privacy when they can be considered metadata. They can also be troublesome for security if you do things like using a hash of the message as the nonce.
PASETO now derives the nonce alongside the key using HKDF on the input keying material with a 256-bit salt. Thus, the actual nonce ... |
I have two PRGs:
$$G: \{0,1\}^l \rightarrow \{0,1\}^{3l}$$
$$G': \{0,1\}^m \rightarrow \{0,1\}^n , n \gg m$$
I also have a PRF:
$$F: \{0,1\}^{3l} \times\{0,1\}^m\rightarrow \{0,1\}^m $$
Is:
$$\operatorname{F}'(k, x) = G'(F (G(k), x))$$
a PRF?
How can I actually prove this? I was trying defining two different hybrid... |
Background of the question:
I’m working on constructing a cryptosystem to achieve a specific goal that could utilize partially homomorphic schemes. (details of the cryptosystem are out of the scope of this post)
Are there any production-grade usages of any partially homomorphic scheme (ElGamal, Paillier, etc) that mig... |
Background:
I've seen that the value of plain text should be lesser than p*q as per this slide.
I was reading Tanenbaum's Computer Network book the next night, and I saw this thing that I'm not sure that I understood!
I feel he's telling that a PlainText should be less than $$p*q$$.
I'm not getting $$2^k < n$$ thing.
... |
I'm currently building an implementation of the dynamo paper, yottastore. Imagine it as a huge, distributed, hash map.
To find the node holding a key, I use rendezvous hashing (an improvement over consistent hashing), which requires 4 hashes. In order to avoid hash flooding attacks I'm using a keyed hash function, usin... |
As I understand, the one-time pad can be generalized to any finite group. So, for example, if you consider $\mathcal{P} := \mathcal{C} := \mathcal{K} := \{0, 1, ..., 2^{n}-1\}$ for an integer n, and you draw one-time keys $k$ uniformly from $\mathcal{K}$, then encrypting a plaintext $p$ by modular addition $c = p + k\;... |
I'm looking for a way for a single individual to sign or otherwise provide proof of ownership of two private keys from keypairs $A$ & $B$.
Simultaneous ownership is important. Alice can't do part of the proof with $A$, then pass the proof to Bob to finish with $B$. The proof requires both keys in a single step. E.g. Si... |
I have been considering an approach to incentivize cryptocurrency miners to verify claims of quantum computational supremacy. Briefly, miners find collisions $f(x_1)=f(x_2)=y$ of some known $f:m+1\mapsto m$-bit hash function $f$. I envision that a quantum computer broadcasts and commits to $y$ and to another sting $d... |
For a project I'm working on, I need to perform addition, subtraction and dot operations on relatively large encrypted 2x2 dimensional matrices.
The project is written in python and I am using the numpy library for matrix operations.
In order to be able to encrypt the data and perform mathematical operations, I receive... |
I was asking myself the following question but I'm not really sure if it's in this way:
I have a first $PRG$:
$$G_1: \{0,1\}^{\lambda} \rightarrow \{0,1\}^{\lambda+1}$$
Now I want to construct a second $PRG$ that is structured as follows:
$$G: \{0,1\}^{\lambda} \rightarrow \{0,1\}^{2\lambda}$$
Such that ($||$ is the co... |
Contemplating using YubiKey’s challenge-response feature to hash public passphrases.
By public, I mean an attacker could potentially exfiltrate passphrases but, not having YubiKey*, passphrases would be useless.
Is such as scheme secure in 2022 and is it quantum-computing safe?
Thanks for helping out!
