Cryptography Stack Exchange
Cryptography Stack Exchange

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.

546 questions
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Should a company ever implement a (recent) published cryptographic protocol

I understand that you should never, EVER, EVER implement your own unpublished cryptographic protocols. This topic has been well discussed in many places, e.g. here. However, once a protocol has been published, peer-reviewed and been around for a few…
D 1057129
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Cryptographic GUID?

I need a GUID. Really just any number that is likely to be unique. However I prefer not to leak time and other things as a GUID may leak. What should i use as a cryptographic replacement? I was thinking maybe i could use PBKDF2 using a GUID +…
user2651
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Library to find an addition chain for a large number?

I need a short addition chain for a number $n>2^{100}$ in order to implement a fast exponentiation. The memory footprint is not important. Finding an optimal chain for a large number $n$ is difficult (and considered by some to be an NP-complete…
Chris
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Proof of number of logins in last N days without saving login times

Let's say we have an user Bob. User Bob logs in into our web application every so often. We are a website that tries to save as little information about our users, however we'd like to know which users are inactive so we can suspend their…
TheRandomOne
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Minimal implementation of GPS identification algorithm from NESSIE project?

I'm studying GPS, asymmetric identification scheme from the NESSIE project. I found a bunch of helpful information about it in the original submission, they even mention minimal implementation examples (in C/GPS-C.pdf of submission archive). But…
OlegWock
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1 answer

Securely testing the presence of an item in a list without exposing the list

Not even sure what terms would describe what I'm looking for, but the general idea: Given a list of strings of a finite length, determine whether or not a test string belongs to the list. Then, produce a new list of strings containing the…
EAMann
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2 answers

Verify that a user submitted data without identifying which data was submitted

I'm not fully sure what the most accurate terms would be to describe what I'm looking for, but here's the gist: Let $u_1, \cdots, u_n$ be the users from a set of users $U$. Users may or may not submit some data $d_{u_1}, \cdots, d_{u_n}$ into my…
jdkula
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What are the algebraic normal forms for each bit of $z$, where $z = (x \oplus y) \oplus ((x \wedge y) \ll 1)$ (a non-linear operation in NORX)?

Let $x, y, z$ denote three $n$-bit words such that $$z = (x \oplus y) \oplus ((x \land y) \ll 1).$$ The NORX paper contains the generalized description of the algebraic normal forms for each bit of $x$ given $y$ and $z$: $$\begin{array}{l} x_0 =…
lyrically wicked
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Polynomial multiplication and division in $2^{128}$

I want to multiply and divide polynomials, and implement the extended Euclidean algorithm for polynomial greatest common divisors, over a Galois Field of size $2^{128}$. Moreover, I want to use the previous algorithms on an 8-bit microcontroller…
Herc11
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Hessian Curve Implementation

I tried implementing the Hessian form of an Elliptic curve over the prime field Fp where, p I have taken as 1051. The curve equation I took is $X^3 + Y^3 + cZ^3 = dXYZ$ with c = 1 and d = 6. Selected (4,2,6) as the base point. Followed the equation…
DEBASMITA DEY
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80-bit security and attack time

Many designer claimed that their cryptography scheme has 80-bit security. So how to calculate the time of attcking this 80-bit security cryptography scheme, such as 80-bit security RSA using a kind of CPU?
Alex Ideal
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Efficient polynomial ring multiplication with coefficients in GF(2^s)

Is there something similar (or an other efficient approach) to the NTT for the multiplication of polynomials in polynomial rings modulo $X^{2^n} + 1$ with coefficients in $\operatorname{GF}(p)$ with $p \equiv 1 \pmod{2^{n+1}}$, but instead for…
user51428
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Fermat's FFT based large integer multiplication

I was going through the documentation of GMP (https://gmplib.org/gmp-man-6.1.2.pdf), specially section 15.1.6 where they refer to the use of Fermat's style FFT. I tried to follow the reference but couldn't quite understand this technique, can…
ChanBan
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Implementing AES algorithm using Arduino

I am using an Arduino board to implement the AES Algorithm: I am having a large data of length approximately 500 bytes. I did all the basic stuff in implementing this AES Algorithm. I am getting partial Results. Please help me implement this.
Ramakrishna Dutt
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MISTY1 Implementation error

I am trying to implement MISTY1. It's RFC, RFC2994, contains psuedocode that I basically copy and pasted into Code::Blocks. However, I managed to mess that up somehow. After 2 days, I still have not figured out what i did wrong (Im probably being…
calccrypto
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