maths.free › Number Theory › RSA: cryptography from number theory

RSA: cryptography from number theory

Public keys from two primes, and why factoring is the lock.

Choose primes p, q; n = pq; pick e coprime to φ(n) = (p − 1)(q − 1); the private key d is e⁻¹ mod φ(n). Encrypt mᵉ mod n, decrypt with d. The security is the difficulty of factoring n. Picture it: a padlock anyone can snap shut (e) that only the key (d) opens. Think it: correctness is Euler's theorem; the whole scheme is one modular inverse.

Apdorotas pavyzdys · inverse of 17 mod 3120

Number-Theory · Modular-Arithmetic

Inverse of 17 mod 3120

17,\ 3120

Žingsnis po žingsnio

  1. 17x \equiv 1 \pmod{3120}

    We want x with a·x ≡ 1 (mod m). It exists only when gcd(a, m) = 1.

  2. 3120 = 183 \times 17 + 9

    Euclid step.

  3. 17 = 1 \times 9 + 8

    Euclid step.

  4. 9 = 1 \times 8 + 1

    Euclid step.

  5. 8 = 8 \times 1 + 0

    Euclid step.

  6. 17 \times 2753 = 46801 \equiv 1 \pmod{3120}

    Back-substitute (extended Euclid) to express 1 as a combination of a and m; the coefficient of a is the inverse.

Atskleisti atsakymą
17^{-1} \equiv 2753 \pmod{3120}

Dabar tu Pasirinkite problemą, arba įveskite ar piešti savo. Kiekvienas žingsnis, paveikslas, atsakymas paslėptas, kol jūs klausiate.

Išlaikyti savo darbą

Nemokama paskyra prideda pastabas apie kiekvieną pamoką, įrašą apie tai, ką baigėte, savo išspręstas problemas vienoje vietoje ir mokytoją, kurį galite paklausti apie šį puslapį. Pati matematika yra atvira visiems, kurie yra ar nėra užsiregistravę.

Prisijungti Prisijungti

Čia naudojami simboliai

Bakstelėkite visus simbolius, kad būtų galima apibrėžti visą apibrėžimą, paveikslėlį ir ką reiškia kiekviena raidė.

Kaip vartoti: RSA: cryptography from number theory

  1. We want x with a·x ≡ 1 (mod m). It exists only when gcd(a, m) = 1.
  2. Euclid step.
  3. Euclid step.
  4. Euclid step.
  5. Euclid step.
  6. Back-substitute (extended Euclid) to express 1 as a combination of a and m; the coefficient of a is the inverse.

Klausimai, kuriuos klausia žmonės

Why are primes so important?

Every integer factors into primes in exactly one way, so primes are the atoms of multiplication. Cryptography relies on that factoring being easy to state and hard to do.

How do I tell whether a big number is prime?

Trial division up to the square root works for small numbers. For large ones, probabilistic tests (Miller-Rabin) give an answer that is wrong with negligible probability, and deterministic tests (AKS) exist but are slower.

Daugiau informacijos Number Theory

Prime factorisationPrime numbersGCD and LCMModular arithmeticDivisorsSequencesNumber basesDiophantine equationsFermat's little theorem and Euler's theorem