*HMAC is computed... |
Given an integer $b$ modulo a prime $q$, one can define a `rounding’ function $\lfloor b\rceil_p$ for a prime $p$, $p<q$, as follows: $$\lfloor b\rceil_p = \lfloor \frac{p}{q}\cdot b\rceil\bmod p.$$ In the paper Pseudorandom Functions and Lattices, it is claimed that the statistical distance between the uniform distrib... |
I have been trying to solve the following:
Given a scheme that is perfectly correct but not perfect secrecy. It satisfies computational security, however, in that, if Q = Pr[Adv wins no query semantic security game], then
$$Pr[Q] \leq \frac{1}{2} + \epsilon$$
for some negligible $\epsilon$ in $n$ which is the security ... |
I have a question about symmetric message authentication codes (MACs).
Say Bob sends encrypted messages to Alice using a symmetric cipher. As I understand it:
(1) Their threat model could or should include the risk of an active attacker sending Alice maliciously crafted ciphertexts for the purpose of exploiting bugs in... |
I'm reading an article "A Tweakable Enciphering Mode" by Halevi and Rogavay and wondering about one statement. On page 6 there are 3 inequalities:
$$
\begin{equation}
\begin{split}
\mathbf{Adv}_{\mathbb{CMC}[\text{Perm}(n)]}^{\pm\text{prp}}(n\sigma) & \leq
\frac{5 \sigma ^ 2}{2 ^ n} \\
\mathbf{Adv}_{\te... |
Given some intervals of long integers (64 Bits). I need to generate alphanumeric strings which:
should be used like passwords(known only by few individuals)
must always be the same for the same integer
must always be different for different integers
must not be easily to be created for another integer if they are know... |
I just came across this question, but it does not really answer my main concern that I have regarding password tokens.
To authenticate a client who is not logged in; I generate two random tokens and then use one as the DB selector, the other one as the validator, to authenticate an unknown client for a given operation,... |
I have the public key, the string itself (not a file), and I am trying to figure out the SHA256 fingerprint, as in the image attached. The default key generated by PuttyGen is SSH-2 RSA with a SHA256 fingerprint. This would help me identify the keys by their fingerprints in the AWS S3 containers, given that I stored on... |
Not sure about the security implications of making HMAC SHA1 message and corresponding hash public (secret would remain… secret)?
Evaluating if that would help an attacker crack algorithm.
|
I have been playing with AES256-GCM in NodeJS crypto library and it shows that the original message can be decrypted without caring about the auth tag.
So can a non-tag verified decryption be secure? Only send the ciphertext+iv to the attaker and assuming he/she knows the ecryption method(in an open source github)?
Upd... |
I wanna create from several inputs/sources should be formed into one hash value for controlling of different thinks later.
Example:
String + File
String + String
File + File
String + File + String
From the logic now there a different ways to do that:
CREATE HASH [(HASH(String)) + (HASH(File))] = HASH-RESULT
CREATE H... |
I am still studying for my crypto 101 and I have a problem with one exercise that I can't find where I'm wrong...
We have p=11 and q=19 (so n=p*q=209) and e=17. I need to encrypt m=5 with RSA system.
So: Crypt_Msg = me mod n = 517 mod 209 = 80
Ok... now I want to decrypt that value (Crypt_Msg=80)...
First of all d = in... |
I am tasked with creating a practical demonstration of a random number.
This means, generating a random number, then showing something practical with it.
Does anyone happen to know something practical to do with it, or use it in a software, or a communication demonstration?
|
This question was originally asked on Reverse Engineering SE, but I
felt that the main part of my question doesn't relate to RE directly,
and it's more about a fundamental understanding of cryptography, hence
why the original question has been removed and re-asked here.
I'm trying to analyze the UDP packets of a P2P ... |
I thought I understood cofactor clearing before I read this write-up which generally seems quite popular (lot of other sites link to it) - Cofactor Explained: Clearing Elliptic Curves' dirty little secret
Let's say you have a group of non-prime order like say $44$. Now, $44 = 11 * 4$. We are interested in working in th... |
I looked into this paper on privacy-preserving aggregation by Marc Joye and Benoit Libert (https://www.ifca.ai/fc13/proc/3-3.pdf). A key element in their scheme is a hash function defined as $$H: \mathbb{Z} \mapsto (\mathbb{Z}/N^{2}\mathbb{Z})^{*}$$ without giving an example of such a construction, which left me puzzle... |
The paper Efficient Schemes for Committing Authenticated Encryption introduces a framework for committing security notions that includes:
CMT-1: commit to the key.
