sanitization-crypto-interop

Optional crypto crate integration helpers for sanitization.

This crate exists for projects migrating from direct zeroize usage to sanitization while still depending on third-party hash implementations whose internal state is only clearable through those crates' own zeroize features.

The core sanitization crate remains dependency-free by default. This sister crate is explicitly opt-in and feature-gated per backend. The optional std feature forwards to sanitization/std for callers that want the same feature profile across both crates; it is disabled by default.

[dependencies]
sanitization-crypto-interop = { version = "1.2.2", features = ["sha2", "blake3", "hmac-sha2"] }

SHA-2

The sha2 feature enables sha2's own zeroize support so hasher state is cleared by the upstream implementation when the hasher is dropped. The incremental wrapper types also implement sanitization::SecureSanitize.

The digest helper functions return ordinary arrays. If a digest is sensitive, clear it after use with sanitization::sanitize_bytes or move it directly into a sanitization secret container.

use sanitization_crypto_interop::sha2::sha512_digest;

let digest = sha512_digest(b"input");

BLAKE3

The blake3 feature enables blake3's own zeroize support and explicitly clears both the Hasher and XOF OutputReader after digest extraction. The incremental wrapper type also implements sanitization::SecureSanitize.

use sanitization_crypto_interop::blake3::blake3_xof_64;

let digest = blake3_xof_64(b"input");

Keyed BLAKE3 helpers are also available:

use sanitization_crypto_interop::blake3::blake3_keyed_xof_64;

let key = [7u8; 32];
let digest = blake3_keyed_xof_64(&key, b"input");

The caller remains responsible for clearing key material stored outside a sanitization secret container.

HMAC-SHA2

The hmac-sha2 feature enables HMAC-SHA256, HMAC-SHA384, and HMAC-SHA512 helpers built directly on SHA-2 with RAII sanitization of key-block, pad, and inner-digest scratch buffers, including panic-unwind cleanup. Prefer these helpers over manually building keyed SHA-2 by hashing key || message. Because this is a local RFC 2104 implementation, keep this module in audit scope for high-assurance deployments.

[dependencies]
sanitization-crypto-interop = { version = "1.2.2", features = ["hmac-sha2"] }

use sanitization_crypto_interop::hmac_sha2::hmac_sha256;

let tag = hmac_sha256(b"key", b"message");

Like digest helpers, returned tags are ordinary arrays and remain the caller's responsibility to clear if treated as sensitive. The caller also remains responsible for clearing HMAC key bytes held outside a sanitization secret container.

HKDF

HKDF helpers are intentionally not exposed yet. The current upstream hkdf crate stores PRK/HMAC state internally, and this crate will only wrap it after the cleanup path can be made explicit and tested the same way as the SHA-2, BLAKE3, and HMAC helpers.

Scope