RSA is a public-key encryption scheme in number theory built on modular arithmetic, congruence, and the multiplicative inverse, whose security rests on the computational hardness of factoring the product of two large primes. Its correctness follows from Euler's totient function and Euler's theorem (k^φ(n) ≡ 1 mod n for k relatively prime to n), specialized to Fermat's little theorem when n is prime, which together guarantee that raising a message to the public exponent and then to the secret exponent modulo n recovers the original message. The scheme belongs to public-key cryptography, distinguishing itself from shared-secret-key schemes by allowing encryption and decryption keys to be mathematically related yet computationally infeasible to derive one from the other without factoring the modulus.
RSA is a public-key encryption scheme in number theory built on modular arithmetic, congruence, and the multiplicative inverse, whose security rests on the computational hardness of factoring the pro…