CMT-3: commit to the key, nonce, and associated data.
CMT-4: commit to all inputs, so the message as well.
Then there are D-notions referring to decryptio... |
For some time now, we have been assessing the risks from a GDPR perspective when data (data-at-rest) in the Google Cloud is fully encrypted using native means. This means that we create both the KEK and the DEK completely with Google Cloud KMS and encrypt the storage buckets with it.
Also, we are not currently subject ... |
I was just watching this video on the Double ratcheting protocol.
at around 31:37, the presenter says that the protocol only provides weak forward secrecy.
I've only ever heard about a distinction between Perfect forward secrecy, and "normal" forward secrecy. Where the perfect version is resistant to leakage of long te... |
In some contexts (ZKP of the validity of a decryption key without revealing the message in public, section 3.3 of CAO21), one wants to emit a proof that the encryption of a message with a public key cryptosystem $Enc(m)$ satisfies some properties. Examples of such properties are "$m$ is a private key associated with a ... |
Is it possible that there is a cryptographic hash function that outputs a c-membered subset of the n-membered set?
In other words, can the set of the binary representation of c-membered subsets of the n-membered set, be the range of a hash function?
The hash function will look like below (for 2-membered subset of the 4... |
I have got 4 variables $n$, $x$, $y$, and $z$:
Here, $n = p\cdot q$ with $p$ and $q$ are distinct primes
\begin{align}
x &= m^p \bmod n\\
y &= m^q \bmod n\\
z &= m^n \bmod n\\
\end{align}
How can I find $m$?
|
Is there a special limit in the range of the hash function?
More specifically, is it possible that there is a cryptographic hash function that outputs c-membered subsets of the n-membered set?
In other words, can the set of the binary representation of "all" c-membered subsets of the n-membered set, be the range of a h... |
My question is whether it is possible to use "another" algorithm than the sha256 to hash data but end up with the identical sha256 hash (obviously without using the sha256 algorithm)?
|
I'm implementing a content-addressable file store - similar to a key/value store, but the key is always a hash of the value.
I'd like to build an encryption layer for it, to hide what data is being stored on the server device. Encrypting the data is easy and doesn't need anything special - it'd be just like encrypting ... |
I'm trying to understand Merkle–Damgård construction. We can hash as many blocks of data as we want, if I understand it right. But then it looks like when input is bigger, then also time to compute hash is longer, isn't it?
So is it true that SHA-256 would also calculate the hash longer if input is bigger? Therefore ar... |
Let E be some IND-CPA public key encryption scheme. Given two users with public keys $pk_0,pk_1$ respectively, each user $i$ selects a nonce $r_i$ at random and computes an encryption $c_i = E_{pk_i,r_i}(b_i)$ of some secret bit $b_i\in\{0,1\}$ selected by the user. Is it possible to construct an algorithm A such that
... |
In my open source with offline client side encryption application, I plan to use AES-CTR or ChaCha20 without MAC instead of GCM or Poly1305 since:
There is no database, the ciphertext, nonce, tag stored and encryption happened completely on the user's device, no need to verify authenticity or integrity with any API en... |
Are there any deterministic commitment schemes? What are their security properties, if so? Most ones I see are randomized.
|
I want to understand the difference between randomized encodings and indistinguishability obfuscation (iO).
