| <!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/sunhe/incubator-teaclave/third_party/rust-sgx-sdk/sgx_rand/src/chacha.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>chacha.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="../../sgx_rand/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="../../sgx_rand/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">// Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License.. |
| |
| </span><span class="doccomment">//! The ChaCha random number generator. |
| |
| </span><span class="kw">use crate</span>::{w32, Rand, Rng, SeedableRng}; |
| <span class="kw">use </span>std::num::Wrapping <span class="kw">as </span>w; |
| |
| <span class="kw">const </span>KEY_WORDS: usize = <span class="number">8</span>; <span class="comment">// 8 words for the 256-bit key |
| </span><span class="kw">const </span>STATE_WORDS: usize = <span class="number">16</span>; |
| <span class="kw">const </span>CHACHA_ROUNDS: u32 = <span class="number">20</span>; <span class="comment">// Cryptographically secure from 8 upwards as of this writing |
| |
| </span><span class="doccomment">/// A random number generator that uses the ChaCha20 algorithm \[1\]. |
| /// |
| /// The ChaCha algorithm is widely accepted as suitable for |
| /// cryptographic purposes, but this implementation has not been |
| /// verified as such. Prefer a generator like `OsRng` that defers to |
| /// the operating system for cases that need high security. |
| /// |
| /// \[1\]: D. J. Bernstein, [*ChaCha, a variant of |
| /// Salsa20*](http://cr.yp.to/chacha.html) |
| </span><span class="attribute">#[derive(Copy, Clone, Debug)] |
| </span><span class="kw">pub struct </span>ChaChaRng { |
| buffer: [w32; STATE_WORDS], <span class="comment">// Internal buffer of output |
| </span>state: [w32; STATE_WORDS], <span class="comment">// Initial state |
| </span>index: usize, <span class="comment">// Index into state |
| </span>} |
| |
| <span class="kw">static </span>EMPTY: ChaChaRng = ChaChaRng { |
| buffer: [w(<span class="number">0</span>); STATE_WORDS], |
| state: [w(<span class="number">0</span>); STATE_WORDS], |
| index: STATE_WORDS, |
| }; |
| |
| <span class="macro">macro_rules! </span>quarter_round { |
| (<span class="macro-nonterminal">$a</span>: expr, <span class="macro-nonterminal">$b</span>: expr, <span class="macro-nonterminal">$c</span>: expr, <span class="macro-nonterminal">$d</span>: expr) => {{ |
| <span class="macro-nonterminal">$a </span>+= <span class="macro-nonterminal">$b</span>; |
| <span class="macro-nonterminal">$d </span>^= <span class="macro-nonterminal">$a</span>; |
| <span class="macro-nonterminal">$d </span>= w(<span class="macro-nonterminal">$d</span>.<span class="number">0</span>.rotate_left(<span class="number">16</span>)); |
| <span class="macro-nonterminal">$c </span>+= <span class="macro-nonterminal">$d</span>; |
| <span class="macro-nonterminal">$b </span>^= <span class="macro-nonterminal">$c</span>; |
| <span class="macro-nonterminal">$b </span>= w(<span class="macro-nonterminal">$b</span>.<span class="number">0</span>.rotate_left(<span class="number">12</span>)); |
| <span class="macro-nonterminal">$a </span>+= <span class="macro-nonterminal">$b</span>; |
| <span class="macro-nonterminal">$d </span>^= <span class="macro-nonterminal">$a</span>; |
| <span class="macro-nonterminal">$d </span>= w(<span class="macro-nonterminal">$d</span>.<span class="number">0</span>.rotate_left(<span class="number">8</span>)); |
| <span class="macro-nonterminal">$c </span>+= <span class="macro-nonterminal">$d</span>; |
| <span class="macro-nonterminal">$b </span>^= <span class="macro-nonterminal">$c</span>; |
| <span class="macro-nonterminal">$b </span>= w(<span class="macro-nonterminal">$b</span>.<span class="number">0</span>.rotate_left(<span class="number">7</span>)); |
| }}; |
| } |
| |
| <span class="macro">macro_rules! </span>double_round { |
| (<span class="macro-nonterminal">$x</span>: expr) => {{ |
