# Questions tagged [algorithm-design]

Design of cryptographic primitives (algorithms), like block ciphers, stream ciphers, random-number generators, hash functions, MACs, key exchanges, public-key encryption or signature schemes. Also tag with the relevant type of primitive. If you ask about a known existing algorithm, also tag with its name.

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48 views

### What papers describe the rationale behind cryptography algorithms

I am trying to introduce myself to cryptographic hashing and encryption. I am looking for original papers of sorts, to describe the inspiration behind why they choose certain numbers, if they are ...
96 views

### Montgomery Multiplication with CRT

I am attempting to understand how to use Montgomery multiplication in an RSA private key operation: $X \equiv a^{e} \pmod{n}$ where $a$ is the message, $e$ is the exponent, $n$ is the modulus. Using ...
23 views

### Designing number of rounds of specific hashing process [closed]

Consider a certain encryption process/hash function which transform 128-bit blocks into 128-bit blocks. This is not a cipher or complete function yet. I am thinking about the theoretical process. We ...
120 views

### What's the name of this random number generation algorithm?

I'm looking for the name of an RNG method or algorithm, described below. Combining multiple results of a non-uniform random number generator can produce a more uniform result. It seems like this would ...
46 views

### How to design number of rounds in my cipher?

I have specific cipher which is built from permutations. It has or should has few rounds. If we do 2 rounds it is like 2 permutation composition. 3 rounds are like composition of 3 permutations and so ...
100 views

### Cryptographic function that can 'pack' numbers

Is there a cryptographic algorithm that can 'pack' a bunch of strings/numbers and "confirm" if a string/numbers exists (later in the code) while keeping the output hidden? For example, I have ...
69 views

### How to construct a “toy” version of the Ascon permutation?

I want to obtain a “toy” version of the Ascon permutation defined for five 8-bit words (instead of five 64-bit words.) It seems that it is possible to use the same bit-sliced 5-bit S-Box. But is it ...
28 views

### Are there popular and secure Authenticated Encryption schemes with Salsa20/Sosemanuk in CTR-mode with a Carter-Wegman MAC?

I read that AES/GCM is a good choice for authenticated encryption because: AES has very strong heuristic security Encrypt-then-MAC leaks no information about the plaintext The CW-MAC in GCM can be ...
38 views

### Help on validation code algorithm [closed]

I wonder if someone can help me find the algorithm used to generate validation codes from a serial number. I already have some working examples of serials->codes pairs: 19003148 -> 523254 19003162 -...
114 views

### Error correcting codes that are indistinguishable from random

Suppose you have a public program P(n) which takes message n and generates an encrypted output (utilizing asymmetric cryptography) for some entity which has the private key to decrypt it. Using a ...
35 views

### Approach used with XOR cipher in black box scenery

What's the approach used in cryptanalysis to make an decrypter for a simple xor stream cipher in a Black Box scenery with only the output?
26 views

### How to determine the maximum number of times the DES algorithm needs to be run?

I am only a beginner in cryptography and I am getting confused by the following: Question Consider a known-plaintext attack performed on a double-DES cryptosystem. (a) Determine the maximum number ...
47 views

### Multiparty dataset intersection count

Typically, Private Set Intersection (PSI) protocols let you learn the subset of items on each party's dataset that are in the intersection. The problem in this case is a relaxation of these kind of ...
55 views

### How to calculate RSA Key Size correctly starting from 384 bits to 15360 bits or beyond 15360 bits

Hello fellow experts here, I am new to cryptography. Recently I looked into RSA Key Size (Microsoft RSA library), it actually describes that the minimal key length required is 384 bits and maximum ...
31 views

### How to calculate degree of confusion of an encryption algorithm?

I am programming an encryption-decryption model in python 3. I want to check its strength. I found 3 methods to check, they are: 1. Degree of diffusion 2. Degree of confusion 3. Integrity check For ...
29 views

### Can MFA codes be predicted if you know what their values were at a previous time?

I use an app on my phone that, after scanning a QR code on a website, gives me 6-digit codes which change every 30 seconds. These codes can be used for Multi-Factor Authentication (MFA) on some ...