# SHA256 Namespace for the SHA-256 hashing algorithm. ``` enum SHA256 ``` ## Overview `SHA256` exposes the canonical 32-byte / 256-bit digest defined by [FIPS PUB 180-4](https://csrc.nist.gov/publications/detail/fips/180/4/final) and [RFC 6234](https://datatracker.ietf.org/doc/html/rfc6234). It is suitable for integrity checks, HMAC-SHA256 key derivation, and content-addressed identifiers (JWT payload fingerprints, Nostr event IDs per NIP-01, and Git-style blob hashes). All entry points are `static` and live on this enum; the namespace is caseless and cannot be instantiated. Typical calls go through [`hash(data:)`](/documentation/OpenSSL/SHA256/hash(data:)) or [`hash(string:)`](/documentation/OpenSSL/SHA256/hash(string:)), both of which return a [`SHA256.SHA256Digest`](/documentation/OpenSSL/SHA256/SHA256Digest). > Note: Internally the implementation calls the legacy > [`SHA256_Init`](https://docs.openssl.org/3.6/man3/SHA256_Init/), > `SHA256_Update`, and `SHA256_Final` routines. Upstream marked these > deprecated in OpenSSL 3.0 in favor of the `EVP_MD` high-level > interface; this wrapper retains the legacy path for simplicity and > may migrate to `EVP_MD` in a future release with no public-API > change. > SeeAlso: ``doc://OpenSSL/documentation/OpenSSL/SHA256/hash(data:)``, ``doc://OpenSSL/documentation/OpenSSL/SHA256/hash(string:)``, > ``doc://OpenSSL/documentation/OpenSSL/SHA256/SHA256Digest``