| <span class="comment">// Column round |
| </span><span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">0</span>], <span class="macro-nonterminal">$x</span>[<span class="number">4</span>], <span class="macro-nonterminal">$x</span>[<span class="number">8</span>], <span class="macro-nonterminal">$x</span>[<span class="number">12</span>]); |
| <span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">1</span>], <span class="macro-nonterminal">$x</span>[<span class="number">5</span>], <span class="macro-nonterminal">$x</span>[<span class="number">9</span>], <span class="macro-nonterminal">$x</span>[<span class="number">13</span>]); |
| <span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">2</span>], <span class="macro-nonterminal">$x</span>[<span class="number">6</span>], <span class="macro-nonterminal">$x</span>[<span class="number">10</span>], <span class="macro-nonterminal">$x</span>[<span class="number">14</span>]); |
| <span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">3</span>], <span class="macro-nonterminal">$x</span>[<span class="number">7</span>], <span class="macro-nonterminal">$x</span>[<span class="number">11</span>], <span class="macro-nonterminal">$x</span>[<span class="number">15</span>]); |
| <span class="comment">// Diagonal round |
| </span><span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">0</span>], <span class="macro-nonterminal">$x</span>[<span class="number">5</span>], <span class="macro-nonterminal">$x</span>[<span class="number">10</span>], <span class="macro-nonterminal">$x</span>[<span class="number">15</span>]); |
| <span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">1</span>], <span class="macro-nonterminal">$x</span>[<span class="number">6</span>], <span class="macro-nonterminal">$x</span>[<span class="number">11</span>], <span class="macro-nonterminal">$x</span>[<span class="number">12</span>]); |
| <span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">2</span>], <span class="macro-nonterminal">$x</span>[<span class="number">7</span>], <span class="macro-nonterminal">$x</span>[<span class="number">8</span>], <span class="macro-nonterminal">$x</span>[<span class="number">13</span>]); |
| <span class="macro">quarter_round!</span>(<span class="macro-nonterminal">$x</span>[<span class="number">3</span>], <span class="macro-nonterminal">$x</span>[<span class="number">4</span>], <span class="macro-nonterminal">$x</span>[<span class="number">9</span>], <span class="macro-nonterminal">$x</span>[<span class="number">14</span>]); |
| }}; |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>core(output: <span class="kw-2">&mut </span>[w32; STATE_WORDS], input: <span class="kw-2">&</span>[w32; STATE_WORDS]) { |
| <span class="kw-2">*</span>output = <span class="kw-2">*</span>input; |
| |
| <span class="kw">for _ in </span><span class="number">0</span>..CHACHA_ROUNDS / <span class="number">2 </span>{ |
| <span class="macro">double_round!</span>(output); |
| } |
| |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..STATE_WORDS { |
| output[i] += input[i]; |
| } |
| } |
| |
| <span class="kw">impl </span>ChaChaRng { |
| <span class="doccomment">/// Create an ChaCha random number generator using the default |
| /// fixed key of 8 zero words. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// use sgx_rand::{Rng, ChaChaRng}; |
| /// |
| /// let mut ra = ChaChaRng::new_unseeded(); |
| /// println!("{:?}", ra.next_u32()); |
| /// println!("{:?}", ra.next_u32()); |
| /// ``` |
| /// |
| /// Since this equivalent to a RNG with a fixed seed, repeated executions |
| /// of an unseeded RNG will produce the same result. This code sample will |
| /// consistently produce: |
| /// |
| /// - 2917185654 |
| /// - 2419978656 |
| </span><span class="kw">pub fn </span>new_unseeded() -> ChaChaRng { |
| <span class="kw">let </span><span class="kw-2">mut </span>rng = EMPTY; |
| rng.init(<span class="kw-2">&</span>[<span class="number">0</span>; KEY_WORDS]); |
| rng |
| } |
| |
