# Questions tagged [implementation]

Implementing a cipher or protocol is the process of taking it from its mathematical or algorithmic description and producing a working version, often in computer software or hardware. This tag should be used for any question discussing the various potential considerations and pitfalls of this process, for example padding.

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### Question about error-Correction Code on Paper titled 'A New Public-Key Cryptosystem via Mersenne Number"

I've been implementing a cryptosystem outlined here, which relies on Mersenne Numbers, as part of my coursework in a Cryptography class. In this cryptosystem, both encryption and decryption require ...
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### improved impossible differential crpytanalysis of 6-round rijndael

I'm studying the paper: "Improved Impossible Differential Cryptanalysis of Rijndael and Crypton". I've got two questions: Please explain the calculation performed for step 5? Step 4 ...
1 vote
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### Kyber implementation possible overflow in the NTT subroutine?

I took a look at the code from Kyber, which I would like to quote here: ...
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### Matrix-vector multiplication in Kyber implementation

I took a look at the implementation of Kyber, which can be found in this GitRepo. I made a small discovery in the indcpa.c in the function indcpa_keypair, starting ...
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### Kyber - Compression and Decompression Implementation Example

I have a question about the implementation of the functions $$Compress_q(x,d) = \left\lfloor (2^d/q)\cdot x\right\rceil mod^{+}2^d$$ and $$Decompress_q(x,d) = \left\lfloor (q/2^d)\cdot x\right\rceil$$ ...
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### What efficiency can we expect from an average consumer computer for the RSA algorithm?

I am trying to implement the RSA algorithm using the C language, for learning purpose. I was wondering how much time should we expect it to take for encrypting a message of size 1024/2048/4096bits on ...
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### Problem with efficiency of projective coordinates in Elliptic Curve arithmetic

Ok sort of long post incoming. Will go slow to make it as clear as possible I'm trying to build a C library for Elliptic Curve Arithmetic. Since the idea is to learn from the process, I decided to ...
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### Has garbage-collection been used for side-channel attacks?

I'm thinking of cryptographic implementations on garbage-collected (gc) languages/runtimes and that the gc process can be potentially dangerous for an implementation even if the implementation has the ...
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### How do you securely implement a finite field?

I'm not sure if this question belongs here or to StackOverflow. Please flag it if not. I'm trying to implement a standalone library for finite field arithmetic of prime and prime power order as a way ...
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### Why is the constant in Montgomery Curve code 121665 instead of 486662 in the formula?

In the Montgomery Curve $y^2=x^3+486662x^2+x$, $A=486662$. So, why when applying its code in Python or another programming language, $A=121665$? ...
1 vote
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### Is an if-else calling same function(s) vulnerable to side channel attacks

If I have a function f(x, y) and g(x, y) and f and g a are constant time, is the following code vulnerable to side channel ...
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1 vote
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### Do you know any library for implementing lattice-based schemes? [closed]

Good afternoon! I'm trying to write a code for a lattice based scheme (based on the SIS problem). I'm looking for a library that may help me in this task without taking care of the implementation of ...
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1 vote
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The Golang implementation of edwards25519 (https://tip.golang.org/src/crypto/internal/edwards25519/field/fe.go) uses radix-251 representation. The description in section 3.2 in https://dl.acm.org/doi/...
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### Homomorphic Encryption and Conjugation

In the implementation of HEAAN, they have implemented the conjugate function. It computes conjugate of a polynomial. Effectively they have reverted the positions of the coefficients and negated their ...
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### Can attackers see the values I pass on to OpenSSL API functions?

Respected community, I am using the OpenSSL API's, especially libcrypto and libssl and I am really depressed, thinking about ...
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### Operands size in RSA Cryptography (C language)

I am trying to implement the RSA cryptography algorithm using C language. I am not sure of the size that each operand should have. Let me explain: RSA requires to generate two huge prime numbers p and ...
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1 vote
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### Browser javascript: TLS sequence number authentication

I am implementing TLS (or something like it perhaps) because the browser doesn't seem to provide a direct client-script interface to TLS. The browser provides a ...
1 vote
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### Good libraries for lattice-crypto [closed]

I'm searching good libraries to manipulate lattice tools to do cryptography. I'm mainly interested by C/C++. But I'm also interested if it is in python.
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### Make linkable ring signatures shorter?

I need a way to make the signatures shorter, currently with a ring size of 1000 members I get a signature size of 34000 bytes, this is too big for me I need a way to make it smaller. I tried ...
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