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diff --git a/vendor/hkdf/README.md b/vendor/hkdf/README.md new file mode 100644 index 000000000..76efd86e1 --- /dev/null +++ b/vendor/hkdf/README.md @@ -0,0 +1,85 @@ +# RustCrypto: HKDF + +[![crate][crate-image]][crate-link] +[![Docs][docs-image]][docs-link] +![Apache2/MIT licensed][license-image] +![Rust Version][rustc-image] +[![Project Chat][chat-image]][chat-link] +[![Build Status][build-image]][build-link] + +Pure Rust implementation of the [HMAC-based Extract-and-Expand Key Derivation Function (HKDF)](https://tools.ietf.org/html/rfc5869) generic over hash function. + +# Usage + +The most common way to use HKDF is as follows: you provide the Initial Key Material (IKM) and an optional salt, then you expand it (perhaps multiple times) into some Output Key Material (OKM) bound to an "info" context string. + +```rust +use sha2::Sha256; +use hkdf::Hkdf; +use hex_literal::hex; + +let ikm = hex!("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b"); +let salt = hex!("000102030405060708090a0b0c"); +let info = hex!("f0f1f2f3f4f5f6f7f8f9"); + +let hk = Hkdf::<Sha256>::new(Some(&salt[..]), &ikm); +let mut okm = [0u8; 42]; +hk.expand(&info, &mut okm) + .expect("42 is a valid length for Sha256 to output"); + +let expected = hex!(" + 3cb25f25faacd57a90434f64d0362f2a + 2d2d0a90cf1a5a4c5db02d56ecc4c5bf + 34007208d5b887185865 +"); +assert_eq!(okm, expected); +``` + +Normally the PRK (Pseudo-Random Key) remains hidden within the HKDF object, but if you need to access it, use `Hkdf::extract` instead of `Hkdf::new`. + +```rust +let (prk, hk) = Hkdf::<Sha256>::extract(Some(&salt[..]), &ikm); +let expected = hex!(" + 077709362c2e32df0ddc3f0dc47bba63 + 90b6c73bb50f9c3122ec844ad7c2b3e5 +"); +assert_eq!(prk[..], expected[..]); +``` + +If you already have a strong key to work from (uniformly-distributed and +long enough), you can save a tiny amount of time by skipping the extract +step. In this case, you pass a Pseudo-Random Key (PRK) into the +`Hkdf::from_prk` constructor, then use the resulting `Hkdf` object +as usual. + +```rust +let prk = hex!(" + 077709362c2e32df0ddc3f0dc47bba63 + 90b6c73bb50f9c3122ec844ad7c2b3e5 +"); + +let hk = Hkdf::<Sha256>::from_prk(&prk).expect("PRK should be large enough"); +let mut okm = [0u8; 42]; +hk.expand(&info, &mut okm) + .expect("42 is a valid length for Sha256 to output"); + +let expected = hex!(" + 3cb25f25faacd57a90434f64d0362f2a + 2d2d0a90cf1a5a4c5db02d56ecc4c5bf + 34007208d5b887185865 +"); +assert_eq!(okm, expected); +``` + +[//]: # (badges) + +[crate-image]: https://img.shields.io/crates/v/hkdf.svg +[crate-link]: https://crates.io/crates/hkdf +[docs-image]: https://docs.rs/hkdf/badge.svg +[docs-link]: https://docs.rs/hkdf/ +[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg +[rustc-image]: https://img.shields.io/badge/rustc-1.41+-blue.svg +[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg +[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/260043-KDFs +[build-image]: https://github.com/RustCrypto/KDFs/workflows/hkdf/badge.svg?branch=master&event=push +[build-link]: https://github.com/RustCrypto/KDFs/actions?query=workflow:hkdf |