ic-kdf 0.2.8

HKDF, PBKDF2, and SP 800-108 key derivation for IronCrypto
Documentation 
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//! # ic-kdf — key derivation
//!
//! * [`hkdf`] — RFC 5869 extract-and-expand (SP 800-56C two-step).
//! * [`pbkdf2()`] — SP 800-132 password-based derivation.
//! * [`kbkdf`] — SP 800-108 counter-mode KDF over HMAC.
//! * [`argon2()`] — RFC 9106 memory-hard password hashing.
//!
//! The HMAC-based functions are generic over the instantiation, so the same
//! code path serves SHA-256, SHA-384, SHA-512, and the SHA-3 family.
//!
//! ## Choosing between the two password KDFs
//!
//! [`pbkdf2()`] is the only *approved* option and is not memory-hard, so a GPU
//! attacks it far faster than a CPU defends it. [`argon2()`] is memory-hard and
//! is what RFC 9106 recommends, but is not FIPS-approved. If you have a FIPS
//! obligation the choice is made for you; otherwise reach for Argon2id.
//!
//! ```
//! use ic_kdf::hkdf::Hkdf;
//! use ic_core::traits::Kdf;
//! use ic_mac::HmacSha256;
//!
//! let mut key = [0u8; 32];
//! Hkdf::<HmacSha256>::derive(b"input keying material", b"salt", b"app v1", &mut key)?;
//! # Ok::<(), ic_core::Error>(())
//! ```
#![cfg_attr(not(feature = "std"), no_std)]
#![forbid(unsafe_code)]
#![deny(missing_docs)]
#![warn(clippy::all)]

// Argon2 needs a large contiguous arena, so it is the one KDF here that
// requires an allocator — `alloc`, not the whole standard library, so it still
// builds for bare-metal targets that provide a global allocator.
extern crate alloc;

pub mod argon2;
pub mod hkdf;
pub mod kbkdf;
pub mod pbkdf2;

pub use argon2::{argon2, Argon2Params, Variant};
pub use hkdf::Hkdf;
pub use kbkdf::kbkdf_counter;
pub use pbkdf2::pbkdf2;

/// Ontology identifiers for the KDFs this crate provides.
pub const KDF_IDS: &[&str] = &[
    "argon2id",
    "hkdf-sha2-256",
    "hkdf-sha2-384",
    "hkdf-sha2-512",
    "pbkdf2-hmac-sha2-256",
    "pbkdf2-hmac-sha2-512",
    "sp800-108-counter-hmac-sha2-256",
];

/// The SP 800-132 floor for PBKDF2 iterations in new deployments.
///
/// SP 800-132 sets 1 000 as an absolute minimum; OWASP and the CMVP guidance
/// for modern hardware put the practical floor far higher. An agent that
/// derives a password-based key below this is warned by
/// [`pbkdf2::check_iterations`].
pub const PBKDF2_MIN_RECOMMENDED_ITERATIONS: u32 = 600_000;