 ## BeeOS code static analysis

2018-04-06 | #os-dev #programming #security

BeeOS is a FOSS UNIX-like operating system focused on simplicity and POSIX compliance. The overall system is composed by four subprojects: The C standard library (libc) A utility user-space library (libu) Some user space applications (user) The kernel (kernel) This analysis targets the BeeOS kernel component

## Basic Encoding Rules

2017-11-10 | #encoding #standards

The Basic Encoding Rules for ASN.1 (BER) give one or more ways to represent any ASN.1 value as an octets sequence. There are three methods to encode an ASN.1 value under BER, the choice of which depends on the type of value and whether the length of the value is known.

## Feistel Ciphers

2017-11-07 | #cryptography

Feistel ciphers are a family of symmetric encryption algorithms that use repeated rounds of substitution and permutation operations on blocks of data to provide confidentiality and data integrity. Popular examples of Feistel ciphers include:

## Integer Overflow Detection

2017-11-07 | #programming #security

The following article is highly inspired by the work of Will Dietz, Peng Li, John Regehr, and Vikram Adve: ‘Understanding Integer Overflow in C/C++’. The work has been sliced down to the core and amended with some notes.

## Chinese Reminder Theorem

2017-10-02 | #cryptography #number-theory

The Chinese Remainder Theorem (CRT) is a mathematical theorem that provides a way to solve a system of linear congruences. Specifically, it states that given a set of integers that are pairwise coprime and a set of remainders modulo those integers, there exists a unique solution, modulo the product of the integers, to the system of congruences.

## RSA Cipher

2017-09-25 | #cryptography

Trivial Attempt Let’s first try to build a scheme directly using the Fermat’s Little Theorem. Given a prime number p and a message m < p, we choose two numbers e and d such that e·d = 1 (mod p-1).

## Euler's Totient

2017-08-19 | #mathematics #number-theory

Given a natural number n, the Euler φ function, also known as Euler’s Totient, applied to n represents the number of positive numbers less than n that are coprime to n.

## Unicode Math Symbols

2017-07-28 | #mathematics

A curated selection of essential mathematical symbols I found useful form my daily tasks. From calculus to greek letters. ∑ymbols ∫f Μath: ∀ ∃ ⊂🧮 ∩𝛍∀ ∑Σ, ♇𝛆Δ⇒⊢ ∃∀⇔ 𝛈𝜆𝛀⊆ ✍️🔢 ∃⇑ ∑𝚄𝚗𝚒𝚌𝚘𝚍𝚎’𝚜 ℝ𝕖⇧⊇📈 𝕋⊂⊆∈🔢

## Fermat's Little Theorem and Euler's Theorem

2017-07-23 | #mathematics #number-theory

Fermat’s Little theorem states that if p is a prime number and a is an integer not divisible by p, then a^(p-1) ≡ 1 (mod p). Euler’s theorem extends this to any positive integer n, stating that a^φ(n) ≡ 1 (mod n), where φ(n) is Euler’s totient function.