# All Questions

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### McCallum-Relyea exchange on x25519 elliptic curve

Background I have a degree in electronics engineering, I'm not bad at programming with many languages, but I'm not that good at cryptography, I'm just able to use that from libraries, and I understand ...
1 vote
23 views

### Publishing a message with a computationally enforced delay [duplicate]

I'm looking for a way to publish a message, so that it will only be publicly known after some time (let's say a few minutes). Even I shouldn't have the power to prove what my message was, before this ...
72 views
+50

### In a PGP like Application , would compress and encrypt leak information

would compress and encrypt on data comromise security for PGP like application, would it be secure for use in Encrypted Messaging? I have heard its safe for data at rest encryption , i have heard ...
437 views

### What is this EC key derivation method called?

I'm looking to identify the EC key derivation method used in Hyperledger Fabric. I can't find anything in the docs or the protocol specs, but the functions' code is here for the private key and the ...
50 views

### For password-based authenticated encryption is it OK to derive the auth key from the crypt key with 1 iteration?

That is, in the case where the iterations value is a large number, since iterations are costly is there a difference in security of doing something like this, where two separate derivations are ...
1 vote
23 views

### Breaking Ed25519 Discrete Logarithm with Degenerate Curve Attack

Following this question ed25519 attacks and also this paper on degenerate curve attacks https://eprint.iacr.org/2015/1233.pdf, I tried to implement my own attack: Given a point (0, y) and a scalar (k),...
4k views

### Quantum Computing Used to Break RSA by "fixing" Schnorr's Recent Factorization Claim?

There is a claim by Chinese researchers making the rounds (Schneier's blog here) that RSA can be broken by Quantum Computers. The paper is on arXiv. Wading through the discussion in Schneier's blog, ...
365 views

### Security Strength of Symmetric vs Asymmetric Ciphers

NIST SP 800-57 Part 1 rev 5 section 5.6.1.1 gives following comparison between different encryption types. For example, it shows that 3TDEA, RSA-2048, ECC224 provides security strength of 112 bits. ...
1 vote
21 views

### Should I implement a key store / key management system into my python library? [closed]

I've created a python library that uses both RSA and AES encryption to allow for hybrid encryption of text or images. I am wondering if I should implement a keystore and/or a better key management ...
1 vote
31 views

### Expanding standard simulation-based proofs to UC proofs

This is a follow-up question to Mikero’s answer to Simulation-based proofs and universal composability proofs. Let there be some protocol $\pi$ running between two parties $A$ and $B$. Furthermore, ...
143 views

### How will the ability to do comparison or modulo efficiently in Finite Cyclic Groups break Elliptic Curve Cryptography?

This is from Vitalik Buterin's post. Here he says Note that modulo (%) and comparison operators (<, >, ≤, ≥) are NOT supported, as there is no efficient way to do modulo or comparison directly ...
1 vote
135 views

### Why doesn't TLS provide E2EE?

Why doesn't TLS provide end-to-end encryption? This question is somewhat related to this, this and this. If you want to talk to someone, say, through facebook, the TLS connection ends in the ...
1 vote
159 views

### One-way function with combination sets as output / image

One-way functions generally operate on bit strings, for the input and the output. Are there any examples of one-way functions that produce a combination set in output? Let's call this function $f$. ...
1 vote
319 views

### PAN authenticatable irreversible tokenization algorithm

I need to implement algorithm to create authenticatable irreversible tokens from PAN, without using any secrets. Is it possible? Is there any standards for that from associations? I was thinking ...
1 vote
56 views

### Will a bloom filter produce false negatives if it becomes full?

Does the "no false negative" property hold if a bloom filter becomes full? I tried playing with this interactive example but it only gives the false positive probability.
377 views

### DDH hardness with shared public parameters

DDH is believed hard for subgroup of $ℤ^*_p$ with order $q=(p-1)/2$ when $p$ is a safe prime chosen randomly. What if $p$ isn't random: When parameters are shared, $p$ mightn't have been chosen ...
1 vote
13 views

### Arithmetic Circuits to R1CS. Do we consider addition gates or not?

Here is Ariel Gabizon's Blog for the process of converting Arithmetic Circuits into R1CS - https://electriccoin.co/blog/snark-explain5/ Here, he writes We assume multiplication gates have exactly two ...
2k views

### How does TLS differ from SSH from a strictly cryptographic perspective?

How does TLS differ from SSH from a strictly cryptographic perspective? I know that there are many non-cryptographic differences between them, but I would like to know the cryptographic ones.
1 vote
134 views

### Key generation for DH key exchange - benefits of using KMI

Context We need to generate a key pair in order to perform DH key exchange with the other party. Some suggest to use a KMI solution (think: AWS KMS or like) in order to generate the key pair. ...
23k views

