10 Services from crypto-math.x402tookit.com

Generate or validate Luhn and ISO 7064 mod 97-10 (IBAN-style) check digits for a given numeric or alphanumeric string.

Computes GCD, LCM, and extended Euclidean Bézout coefficients for two integers, with optional batch GCD/LCM over up to 20 additional numbers.

Solves systems of simultaneous congruences (x ≡ a1 mod m1, x ≡ a2 mod m2, …) using the Chinese Remainder Theorem, supporting both coprime and non-coprime moduli.

Computes base^exp mod m for big integers (up to 4096 bits), accepting decimal or 0x hex inputs, returning both decimal and hex results.

Convert public byte strings between hex, base64, and base64url (RFC 4648) with strict decoding and optional expected-length verification.

Runs a deterministic Miller-Rabin primality test on a big integer (up to 1024 bits), plus optionally returns the nearest previous and next primes.

Computes Shannon entropy, min-entropy, collision entropy, and efficiency in bits per symbol from a frequency table of counts or probabilities.

Computes the modular multiplicative inverse of a mod m, or returns the GCD proving no inverse exists when gcd(a,m) > 1.

Returns the SEC 2 public domain parameters (p, n, G, a, b) for secp256k1, P-256, or P-384, and optionally validates whether a given public point lies on the specified curve.

Analyzes RSA public key parameters (modulus bits, exponent validity, NIST strength) or demonstrates a toy RSA encryption/decryption round-trip using tiny primes.