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</pre><pre class="rust ">
<span class="comment">// Copyright 2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class="comment">// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="doccomment">//! The ChaCha random number generator.</span>
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">num</span>::<span class="ident">Wrapping</span> <span class="kw">as</span> <span class="ident">w</span>;
<span class="kw">use</span> {<span class="ident">Rng</span>, <span class="ident">SeedableRng</span>, <span class="ident">Rand</span>};
<span class="attribute">#[<span class="ident">allow</span>(<span class="ident">bad_style</span>)]</span>
<span class="kw">type</span> <span class="ident">w32</span> <span class="op">=</span> <span class="ident">w</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span>;
<span class="kw">const</span> <span class="ident">KEY_WORDS</span> : <span class="ident">usize</span> <span class="op">=</span> <span class="number">8</span>; <span class="comment">// 8 words for the 256-bit key</span>
<span class="kw">const</span> <span class="ident">STATE_WORDS</span> : <span class="ident">usize</span> <span class="op">=</span> <span class="number">16</span>;
<span class="kw">const</span> <span class="ident">CHACHA_ROUNDS</span>: <span class="ident">u32</span> <span class="op">=</span> <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].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The ChaCha algorithm is widely accepted as suitable for</span>
<span class="doccomment">/// cryptographic purposes, but this implementation has not been</span>
<span class="doccomment">/// verified as such. Prefer a generator like `OsRng` that defers to</span>
<span class="doccomment">/// the operating system for cases that need high security.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [1]: D. J. Bernstein, [*ChaCha, a variant of</span>
<span class="doccomment">/// Salsa20*](http://cr.yp.to/chacha.html)</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">ChaChaRng</span> {
<span class="ident">buffer</span>: [<span class="ident">w32</span>; <span class="ident">STATE_WORDS</span>], <span class="comment">// Internal buffer of output</span>
<span class="ident">state</span>: [<span class="ident">w32</span>; <span class="ident">STATE_WORDS</span>], <span class="comment">// Initial state</span>
<span class="ident">index</span>: <span class="ident">usize</span>, <span class="comment">// Index into state</span>
}
<span class="kw">static</span> <span class="ident">EMPTY</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">ChaChaRng</span> {
<span class="ident">buffer</span>: [<span class="ident">w</span>(<span class="number">0</span>); <span class="ident">STATE_WORDS</span>],
<span class="ident">state</span>: [<span class="ident">w</span>(<span class="number">0</span>); <span class="ident">STATE_WORDS</span>],
<span class="ident">index</span>: <span class="ident">STATE_WORDS</span>
};
<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">quarter_round</span>{
(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span>: <span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>: <span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span>: <span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span>: <span class="ident">expr</span>) <span class="op">=></span> {{
<span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span> <span class="op">+</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span> <span class="op">^</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span> <span class="op">=</span> <span class="ident">w</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span>.<span class="number">0</span>.<span class="ident">rotate_left</span>(<span class="number">16</span>));
<span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span> <span class="op">+</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span> <span class="op">^</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span> <span class="op">=</span> <span class="ident">w</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>.<span class="number">0</span>.<span class="ident">rotate_left</span>(<span class="number">12</span>));
<span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span> <span class="op">+</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span> <span class="op">^</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span> <span class="op">=</span> <span class="ident">w</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span>.<span class="number">0</span>.<span class="ident">rotate_left</span>( <span class="number">8</span>));
<span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span> <span class="op">+</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">d</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span> <span class="op">^</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">c</span>; <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span> <span class="op">=</span> <span class="ident">w</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>.<span class="number">0</span>.<span class="ident">rotate_left</span>( <span class="number">7</span>));
}}
}
<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">double_round</span>{
(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>: <span class="ident">expr</span>) <span class="op">=></span> {{
<span class="comment">// Column round</span>
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">0</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">4</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">8</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">12</span>]);
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">1</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">5</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">9</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">13</span>]);
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">2</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">6</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">10</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">14</span>]);
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">3</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">7</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">11</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">15</span>]);
<span class="comment">// Diagonal round</span>
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">0</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">5</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">10</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">15</span>]);
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">1</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">6</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">11</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">12</span>]);
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">2</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">7</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">8</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">13</span>]);
<span class="macro">quarter_round</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">3</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">4</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[ <span class="number">9</span>], <span class="macro-nonterminal">$</span><span class="macro-nonterminal">x</span>[<span class="number">14</span>]);
}}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">core</span>(<span class="ident">output</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">w32</span>; <span class="ident">STATE_WORDS</span>], <span class="ident">input</span>: <span class="kw-2">&</span>[<span class="ident">w32</span>; <span class="ident">STATE_WORDS</span>]) {
<span class="kw-2">*</span><span class="ident">output</span> <span class="op">=</span> <span class="kw-2">*</span><span class="ident">input</span>;
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="ident">CHACHA_ROUNDS</span> <span class="op">/</span> <span class="number">2</span> {
<span class="macro">double_round</span><span class="macro">!</span>(<span class="ident">output</span>);
}
<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">STATE_WORDS</span> {