| <span class="doccomment">/// Sets the internal 128-bit ChaCha counter to |
| /// a user-provided value. This permits jumping |
| /// arbitrarily ahead (or backwards) in the pseudorandom stream. |
| /// |
| /// Since the nonce words are used to extend the counter to 128 bits, |
| /// users wishing to obtain the conventional ChaCha pseudorandom stream |
| /// associated with a particular nonce can call this function with |
| /// arguments `0, desired_nonce`. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// use sgx_rand::{Rng, ChaChaRng}; |
| /// |
| /// let mut ra = ChaChaRng::new_unseeded(); |
| /// ra.set_counter(0u64, 1234567890u64); |
| /// println!("{:?}", ra.next_u32()); |
| /// println!("{:?}", ra.next_u32()); |
| /// ``` |
| </span><span class="attribute">#[allow(clippy::identity_op)] |
| </span><span class="kw">pub fn </span>set_counter(<span class="kw-2">&mut </span><span class="self">self</span>, counter_low: u64, counter_high: u64) { |
| <span class="self">self</span>.state[<span class="number">12</span>] = w((counter_low >> <span class="number">0</span>) <span class="kw">as </span>u32); |
| <span class="self">self</span>.state[<span class="number">13</span>] = w((counter_low >> <span class="number">32</span>) <span class="kw">as </span>u32); |
| <span class="self">self</span>.state[<span class="number">14</span>] = w((counter_high >> <span class="number">0</span>) <span class="kw">as </span>u32); |
| <span class="self">self</span>.state[<span class="number">15</span>] = w((counter_high >> <span class="number">32</span>) <span class="kw">as </span>u32); |
| <span class="self">self</span>.index = STATE_WORDS; <span class="comment">// force recomputation |
| </span>} |
| |
| <span class="doccomment">/// Initializes `self.state` with the appropriate key and constants |
| /// |
| /// We deviate slightly from the ChaCha specification regarding |
| /// the nonce, which is used to extend the counter to 128 bits. |
| /// This is provably as strong as the original cipher, though, |
| /// since any distinguishing attack on our variant also works |
| /// against ChaCha with a chosen-nonce. See the XSalsa20 [1] |
| /// security proof for a more involved example of this. |
| /// |
| /// The modified word layout is: |
| /// ```text |
| /// constant constant constant constant |
| /// key key key key |
| /// key key key key |
| /// counter counter counter counter |
| /// ``` |
| /// [1]: Daniel J. Bernstein. [*Extending the Salsa20 |
| /// nonce.*](http://cr.yp.to/papers.html#xsalsa) |
| </span><span class="kw">fn </span>init(<span class="kw-2">&mut </span><span class="self">self</span>, key: <span class="kw-2">&</span>[u32; KEY_WORDS]) { |
| <span class="self">self</span>.state[<span class="number">0</span>] = w(<span class="number">0x61707865</span>); |
| <span class="self">self</span>.state[<span class="number">1</span>] = w(<span class="number">0x3320646E</span>); |
| <span class="self">self</span>.state[<span class="number">2</span>] = w(<span class="number">0x79622D32</span>); |
| <span class="self">self</span>.state[<span class="number">3</span>] = w(<span class="number">0x6B206574</span>); |
| |
| <span class="kw">for </span>(i, <span class="kw-2">&</span>k) <span class="kw">in </span>key.iter().enumerate().take(KEY_WORDS) { |
| <span class="self">self</span>.state[<span class="number">4 </span>+ i] = w(k); |
| } |
| |
| <span class="self">self</span>.state[<span class="number">12</span>] = w(<span class="number">0</span>); |
| <span class="self">self</span>.state[<span class="number">13</span>] = w(<span class="number">0</span>); |
| <span class="self">self</span>.state[<span class="number">14</span>] = w(<span class="number">0</span>); |
| <span class="self">self</span>.state[<span class="number">15</span>] = w(<span class="number">0</span>); |
| |
| <span class="self">self</span>.index = STATE_WORDS; |
| } |
| |
| <span class="doccomment">/// Refill the internal output buffer (`self.buffer`) |
