| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/git/checkouts/incubator-teaclave-crates-c8106113f74feefc/ede1f68/ring/src/hkdf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>hkdf.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../ring/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../ring/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="comment">// Copyright 2015 Brian Smith. |
| // |
| // Permission to use, copy, modify, and/or distribute this software for any |
| // purpose with or without fee is hereby granted, provided that the above |
| // copyright notice and this permission notice appear in all copies. |
| // |
| // THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES |
| // WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| // MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY |
| // SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| // WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
| // OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| |
| </span><span class="doccomment">//! HMAC-based Extract-and-Expand Key Derivation Function. |
| //! |
| //! HKDF is specified in [RFC 5869]. |
| //! |
| //! [RFC 5869]: https://tools.ietf.org/html/rfc5869 |
| |
| </span><span class="kw">use crate</span>::{error, hmac}; |
| |
| <span class="doccomment">/// An HKDF algorithm. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug, Eq, PartialEq)] |
| </span><span class="kw">pub struct </span>Algorithm(hmac::Algorithm); |
| |
| <span class="kw">impl </span>Algorithm { |
| <span class="doccomment">/// The underlying HMAC algorithm. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>hmac_algorithm(<span class="kw-2">&</span><span class="self">self</span>) -> hmac::Algorithm { |
| <span class="self">self</span>.<span class="number">0 |
| </span>} |
| } |
| |
| <span class="doccomment">/// HKDF using HMAC-SHA-1. Obsolete. |
| </span><span class="kw">pub static </span>HKDF_SHA1_FOR_LEGACY_USE_ONLY: Algorithm = |
| Algorithm(hmac::HMAC_SHA1_FOR_LEGACY_USE_ONLY); |
| |
| <span class="doccomment">/// HKDF using HMAC-SHA-256. |
| </span><span class="kw">pub static </span>HKDF_SHA256: Algorithm = Algorithm(hmac::HMAC_SHA256); |
| |
| <span class="doccomment">/// HKDF using HMAC-SHA-384. |
| </span><span class="kw">pub static </span>HKDF_SHA384: Algorithm = Algorithm(hmac::HMAC_SHA384); |
| |
| <span class="doccomment">/// HKDF using HMAC-SHA-512. |
| </span><span class="kw">pub static </span>HKDF_SHA512: Algorithm = Algorithm(hmac::HMAC_SHA512); |
| |
| <span class="kw">impl </span>KeyType <span class="kw">for </span>Algorithm { |
| <span class="kw">fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.<span class="number">0</span>.digest_algorithm().output_len |
| } |
| } |
| |
| <span class="doccomment">/// A salt for HKDF operations. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>Salt(hmac::Key); |
| |
| <span class="kw">impl </span>Salt { |
| <span class="doccomment">/// Constructs a new `Salt` with the given value based on the given digest |
| /// algorithm. |
| /// |
| /// Constructing a `Salt` is relatively expensive so it is good to reuse a |
| /// `Salt` object instead of re-constructing `Salt`s with the same value. |
| </span><span class="kw">pub fn </span>new(algorithm: Algorithm, value: <span class="kw-2">&</span>[u8]) -> <span class="self">Self </span>{ |
| Salt(hmac::Key::new(algorithm.<span class="number">0</span>, value)) |
| } |
| |
| <span class="doccomment">/// The [HKDF-Extract] operation. |
| /// |
| /// [HKDF-Extract]: https://tools.ietf.org/html/rfc5869#section-2.2 |
| </span><span class="kw">pub fn </span>extract(<span class="kw-2">&</span><span class="self">self</span>, secret: <span class="kw-2">&</span>[u8]) -> Prk { |
| <span class="comment">// The spec says that if no salt is provided then a key of |
| // `digest_alg.output_len` bytes of zeros is used. But, HMAC keys are |
| // already zero-padded to the block length, which is larger than the output |
| // length of the extract step (the length of the digest). Consequently the |
| // `Key` constructor will automatically do the right thing for a |
| // zero-length string. |
| </span><span class="kw">let </span>salt = <span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>; |
| <span class="kw">let </span>prk = hmac::sign(salt, secret); |
| Prk(hmac::Key::new(salt.algorithm(), prk.as_ref())) |
| } |
| |
| <span class="doccomment">/// The algorithm used to derive this salt. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>algorithm(<span class="kw-2">&</span><span class="self">self</span>) -> Algorithm { |
| Algorithm(<span class="self">self</span>.<span class="number">0</span>.algorithm()) |
| } |
| } |
| |
| <span class="kw">impl </span>From<Okm<<span class="lifetime">'_</span>, Algorithm>> <span class="kw">for </span>Salt { |
| <span class="kw">fn </span>from(okm: Okm<<span class="lifetime">'_</span>, Algorithm>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(hmac::Key::from(Okm { |
| prk: okm.prk, |
| info: okm.info, |
| len: okm.len().<span class="number">0</span>, |
| len_cached: okm.len_cached, |
| })) |
| } |
| } |
| |
| <span class="doccomment">/// The length of the OKM (Output Keying Material) for a `Prk::expand()` call. |
| </span><span class="kw">pub trait </span>KeyType { |
| <span class="doccomment">/// The length that `Prk::expand()` should expand its input to. |
| </span><span class="kw">fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize; |
| } |
| |
| <span class="doccomment">/// A HKDF PRK (pseudorandom key). |
| </span><span class="attribute">#[derive(Clone, Debug)] |
