Cryptography Stack Exchange
Cryptography Stack Exchange

Most Popular

more tags
1500 questions
15
votes
2 answers

Argon2 - memory setting - lower bound?

(I realize this is yet another Argon2 "how do I configure" question, but the existing questions I've found don't really help. If I've missed one, happy to have this closed). Deploying Argon2 (with the Argon2id variant) into a server environment to…
Callie J
  • 253
  • 2
  • 7
15
votes
1 answer

Calculate all possible keys for AES 128 encryption to exploit hardware encryption

Some background: I am using the MicroChip ATAES132a for hardware encryption/decryption. The ATAES132a is very configurable and can be misconfigured in such a way that the encryption/decryption will be performed using the same nonce. In theory, if…
PhillyNJ
  • 264
  • 5
  • 13
15
votes
3 answers

What are the differences between proofs based on simulation and proofs based on games?

what are the main pros and cons of proving the "security" of a crypto scheme under simulation proofs instead of game based proofs?
curious
  • 6,160
  • 6
  • 32
  • 45
15
votes
3 answers

Is it possible for a cryptographic algorithm to limit the number of times a package/ciphertext can be decrypted?

I got the idea from Eve Online's BPCs (Blueprint Copy). The in-game explanation is that the license to manufacture a copy of a starship is limited to X times, and afterwards the BPC is automatically corrupted. I understand that the resulting…
Erik Gaius Capistrano
  • 169
  • 1
  • 4
15
votes
2 answers

Why is pqRSA in the NIST PQC submissions?

In the NIST post-quantum cryptography workshop, the round one submissions included pqRSA. If memory serves, this is an implementation of RSA using the product of a very large number of 4096-bit primes to protect against Shor's algorithm. It requires…
forest
  • 15,253
  • 2
  • 48
  • 103
15
votes
1 answer

Are hash functions strong against quantum cryptanalysis and/or independent enough of mathematics?

I work on ethereum and other blockchain technologies. And seeing that quantum pc's are someday going to see the light I have some questions / doubts. I was wondering if hash functions are strong enough to hold up against quantum computers (that in…
CPereez19
  • 325
  • 1
  • 2
  • 7
15
votes
1 answer

ECDSA Signature R|S to ASN1 DER Encoding question

I am trying to test my understanding on ECDSA Signature r|s to ASN.1 DER Encoding for NIST P-256. I have r|s and when I convert this into ASN.1 DER in Java. I get following format: 0x30|b1|0x02|b2|r|0x02|b3|s b1 = Length of remaining data b2 =…
vison
  • 163
  • 1
  • 1
  • 5
15
votes
3 answers

What is the main difference between finite fields and rings?

In the course I'm studying, if I've understood it right, the main difference between the two is supposed to be that finite fields have division (inverse multiplication) while rings don't. But as I remember, rings also had inverse multiplication, so…
Jobo
  • 161
  • 1
  • 5
15
votes
2 answers

Does a trace of SSL packets provide a proof of data authenticity?

I'm wondering if it would make sense to record a whole HTTPS session, publish its encryption keys and present it to third parties as a proof that this particular data was sent by a given server identifying itself with some signed certificate. Could…
d33tah
  • 363
  • 1
  • 14
15
votes
1 answer

How to to calculate the hash of an unordered set

Suppose I have a set of elements, with known hash (e.g. SHA-2). How can I calculate the hash of the set? With it I mean an unordered set, so the order of elements is undefined and shall not play any role in determining the hash of the set. In theory…
ragazzojp
  • 413
  • 4
  • 8
15
votes
2 answers

When adding two points on an elliptic curve, why flip over the x-axis?

Every introduction to elliptic curves that I've read hasn't explained this. If you have two points P and Q on an elliptic curve, to find P+Q, you draw a straight line through the points, find the third point of intersection with the elliptic curve.…
Kevin
  • 161
  • 1
  • 6
15
votes
2 answers

Is it possible to recover the seed used by Python's pseudo-random number generator?

I generated some random numbers using a Python script. I have the first 40 numbers of the sequence. Is there a way to recover the seed or find the next 460 numbers in the sequence? The numbers were generated using the following code. import…
SeeCSea
  • 161
  • 1
  • 1
  • 5
15
votes
1 answer

Doubt about published test vectors for gimli hash

In https://eprint.iacr.org/2017/630.pdf and https://gimli.cr.yp.to/gimli-20170627.pdf there are test vectors for the gimli hash function. I have compile the reference C code test_hash.c from https://gimli.cr.yp.to/gimli-20170627.tar.gz on two…
gammatester
  • 1,005
  • 1
  • 8
  • 12
15
votes
2 answers

Mixing algorithms for password hashing good or bad?

So I've come across the following algorithm for hashing passwords function hashpassword($str, $salt) { $hashed_password = md5($str); $hash = md5('more_salt'); $hash = sha1($hash.$salt); $hashed_password =…
Luke
  • 153
  • 1
  • 4
15
votes
3 answers

Why do Feistel ciphers need round keys?

Looking at the design for Feistel ciphers, they use a list of round keys which are generated from the main key using the key schedule of the associated block cipher. Some block ciphers need this as to prevent repetition, but why does a Feistel…
Daffy
  • 2,389
  • 17
  • 29
1 2 3
…
99 100