| </span><span class="kw">fn </span>update(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| core(<span class="kw-2">&mut </span><span class="self">self</span>.buffer, <span class="kw-2">&</span><span class="self">self</span>.state); |
| <span class="self">self</span>.index = <span class="number">0</span>; |
| <span class="comment">// update 128-bit counter |
| </span><span class="self">self</span>.state[<span class="number">12</span>] += w(<span class="number">1</span>); |
| <span class="kw">if </span><span class="self">self</span>.state[<span class="number">12</span>] != w(<span class="number">0</span>) { |
| <span class="kw">return</span>; |
| }; |
| <span class="self">self</span>.state[<span class="number">13</span>] += w(<span class="number">1</span>); |
| <span class="kw">if </span><span class="self">self</span>.state[<span class="number">13</span>] != w(<span class="number">0</span>) { |
| <span class="kw">return</span>; |
| }; |
| <span class="self">self</span>.state[<span class="number">14</span>] += w(<span class="number">1</span>); |
| <span class="kw">if </span><span class="self">self</span>.state[<span class="number">14</span>] != w(<span class="number">0</span>) { |
| <span class="kw">return</span>; |
| }; |
| <span class="self">self</span>.state[<span class="number">15</span>] += w(<span class="number">1</span>); |
| } |
| } |
| |
| <span class="kw">impl </span>Rng <span class="kw">for </span>ChaChaRng { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>next_u32(<span class="kw-2">&mut </span><span class="self">self</span>) -> u32 { |
| <span class="kw">if </span><span class="self">self</span>.index == STATE_WORDS { |
| <span class="self">self</span>.update(); |
| } |
| |
| <span class="kw">let </span>value = <span class="self">self</span>.buffer[<span class="self">self</span>.index % STATE_WORDS]; |
| <span class="self">self</span>.index += <span class="number">1</span>; |
| value.<span class="number">0 |
| </span>} |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> SeedableRng<<span class="kw-2">&</span><span class="lifetime">'a </span>[u32]> <span class="kw">for </span>ChaChaRng { |
| <span class="kw">fn </span>reseed(<span class="kw-2">&mut </span><span class="self">self</span>, seed: <span class="kw-2">&</span><span class="lifetime">'a </span>[u32]) { |
| <span class="comment">// reset state |
| </span><span class="self">self</span>.init(<span class="kw-2">&</span>[<span class="number">0u32</span>; KEY_WORDS]); |
| <span class="comment">// set key in place |
| </span><span class="kw">let </span>key = <span class="kw-2">&mut </span><span class="self">self</span>.state[<span class="number">4</span>..<span class="number">4 </span>+ KEY_WORDS]; |
| <span class="kw">for </span>(k, s) <span class="kw">in </span>key.iter_mut().zip(seed.iter()) { |
| <span class="kw-2">*</span>k = w(<span class="kw-2">*</span>s); |
| } |
| } |
| |
| <span class="doccomment">/// Create a ChaCha generator from a seed, |
| /// obtained from a variable-length u32 array. |
| /// Only up to 8 words are used; if less than 8 |
| /// words are used, the remaining are set to zero. |
| </span><span class="kw">fn </span>from_seed(seed: <span class="kw-2">&</span><span class="lifetime">'a </span>[u32]) -> ChaChaRng { |
| <span class="kw">let </span><span class="kw-2">mut </span>rng = EMPTY; |
| rng.reseed(seed); |
| rng |
| } |
| } |
| |
| <span class="kw">impl </span>Rand <span class="kw">for </span>ChaChaRng { |
| <span class="kw">fn </span>rand<R: Rng>(other: <span class="kw-2">&mut </span>R) -> ChaChaRng { |
| <span class="kw">let </span><span class="kw-2">mut </span>key: [u32; KEY_WORDS] = [<span class="number">0</span>; KEY_WORDS]; |
| <span class="kw">for </span>word <span class="kw">in </span>key.iter_mut() { |
| <span class="kw-2">*</span>word = other.gen(); |
| } |
| SeedableRng::from_seed(<span class="kw-2">&</span>key[..]) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="sgx_rand" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
