16 votes

Can I change the radio frequency according to my encryption algorithm?

More physical layer security than encryption. Spread spectrum wideband radio using frequency hopping does this. https://en.m.wikipedia.org/wiki/Frequency-hopping_spread_spectrum What is required is a ...
kodlu's user avatar
  • 22.1k
14 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

Some facts for you to consider: Brutal-force a cryptographic key is much harder than brutal-force breaking into a house - the former can take as long as for a star to explode, while the latter take ...
DannyNiu's user avatar
  • 9,080
13 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

At least two reasons. 1: security. You want your algorithm to be a good one. One of the best ways we know of ensuring cryptographic algorithms are good is to have as many experts as possible assess ...
ignis volens's user avatar
13 votes
Accepted

Impact of Ryan and Heninger's CRYPTO 2023 paper on post quantum cryptosystems

The following is mostly known to lattices people (and mentioned at the end of the Quanta article), but I also reached out to Keegan to clarify some questions I had. There are (roughly) two main types ...
Mark's user avatar
  • 12.5k
11 votes

Stuck on a cryptanalytical research project

The fact that your attack only works when you're using "normal math" and not "cryptographical math" (by which I assume you probably mean modular arithmetic, or perhaps arithmetic ...
Ilmari Karonen's user avatar
6 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

I think it most helpful to think of most cryptographic "algorithms" as being not algorithms directly, but rather algorithm factories, which use cryptographic keys as blueprints to produce ...
supercat's user avatar
  • 349
5 votes

How certain is it that a shorter password can't match the salted hash of a long one?

[originally posted on security.SE] There's a sister site, crypto.stackexchange.com, that might be better suited to answering your questions about the mathematical properties of hash functions. However,...
CBHacking's user avatar
  • 399
5 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

Because anyone can create a good secure key. Very few people can create create cryptographically secure encryption methods. Most likely, your 'secure encryption' is breakable, possibly by me, because ...
Questor's user avatar
  • 151
5 votes

Is it faster to decrypt than to encrypt in all cryptography systems?

In CBC and CFB modes, decryption can be parallelized, but encryption cannot. That's the most common reason for decryption being faster than encryption. But no, it is not faster to decrypt than to ...
fgrieu's user avatar
  • 140k
5 votes
Accepted

Can I change the radio frequency according to my encryption algorithm?

The answer to this is actually "yes", but it's generally not done due to encryption, it's done for the practicalities of RF. When you change frequencies, you often change the channel ...
b degnan's user avatar
  • 4,722
4 votes
Accepted

Confusion+Diffusion comparison table? (e.g. with Avalanche Criterion / SAC)

xor-streaming ciphers have no (0, zero, zilch) diffusion - you switch 1 bit in the ciphertext, you know which single bit in the plaintext after decryption will be flipped. Indeed, there is no ...
fgrieu's user avatar
  • 140k
4 votes
Accepted

Good references to breakable limits: $2^{60}$

We're generally aiming for a cryptographic strength of $2^{128}$ (i.e. close to $2^{128}$ operations are required to break a scheme). This is also called a cryptographic or security strength of 128 ...
Maarten Bodewes's user avatar
  • 92.4k
4 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

Brute force means trying possibilities until one works. If you use a single algorithm with a 128-bit key, there are $2^{128}$ possibilities for the attacker to test. If you choose between 16 different ...
benrg's user avatar
  • 756
4 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

The existing answers are good. Here's a way of looking at it that might fit your intuition better: I just read for a key length being around 128 bits of length results in 340,282,366,920,938,463,463,...
Ray Morris's user avatar
3 votes

Is Python secrets module using a unsafe RNG on Windows?

No. CryptGenRandom on Windows is deprecated as an API, but not for security reasons, rather because the whole cryptography API has been redesigned. The 2007 ...
Gilles 'SO- stop being evil''s user avatar
3 votes
Accepted

Are Schnorr's algorithm really subject to q-computer attacks?

