sha256

sha256 is a small, ergonomic Rust crate that computes SHA-256 digests with a single digest() call. It accepts a wide range of inputs out of the box, strings, string slices, chars, and byte slices, and returns the hash as a lowercase hex string, removing the boilerplate normally required when working with lower-level hashing primitives.

Beyond the core function it offers try_digest for hashing file contents by path, an async digest API built on tokio for non-blocking hashing, and an optional OpenSSL-backed implementation for environments that prefer the system crypto library. It builds on the well-audited sha2 crate while presenting a far simpler surface.

What You Get

• A one-line digest() function that accepts strings, string slices, chars, and byte slices
• try_digest() for hashing the contents of a file by path
• An async digest API built on tokio for non-blocking hashing of large inputs
• An optional OpenSSL-backed implementation via the native_openssl feature
• Hex-encoded output returned directly as a String

Common Use Cases

• Computing content hashes for caching, deduplication, or integrity checks
• Fingerprinting file contents by path with try_digest
• Generating checksums asynchronously inside a tokio application
• Deriving deterministic identifiers from arbitrary input data

Under The Hood

Architecture - The crate centers on a Sha256Digest trait implemented for the supported input types, letting the free digest() function accept anything convertible to bytes and return a hex String. lib.rs holds the core sync path, async_digest.rs provides the tokio-backed async variant behind an async-trait, and openssl_sha256.rs supplies the optional OpenSSL implementation selected by feature flag. Hex encoding is delegated to the hex crate.

Tech Stack - Rust (edition 2018) built on the RustCrypto sha2 0.11 crate for the actual hashing, with hex for encoding, bytes for buffer handling, async-trait plus optional tokio for the async API, and optional openssl for the native backend. Features default = [async], plus native_openssl.

Code Quality - A dedicated tests.rs (142 lines) covers the digest and try_digest paths across the various input types shown in the README examples. The code is compact and single-purpose; the main complexity is the trait-based input overloading and the feature-gated backend selection.

API Design - The public surface is deliberately minimal and highly ergonomic: one digest() name works for every input type, try_digest() mirrors it for files, and output is a plain hex String, so first use requires essentially no learning beyond importing the function.