#rsa

Modular-arithmetic maths as an API, computed locally and deterministically with exact big-integer arithmetic. The power endpoint computes modular exponentiation, aᵇ mod m, by square-and-multiply, fast and exact even for the huge exponents used in cryptography. The inverse endpoint finds the modular multiplicative inverse a⁻¹ mod m with the extended Euclidean algorithm, returning the inverse when a and m are coprime and reporting the gcd when no inverse exists. The totient endpoint computes Euler's totient φ(n) — the count of integers from 1 to n coprime to n — with the prime factorization it comes from, and an optional Euler-theorem check that a^φ(n) ≡ 1 (mod n) for a coprime base. These are the building blocks of RSA and much of modern cryptography. Inputs are integers and can be passed as strings for very large values. Everything is computed locally and deterministically, so it is instant and private. Ideal for cryptography, security, blockchain and mathematics app developers, RSA and number-theory tools, and computer-science education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is modular arithmetic; for prime factorization and GCD use a number-theory API and for integer sequences a sequences API.

api.oanor.com/modular-api

Generate cryptographic key pairs on demand — RSA (2048/3072/4096), elliptic-curve (P-256, P-384, P-521, secp256k1), Ed25519 and Ed448 — returned as PEM (SPKI public key, PKCS#8 private key) and, optionally, as JWK. Perfect for spinning up JWT/JWS signing keys, TLS and SSH experiments, test fixtures and demos. Pure local generation with Node's crypto (no third-party service). Note: for development, testing and education — generate keys for production systems offline or in an HSM, never trust a remote API with real private keys. Live, nothing stored. 3 endpoints. Distinct from JWT signing, password generation and hashing.

api.oanor.com/keypair-api