Are randomized encodings a special type of iO?
|
A symmetric key schedule is a key schedule of the form $(k_1,\dots,k_{n-1},k_n,k_{n-1},\dots,k_1)$ or of the form $(k_1,\dots,k_{n-1},k_n,k_n,k_{n-1},\dots,k_1)$. A skew symmetric key schedule is a key schedule of the form $(k_1,\dots,k_{n-1},k_n,g(k_{n-1}),\dots,g(k_1))$ or of the form $(k_1,\dots,k_{n-1},k_n,g(k_n),g... |
In Boneh et. al.'s ABE scheme (https://eprint.iacr.org/2013/669.pdf, https://link.springer.com/content/pdf/10.1007/978-3-642-55220-5_30.pdf), the result value for the arithmetic function is selected and fixed to zero. In other words, if the arithmetic function is defined as $f(\mathbf{x})$, the user can decrypt if and ... |
Nested attributes were introduced for the first time in the paper with the title "SmartABAC: Enabling Constrained IoT Devices to Make Complex Policy-Based Access Control Decisions".
What is the difference between nested attributes, multiple attributes, and hierarchy attributes?
In this paper, the authors make 6 policy ... |
I can’t figure out why the static public key of the initiator/recipient cannot be sent as plain text in the Noise KK pattern and what kind of cryptographic vulnerability does it provide?
For example, in the pattern Noise XX, the recipient's static public key is sent encrypted, although it can be easily obtained by man-... |
If a user cannot generate a proof locally for a large circuit in SNARK in his phone or browser, he can delegate it to a server. However, he has to tell the witness to the server(s), which violates the zero-knowledge property of SNARK. What is the state of the art for delegating proof generation without disclosing the w... |
Would it be over-engineering to for example hash the random numbers a random amount of times too, for instance when using the CSPRNG in client-side JavaScript? (assuming this is not the strongest CSPRNG)
Edit: Or would it instead be wise/necessary to rely on more devices of randomness (like mixing/hashing a Client Secu... |
In a sigma protocol, a well known transformation to a signature is Fiat-Shamir, where message derived randomness is mixed into the randomness of the challenge. A natural example is Schnorr signatures. This is also called a Signature of Knowledge.
Suppose you start with a modern, transparent ZK-SNARK to prove knowledge ... |
How is the seed of PRNGs generated? They can't be hardcoded I am guessing.
|
In this paper Alzette "ARX-box" is presented and on page 9 authors claim about XORing round constants:
They also break additive patterns that could arise on the left branch due to the chain of modular addition it would have without said constant additions.
Round constant is "c":
x ← x + (y ≫ 31)
y ← y ⊕ (x ≫ 24)
x ← ... |
I know this is theoretically bad practice, but please bear with me…
Assuming following spec:
Salt and IV are randomly generated using cryptographically-secure RNG.
Argon2 is used as KDF so key_1=Argon2(shared_salt, passphrase_1) and key_2=Argon2(shared_salt, passphrase_2).
Both passphrases are not vulnerable to dict... |
In RFC 7748, it is explained how the Montgomery curve, curve448, is deterministically generated from the prime $p = 2^{448} - 2^{224} - 1$. It is also explained how the generator (given below) for curve448 is derived.
U(P) 5
V(P) 355293926785568175264127502063783334808976399387714271831880898
4351... |
Suppose I have a webpage that publishes some number x that changes over time and the page is publicly accessible.
I would like to somehow create a proof that this webpage published value y at time t. Is there a way to make this possible?
This needs to be done without any sort of central authority, so it's not good enou... |
For non-deterministic ECDSA:
Given message $m$ and private key $p$, produce a series of signatures $s_i = signature(p,m)$, $i=[1,n]$.
Does there exist some function $f$ such that $j_i=f(s_i)$ and $j_1=j_2=...=j_n$ ?
|
I am trying to find $d$ given $e$ and $\varphi(n)$. I found a solution online but I don't really understand why it works.
sage: bezout = xgcd(e, phi); bezout
(1, 4460824882019967172592779313, -1667095708515377925087033035)
sage: d = Integer(mod(bezout[1], phi)) ; d
4460824882019967172592779313
sage: mod(d * e, phi)
... |
For semi honest MPC protocols, adding some errors can easily make the output wrong.