The quantum Fourier transform is more powerful than a black box that returns the period of a cyclic group. A more general application is the hidden abelian subgroup problem. In the case of discrete ...
Daniel S's user avatar
  • 22.9k
3 votes
Accepted

What if LWE is not as secure as we think?

There are some alternatives. Mainly they fall into the categories of Coding-based crypto (LPN type things, McCliece, and rank metric codes) Isogeny-based crypto (though this has suffered devastating ...
Mark's user avatar
  • 12.5k
3 votes

Why was the Navajo code not broken by the Japanese in WWII?

The Japanese made efforts and could have broken Navajo code later in the War since Joe Kieyoomia didn't know teaching Navajo would damage the confidence of the code greatly. Even without his help, one ...
Schezuk's user avatar
  • 153
3 votes

Good references to breakable limits: $2^{60}$

On a practical note, a single consumer GPU (RTX4090) is capable of computing 164.1 GHashes/s of MD5. Note these are full MD5 computations, which of course are comprised of much more than a single ...
swineone's user avatar
  • 623
3 votes
Accepted

DDT for boolean functions must contain only powers of two

It is perfectly possible for the Difference Distribution Table (DDT) to have entries that are not powers of $2.$ There is no "reasonable" criterion that would rule this out that I am aware ...
kodlu's user avatar
  • 22.1k
3 votes

For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

You are standing right in front of the primary target house. You do not have the key with you but you know there are ways of getting in the home. You can either break the windows, use a crowbar, or ...
atk's user avatar
  • 131
3 votes

Double- and -add algorithm

The points of an elliptic curve forms an abelian group under the usual point addition. In finite field case, the order is finite, i.e. the curve has finite number of points. The order can be prime or ...
Titanlord's user avatar
  • 2,224
3 votes

Does combining a stream cipher and block cipher produce any vulnerabilities?

With respect to confidentiality, cascading two ciphers (xChacha20 then AES-CBC in the question) with independent keys is at least as secure as either cipher against KPA and CPA attacks. That's ...
fgrieu's user avatar
  • 140k
3 votes
Accepted

Judgment of Results from NIST Randomness Testing

1.) The pass/fail threshold is printed at the bottom of the finalAnalysisReport.txt file. It looks like:- The minimum pass rate for each statistical test with ...
Paul Uszak's user avatar
  • 15.3k
2 votes

Can neural cryptanalysis be applied to AES?

The problem of applied machine learning techniques on serious ciphers is that you don't have some good property like continuity which tells you when you are too far, a bit far or close to your ...
Victor Espinoza's user avatar
2 votes

Best Known Attacks on Discrete Logarithm in Generic Groups

The generic group model is an idealized cryptographic model for which an adversary only has access to a group oracle, which simulates a generic group of prime order. The intuition is that the group ...
Wilson's user avatar
  • 929
2 votes

Is there a quick way to know the length of a message hashed using SHA3?

No, there is no way to tell the message length from "the last block". Argument: however we define it, said last block is unchanged when we prepend a message with an additional $r$ bits of ...
fgrieu's user avatar
  • 140k
2 votes

Rule 30 based block cipher

Knowing a single plaintext/ciphertext pair $(p,c)$ at least as large as the password is enough to decipher any ciphertext $c'$ at least as large as $c$ encrypted with the same password. Just compute $...
fgrieu's user avatar
  • 140k
2 votes

Rule 30 based block cipher

There have been people considering CA for cryptanalysis. The problem is that CA leads to an unbounded state and this uses unbounded memory. Thus some dubious claims of "breaking" ...
kodlu's user avatar
  • 22.1k
2 votes

Stuck on a cryptanalytical research project

There is already a good answer. In addition, if you think actual cryptosystems used today are at risk but you believe "clock arithmetic" works makes me think actual (public key) ...
kodlu's user avatar
  • 22.1k

Only top scored, non community-wiki answers of a minimum length are eligible