### How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?

If cryptanalysts today were to crack the original Enigma machine, “how fast” or “how easily” could they do it? What methods would they use? The original cracking was significantly helped by operator ...
1 vote
66 views

### What would be an ideal use case for FPGAs in cryptography?

So, for my capstone project, I've been working on a cryptographic algorithm accelerator on an FPGA. While it did get approved, I've been suggested to work on a more application-based idea that could ...
1 vote
117 views

### OWF from PRG and OWF

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 ...
60 views

### Which ciphers have been defined that use the Keccak sponge?

There seem to have been defined multiple ciphers using the Keccak sponge as building block / primitive. These seem to have escaped public attention, possibly because they have not been standardized ...
1 vote
392 views

### Bitwise operations in FHE

Im reading about FHE and the libraries implementing it (SEAL, HELib). I saw that SEAL doesn't support bitwise operations but I wondered if its theoretically feasible. For example, bitwise-ing XOR an ...
1 vote
114 views

### RTL solutions to Post quantum candidates

I am looking for RTL implementations of the PQC finalists for KEM (McEliece, Kyber, Saber and NTRU) Saber provides the following repository McEliece provides some code from their website, but as far ...
1 vote
72 views

### ECDH between identical public keys

We are using libsodium and regarding exchanging secrets we would like to use the so-called crypto_box (https://libsodium.gitbook.io/doc/public-key_cryptography/authenticated_encryption). Under the ...
15 views

### How to modify a OTP physical token for secure comms [closed]

I would like to build a bank physical token similar to the RSA SecurID that doesn't require the internet. Nowadays banks are moving to digital OTPs such as Google Authenticator or SMS OTPs for ...
103 views

### A modern rotor machine, could it be any safe?

I wonder if a rotor machine similar to enigma can be considered secure by today's standards under four conditions: A rotor machine which consists of 50 rotors picked out of a set of 100. A rotor ...
22 views

### Can salt and XOF be used to create a symmetric cipher? [duplicate]

I'm new to crypto, and I've got an idea and I want to get some feedback if it's even a right direction. Let's say that I create a symmetric cipher by using an XOF with a salt and a secret key. ...
1 vote
48 views

### How do certificates add data to public key and how is this implemented into TLS?

I want to create a self signed PKI for a couple servers I am running. I am finding tutorials with copy paste commands from openssl, and hand waving explanations that describe the general purpose of ...
84 views

### Does having multiple salted hashes lower pre-image resistance?

A common method to mitigate the effect of rainbow tables is to add a string to the end of the user password before hashing, a process known as salting. However, let’s say for example that someone uses ...
66 views

### About the public key in Digital Signature

Please I do have a question as you know to sign a message the sender must first of all calculate the hash of the message and then encrypte it using his private key and then send it to the reciver and ...
1 vote
65 views

### Entropy for TLS 1.2: how much is needed for linux servers?

I am trying to fix issues with a server where the server keeps freezing up and needs to be restarted. I recently started hearing about entropy and it importance to secure tls keys in linux. The one ...
171 views

312 views

### Error-Correction capabilities of encryption?

This is motivated by this question about the recovery of (corrupted) encrypted files, and in particular the statement (in the answer): But If I know the algorithm and the key and I make a custom ...
69 views

### Any simple, cryptographically secure AES-based DRNG?

I am looking for a DRNG/DRBG (cryptographically secure) algorithm/function (which I can program into js). I am looking to use a DRNG as a seed generator for generating multiple, identical AES keys on ...
37 views

### Commitments and snarks: overflow over a finite field

Let x = 100 - initial balance M = 1,000,000,000 transfer amount final balance M+x E(p-M) + E(M + x) = E(p - M + M + x) = E(p + x) = E(x) producing correct proof of the fact that the final balance ...
23 views

### Is there a way to timestamp data physically without using any digital means like a trusted timestamp authority? [closed]

Is it possible to prove that a certain data existed before a certain time without relying on digital technology? I mean you would have an object that contains a message and the date when the message ...
27 views

### How to do the encryption and decryption when key is not known in One Time Pad? [closed]

The one-time pad encryption of plaintext mario (when converted from ascii to binary in the standard way) under key k is: $$1000010000000111010101000001110000011101$$ What is the one-time pad ...
20 views

### Is there any blockchain where tokens can only be earned via work but not sent to other addresses? [closed]

I was wondering if a blockchain could reward nodes that contribute work with tokens that can be spent on that blockchain to receive work done, but the tokens cannot be sent. They are bound to the node ...
1k views

### Overview of relations between cryptographic primitives?

Is there a web page that gives a graphical (or, alternatively, a textual) overview of known implications and separations between cryptographic primitives? More specifically, I am looking for something ...