I wonder beyond that, can malicious adversaries make some attacks against semi-honest protocols to obtain private inputs or some other private data? And if they can, how to do that?
I wish to get some answers or literature about this qu... |
Consider a family of pseudorandom functions $F$, each member $f_k$ of this family is indexed by a key $k$. It is true, due to a result by Barak et al, that black box obfuscation is not possible for a generic family of this type.
However, is it possible to apply something like indistinguishability obfuscation ($\mathsf{... |
I've encountered the following question while practising for an upcoming exam in Cryptography and would like to know if I'm on the right track:
The following is a suggestion for a DES-based commitment scheme:
To commit to $0$, choose a random $k$ and return
$DES_k\big(\overline{0}\big)$ where $\overline{0}$ is a 64-bi... |
Are there any clever (fast) methods for adding the basepoint (generator) to an arbitrary point on elliptic curve, finally ending in affine coordinates?
I.e. if G is the generator for a group on the curve (e.g. 25519) and P is an arbitrary point, is there a faster-than-naive way to find P + G in affine coordinates?
I'm ... |
I am trying to implement a random number generator (which should be cryptographically secure), I am thinking of combining multiple LFSRs, is it a good choice?
I've also heard I can create RNGs from hashing algos like shake256, How is that done?
|
EDIT: At a high level I am trying to create a scheme where Alice can prove to Bob that some external site has a certain piece of data (say her Bank account has balance > X) . She does not want to give Bob access to her account, but wants to prove that her bank website returns a certain result without showing it... basi... |
Every API that I have ever signed up with gives you a secret key that you can then paste into your application. They know the key, and so do you. (The one exception may be VAPID for Web Push).
Why is this the case? Some apps and protocols already give users a public/private key pair, and store only the public keys in t... |
I need to use Azure Key Vault HSM to sign arbitrary data in a PKCS#7 CMS. There are plenty of libraries and packages that can do this if you supply them with the private key, but obviously I don't want to export the private key from the HSM, so I've built my own PKCS#7 object in C# using Asnwriter.
I'm using the ITU-T ... |
I have an application that erasure codes data in chunks. Lets say there are 3 data chunks and 2 parity chunks (it could also be 6-3, 10-4 etc). Each chunk is 1MB of data and has a CRC32 checksum associated with it.
D1-CRC1 D2-CRC2 D3-CRC3 P1-CRC4 P2-CRC5
To recover lost data, I need any 3 of the above chunks to recove... |
Is there any software that can output all possible solutions to a substitution cipher?
I have a 34 character substitution cipher as follows:
ABHIJCKDELMFNOEPQ
RDSTUVWGFADBXCYGZ
15 of the characters in the cipher are repeated.
I would like a software to output all possible word combinations that will fit the cipher (Eng... |
A hybrid scheme is a combination of a classical and a post-quantum scheme. In the hybrid model, if even the post-quantum section is broken, the hybrid scheme is still secure against non-quantum attacks. But, as far as we know, NSA doesn't like hybrid schemes, for example NSA didn't consider hybrids in her new updated C... |
I am looking for some algorithm or implementation on Pailler cryptosystem-based verifiable shuffles for mixNet. So far, all the verifiable shuffles and mixNet are available for ElGamal cryptosystems like the Groth method, etc. Does anyone know the implementation done specifically for Paillier encryption? If not, can I ... |
I am building a chat application where I want to encrypt each character while they are typing. I would require a stream cipher for that.
I am planning to use AES-CBC mode with HMAC. Are there any security risks if I use AES-CBC mode to encrypt `0's to generate blocks of the one-time pad and then use that one-time pad s... |
Suppose we have a 32-bit message $ M=(m_1,..m_{32}) \in \{0, 1\}^{32} $ and we have secrets $ F_{i, b} $ and $ G_{i, b} $ (2x32+2x32=128 secrets in total).
$$ \forall 1 \leq i \leq 32, b \in \{0, 1\} : F_{i, b}, G_{i, b} \in Z_q $$
And now we define two functions $ f $ and $ g $ respectively:
$$ f(m_1, .., m_{32})= \su... |
I'm trying to come up with a Zero-Knowledge proof for the following setup.
