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2 votes

Is it possible to create a mix of predefined and generated shares for Shamir's Secret Sharing?

As Daniel S notes this is certainly possible, in the sense that the math behind Shamir's secret sharing allows you to arbitrarily choose up to $k$ of the field points that the polynomial will be ...
Ilmari Karonen's user avatar
0 votes

Is it possible to make time-locked encrytion algorithm?

The pseudonymous giant, Gwern, has written a lovely survey paper on this topic that stretches from Rivest to Vitalik and beyond. It's an excellent starting point if you want to get a broad overview. ...
JamesTheAwesomeDude's user avatar
4 votes

Is it possible to create a mix of predefined and generated shares for Shamir's Secret Sharing?

This is certainly possible. Given a threshold of $k$, we can set $k-1$ shares to be arbitrary and then determine the remaining shares. This is a natural consequence of all possible secrets being ...
Daniel S's user avatar
  • 22.8k
0 votes

Is it possible to make time-locked encrytion algorithm?

You can use drand, which is backed by companies like cloudflare. Here is a live demo
Fawaz Ahmed's user avatar
1 vote

Devising a system that allows for aggregate computations but does not hold the single values

One common approach to deal with these kinds of questions is differential privacy, google it. A search here on crypto stackexchange yields quite a lot of questions and answers. Very briefly and in its ...
kodlu's user avatar
  • 21.9k
2 votes
Accepted

Are there asymmetric encryption algorithms that preserve equality? Are they safe to use for data obfuscation?

Are there asymmetric encryption algorithms that preserve equality? As explained in @poncho's answer, that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to ...
fgrieu's user avatar
  • 140k
2 votes

Are there asymmetric encryption algorithms that preserve equality? Are they safe to use for data obfuscation?

A trusted party must have the ability to reverse the obfuscation. We will call that party Admin. We need some form of encryption. I don't find that the OP makes a compelling argument to support ...
J_H's user avatar
  • 262
1 vote

Are there asymmetric encryption algorithms that preserve equality? Are they safe to use for data obfuscation?

This sounds like you’re trying to solve two different requirements, so wrt separation of concerns, one approach would be to divide the implementation into an obfuscation of the data through encryption ...
not2savvy's user avatar
  • 220
2 votes

Are there asymmetric encryption algorithms that preserve equality? Are they safe to use for data obfuscation?

It sounds like you are looking for 'deterministic public key encryption'. We typically don't recommend it, precisely because it preserves equality. That is, someone with the the public key and a ...
poncho's user avatar
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0 votes

Enigma encryption

Why not? I'll rephrase your question as "Now imagine the $\mathtt{G}$ key is pressed and returns to the plugboard as, say, a $\mathtt{Q}$. But what then happens if, on the plugboard, the $\mathtt{...
Chan Tai Man's user avatar
4 votes

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
  • 4,697
2 votes

The cost of the additive homomorphic encryption of McEliece cryptosystem

You should decrypt and add. Let us take a simple McEliece set up where the public key is $k\times n$ matrix $\hat G$ and a $k$-long bit vector $\mathbf m$ is encrypted as $\mathbf m\hat G\oplus \...
Daniel S's user avatar
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2 votes

Enigma encryption

Short answer: Enigma, with or without a plugboard, is self-inverse and never encode to itself. If $\mathtt{A}$ maps to $\mathtt{W}$, for the same machine state $\mathtt{W}$ maps to $\mathtt{A}$. ...
Chan Tai Man's user avatar
2 votes

Enigma encryption

Here is a partial Enigma schematic showing only 4 keys and light-bulbs, and 6 contacts per reflector (UKW), rotor side, and plug-board (Stecker) side (out of 26 due to space limitation). Simplified ...
fgrieu's user avatar
  • 140k
3 votes

Enigma encryption

What you missed is that the signal goes through the plugboard twice. Quoting Wikipedia: Current flows from the battery (1) through a depressed bi-directional keyboard switch (2) to the plugboard (3). ...
Eugene Styer's user avatar
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15 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
  • 21.9k
4 votes

What best to put in unused nonce bytes when using AES-GCM-SIV

In short yes, nonces just need to be unique. Just zeroing "leftover" bytes is fine if your protocol can guarantee uniqueness with fewer bytes. In protocols the zero bytes are often ...
Maarten Bodewes's user avatar
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1 vote
Accepted

Can HKDF be safely used as a round function in a Feistel Cipher

I didn't look too closely at the code for all issues. But in general, you could use HKDF to implement a Feistel cipher for the sake of an experiment. The way this is implemented currently uses HKDF ...
Marc Ilunga's user avatar
  • 3,163
0 votes

Which encryption method supports random reads?

ChaCha20 is a stream cipher supporting arbitrary seeking (and is considered secure enough to be recommended in TLS since v1.3). In terms of memory consumption and time-performance, For input, it ...
starball's user avatar
  • 109
0 votes
Accepted

Is there any format-prolongation encryption?

Just noticed AES can be used after adding some extra (randomized) bits. Thanks for the hint! We start with a 128-bit message and add $n$ extra (random) bits at the end of it. We first apply AES to the ...
UncleBob's user avatar
1 vote
Accepted

Chaos theory combined with RSA and/or other cryptosystems?

Or, a better way to put it.. are there obvious drawbacks with chaotic functions when using them for cryptographic purposes? The obvious drawback is that it adds an unclear amount of value, while ...
Mark's user avatar
  • 12.4k
2 votes

What weaknesses are worth investigating in this non-linear matrix cipher?

As poncho mentioned, your cipher is linear. You seemed initially to think that it was quadratic. This is just an answer to say that it is well-known that your equation can be rewritten to be of the ...
Mark's user avatar
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3 votes
Accepted

What weaknesses are worth investigating in this non-linear matrix cipher?

Well, with this cipher, we have: $$\mathcal{E}(p) + \mathcal{E}(q) = \mathcal{E}(p+q)$$ (and the addition operation is adding the matrix elements modulo 256) That is, it is linear; the standard linear ...
poncho's user avatar
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0 votes

Can you re-encrypt data without knowing what the data is or using PRE?

The ability of re-encrypting the data to arbitrary public key implies the ability of decryption. So, you can simply upload your secret key in a secret-shared form to your network nodes. With consensus,...
vince.h's user avatar
  • 117
0 votes

my ciphertext and original message look like they are two different sizes

AES is a block cipher which is a process that takes as input a fixed number of bits (known as the block size) and outputs the same number of bits. For AES, the block size is 128-bits or 16-bytes. When ...
Daniel S's user avatar
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2 votes
Accepted

Keygen with timelock encryption so that the secret key is hidden from everyone?

The scheme proposed in the question looks reasonably possible but might require getting some details right and thinking more carefully about the desired security guarantees. On the other hand, it is ...
Marc Ilunga's user avatar
  • 3,163
2 votes
Accepted

Cartesian Product Notation for Encryption and Decryption

This is a function mapping notation. A Cartesian product doesn't mean that the map is multiplication. The encryption map $E$ is from the space $\cal K \times \cal M$ to the space $C$. So we have a map ...
kodlu's user avatar
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