Cryptokit

Wraps Apple's CryptoKit framework for Swift apps targeting iOS 13+. Handles SHA256/384/512 hashing, HMAC authentication codes, AES-GCM and ChaChaPoly symmetric encryption, ECDSA signing with P256/P384/P521 curves plus Ed25519, ECDH key agreement, and Secure Enclave hardware key storage. The skill covers both one-shot and incremental operations, shows how to properly derive keys from shared secrets using HKDF, and includes authenticated encryption with additional data. CryptoKit is the modern replacement for CommonCrypto in Swift, so reach for this when you need production-grade crypto without wrestling with C APIs or managing your own constant-time comparisons.