| </span><span class="kw">pub struct </span>Prk(hmac::Key); |
| |
| <span class="kw">impl </span>Prk { |
| <span class="doccomment">/// Construct a new `Prk` directly with the given value. |
| /// |
| /// Usually one can avoid using this. It is useful when the application |
| /// intentionally wants to leak the PRK secret, e.g. to implement |
| /// `SSLKEYLOGFILE` functionality. |
| </span><span class="kw">pub fn </span>new_less_safe(algorithm: Algorithm, value: <span class="kw-2">&</span>[u8]) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(hmac::Key::new(algorithm.hmac_algorithm(), value)) |
| } |
| |
| <span class="doccomment">/// The [HKDF-Expand] operation. |
| /// |
| /// [HKDF-Expand]: https://tools.ietf.org/html/rfc5869#section-2.3 |
| /// |
| /// Fails if (and only if) `len` is too large. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>expand<<span class="lifetime">'a</span>, L: KeyType>( |
| <span class="kw-2">&</span><span class="lifetime">'a </span><span class="self">self</span>, |
| info: <span class="kw-2">&</span><span class="lifetime">'a </span>[<span class="kw-2">&</span><span class="lifetime">'a </span>[u8]], |
| len: L, |
| ) -> <span class="prelude-ty">Result</span><Okm<<span class="lifetime">'a</span>, L>, error::Unspecified> { |
| <span class="kw">let </span>len_cached = len.len(); |
| <span class="kw">if </span>len_cached > <span class="number">255 </span>* <span class="self">self</span>.<span class="number">0</span>.algorithm().digest_algorithm().output_len { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| <span class="prelude-val">Ok</span>(Okm { |
| prk: <span class="self">self</span>, |
| info, |
| len, |
| len_cached, |
| }) |
| } |
| } |
| |
| <span class="kw">impl </span>From<Okm<<span class="lifetime">'_</span>, Algorithm>> <span class="kw">for </span>Prk { |
| <span class="kw">fn </span>from(okm: Okm<Algorithm>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(hmac::Key::from(Okm { |
| prk: okm.prk, |
| info: okm.info, |
| len: okm.len().<span class="number">0</span>, |
| len_cached: okm.len_cached, |
| })) |
| } |
| } |
| |
| <span class="doccomment">/// An HKDF OKM (Output Keying Material) |
| /// |
| /// Intentionally not `Clone` or `Copy` as an OKM is generally only safe to |
| /// use once. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>Okm<<span class="lifetime">'a</span>, L: KeyType> { |
| prk: <span class="kw-2">&</span><span class="lifetime">'a </span>Prk, |
| info: <span class="kw-2">&</span><span class="lifetime">'a </span>[<span class="kw-2">&</span><span class="lifetime">'a </span>[u8]], |
| len: L, |
| len_cached: usize, |
| } |
| |
| <span class="kw">impl</span><L: KeyType> Okm<<span class="lifetime">'_</span>, L> { |
| <span class="doccomment">/// The `OkmLength` given to `Prk::expand()`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>L { |
| <span class="kw-2">&</span><span class="self">self</span>.len |
| } |
| |
| <span class="doccomment">/// Fills `out` with the output of the HKDF-Expand operation for the given |
| /// inputs. |
| /// |
| /// Fails if (and only if) the requested output length is larger than 255 |
| /// times the size of the digest algorithm's output. (This is the limit |
| /// imposed by the HKDF specification due to the way HKDF's counter is |
| /// constructed.) |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>fill(<span class="self">self</span>, out: <span class="kw-2">&mut </span>[u8]) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| fill_okm(<span class="self">self</span>.prk, <span class="self">self</span>.info, out, <span class="self">self</span>.len_cached) |
| } |
| } |
| |
| <span class="kw">fn </span>fill_okm( |
| prk: <span class="kw-2">&</span>Prk, |
| info: <span class="kw-2">&</span>[<span class="kw-2">&</span>[u8]], |
| out: <span class="kw-2">&mut </span>[u8], |
| len: usize, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">if </span>out.len() != len { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| |
| <span class="kw">let </span>digest_alg = prk.<span class="number">0</span>.algorithm().digest_algorithm(); |
| <span class="macro">assert!</span>(digest_alg.block_len >= digest_alg.output_len); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>ctx = hmac::Context::with_key(<span class="kw-2">&</span>prk.<span class="number">0</span>); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>n = <span class="number">1u8</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>out = out; |
| <span class="kw">loop </span>{ |
| <span class="kw">for </span>info <span class="kw">in </span>info { |
| ctx.update(info); |
| } |
| ctx.update(<span class="kw-2">&</span>[n]); |
| |
| <span class="kw">let </span>t = ctx.sign(); |
| <span class="kw">let </span>t = t.as_ref(); |
| |
| <span class="comment">// Append `t` to the output. |
| </span>out = <span class="kw">if </span>out.len() < digest_alg.output_len { |
| <span class="kw">let </span>len = out.len(); |
| out.copy_from_slice(<span class="kw-2">&</span>t[..len]); |
| <span class="kw-2">&mut </span>[] |
| } <span class="kw">else </span>{ |
| <span class="kw">let </span>(this_chunk, rest) = out.split_at_mut(digest_alg.output_len); |
| this_chunk.copy_from_slice(t); |
| rest |
| }; |
| |
| <span class="kw">if </span>out.is_empty() { |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(()); |
| } |
| |
| ctx = hmac::Context::with_key(<span class="kw-2">&</span>prk.<span class="number">0</span>); |
| ctx.update(t); |
| n = n.checked_add(<span class="number">1</span>).unwrap(); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="ring" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