Using RSA encryption, Peggy chooses a random $M \in \mathbb{Z}^*_n$, computes
$C=M^e \mod n$ and sends $C$ to Victor. Peggy wants to prove that she
knows $M$.
I've constructed the following protocol, but am unable to justify soundness - which ... |
Good day.
How I can modify elliptic curve point, like number modulo ?
number example, with unknown privkey 5555555555 :
5555555555 % 2500 = 555
how to get pubkey with privkey 555, from pubkey with privkey 5555555555 using any math operation or code incude change modulo of curve, calculatex and y coordinates modulo 555... |
Ed25519 uses a composite order Elliptic Curve but works in the prime order subgroup of the main group. As per group theory, the subgroups use the group operation.
However, as per this, Ed25519 implementations don't do this.
But every existing implementation implements scalar arithmetic $\bmod q$, the order of the prim... |
I am designing my first web3 app and I would like to use MetaMask as an identity and crypto provider. My web3 app will encrypt user data with AES-GCM, but I do not want to generate and store an encryption key (as well as iv/salt) anywhere on user device. Instead, I would like to use MetaMask connection and the private ... |
Below is a suggestion for a zero knowledge proof for the existence of both a $k$-independent set (IS) AND a $k$-vertex cover (VC). It was given as an example of an interactive proof that is not computational zero-knowledge due to leakage of information, and I'm having trouble understanding why.
Peggy selects a random ... |
Imagine you have RSA key pair. You also have some text data. So public key and text data are visible to everyone. Question is, if you sign the text_data with the private key, is the result considered as good secret? For example is it good idea to convert it to base64 string and use it as a password?
Real world problem ... |
Some applications may require quick transition to post-quantum signatures, and stateful hash-based signatures fill that role (cf. CNSA 2.0).
My question is (ignoring statefullness, focusing on space/time efficiency), how do these schemes (e.g. LMS/XMSS) compare to whatever is used now (RSA, DSA, ECDSA)?
|
I've seen some mentions of a "SHA-256/192" online. Clearly, this means the output of SHA-256 is truncated to 192 bits, but does it also use different Initial Values like SHA-512/256?
|
Ed25519 uses a composite order Elliptic Curve but works in the prime order subgroup of the main group. The signing operation should be using a generator/Base Point from the prime order subgroup.
This blog seems to say the following - Honest Ed25519 signers only work in the prime-order subgroup (i.e they chose a generat... |
Ed25519 uses a composite order Elliptic Curve (with a cofactor $8$) The algorithm however in the prime order subgroup of the main group. The signing operation should be using a generator/Base Point from the prime order subgroup.
There are the parameters
Order of the curve is $8.q$ where $q$ is a large prime.
$a$ = scal... |
is the complete NTT is the fastest algorithm to multiply polynomials or there are hybrid versions that are faster than complete NTT multiplication?
|
RFC 5869 Defines HKDF-Extract in section 2.2 as:
HKDF-Extract(salt, IKM) -> PRK
TLS 1.3 RFC 8446 defines the first part of the Key Schedule like this:
0
|
v
PSK -> HKDF-Extract = Early Secret
|
... <<< omitting unrelated lines >>> ...
v
Derive-Secret(.... |
To prevent second pre-image attacks, the Merkle Tree implementations I've looked
at add a 0 prefix to the leaves and a 1 prefix to all other nodes as described
at the bottom of this link:
https://flawed.net.nz/2018/02/21/attacking-merkle-trees-with-a-second-preimage-attack/
If we assume the Merkle Tree is a Complete Bi... |
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