<span class="ident">output</span>[<span class="ident">i</span>] <span class="op">=</span> <span class="ident">output</span>[<span class="ident">i</span>] <span class="op">+</span> <span class="ident">input</span>[<span class="ident">i</span>];
}
}
<span class="kw">impl</span> <span class="ident">ChaChaRng</span> {
<span class="doccomment">/// Create an ChaCha random number generator using the default</span>
<span class="doccomment">/// fixed key of 8 zero words.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// use rand::{Rng, ChaChaRng};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut ra = ChaChaRng::new_unseeded();</span>
<span class="doccomment">/// println!("{:?}", ra.next_u32());</span>
<span class="doccomment">/// println!("{:?}", ra.next_u32());</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Since this equivalent to a RNG with a fixed seed, repeated executions</span>
<span class="doccomment">/// of an unseeded RNG will produce the same result. This code sample will</span>
<span class="doccomment">/// consistently produce:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// - 2917185654</span>
<span class="doccomment">/// - 2419978656</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new_unseeded</span>() <span class="op">-></span> <span class="ident">ChaChaRng</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">EMPTY</span>;
<span class="ident">rng</span>.<span class="ident">init</span>(<span class="kw-2">&</span>[<span class="number">0</span>; <span class="ident">KEY_WORDS</span>]);
<span class="ident">rng</span>
}
<span class="doccomment">/// Sets the internal 128-bit ChaCha counter to</span>
<span class="doccomment">/// a user-provided value. This permits jumping</span>
<span class="doccomment">/// arbitrarily ahead (or backwards) in the pseudorandom stream.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Since the nonce words are used to extend the counter to 128 bits,</span>
<span class="doccomment">/// users wishing to obtain the conventional ChaCha pseudorandom stream</span>
<span class="doccomment">/// associated with a particular nonce can call this function with</span>
<span class="doccomment">/// arguments `0, desired_nonce`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```rust</span>
<span class="doccomment">/// use rand::{Rng, ChaChaRng};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut ra = ChaChaRng::new_unseeded();</span>
<span class="doccomment">/// ra.set_counter(0u64, 1234567890u64);</span>
<span class="doccomment">/// println!("{:?}", ra.next_u32());</span>
<span class="doccomment">/// println!("{:?}", ra.next_u32());</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">set_counter</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">counter_low</span>: <span class="ident">u64</span>, <span class="ident">counter_high</span>: <span class="ident">u64</span>) {
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">12</span>] <span class="op">=</span> <span class="ident">w</span>((<span class="ident">counter_low</span> <span class="op">>></span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u32</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">13</span>] <span class="op">=</span> <span class="ident">w</span>((<span class="ident">counter_low</span> <span class="op">>></span> <span class="number">32</span>) <span class="kw">as</span> <span class="ident">u32</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">14</span>] <span class="op">=</span> <span class="ident">w</span>((<span class="ident">counter_high</span> <span class="op">>></span> <span class="number">0</span>) <span class="kw">as</span> <span class="ident">u32</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">15</span>] <span class="op">=</span> <span class="ident">w</span>((<span class="ident">counter_high</span> <span class="op">>></span> <span class="number">32</span>) <span class="kw">as</span> <span class="ident">u32</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="ident">STATE_WORDS</span>; <span class="comment">// force recomputation</span>
}
<span class="doccomment">/// Initializes `self.state` with the appropriate key and constants</span>
<span class="doccomment">///</span>
<span class="doccomment">/// We deviate slightly from the ChaCha specification regarding</span>
<span class="doccomment">/// the nonce, which is used to extend the counter to 128 bits.</span>
<span class="doccomment">/// This is provably as strong as the original cipher, though,</span>
<span class="doccomment">/// since any distinguishing attack on our variant also works</span>
<span class="doccomment">/// against ChaCha with a chosen-nonce. See the XSalsa20 [1]</span>
<span class="doccomment">/// security proof for a more involved example of this.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The modified word layout is:</span>
<span class="doccomment">/// ```text</span>
<span class="doccomment">/// constant constant constant constant</span>
<span class="doccomment">/// key key key key</span>
<span class="doccomment">/// key key key key</span>
<span class="doccomment">/// counter counter counter counter</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// [1]: Daniel J. Bernstein. [*Extending the Salsa20</span>
<span class="doccomment">/// nonce.*](http://cr.yp.to/papers.html#xsalsa)</span>
<span class="kw">fn</span> <span class="ident">init</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">key</span>: <span class="kw-2">&</span>[<span class="ident">u32</span>; <span class="ident">KEY_WORDS</span>]) {
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">0</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0x61707865</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">1</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0x3320646E</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">2</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0x79622D32</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">3</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0x6B206574</span>);
<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">KEY_WORDS</span> {
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">4</span><span class="op">+</span><span class="ident">i</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="ident">key</span>[<span class="ident">i</span>]);
}
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">12</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">13</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">14</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0</span>);
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">15</span>] <span class="op">=</span> <span class="ident">w</span>(<span class="number">0</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="ident">STATE_WORDS</span>;
}
<span class="doccomment">/// Refill the internal output buffer (`self.buffer`)</span>
<span class="kw">fn</span> <span class="ident">update</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="ident">core</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">buffer</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">state</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// update 128-bit counter</span>
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">12</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">12</span>] <span class="op">+</span> <span class="ident">w</span>(<span class="number">1</span>);
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">12</span>] <span class="op">!=</span> <span class="ident">w</span>(<span class="number">0</span>) { <span class="kw">return</span> };
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">13</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">13</span>] <span class="op">+</span> <span class="ident">w</span>(<span class="number">1</span>);
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">13</span>] <span class="op">!=</span> <span class="ident">w</span>(<span class="number">0</span>) { <span class="kw">return</span> };
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">14</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">14</span>] <span class="op">+</span> <span class="ident">w</span>(<span class="number">1</span>);
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">14</span>] <span class="op">!=</span> <span class="ident">w</span>(<span class="number">0</span>) { <span class="kw">return</span> };
<span class="self">self</span>.<span class="ident">state</span>[<span class="number">15</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">15</span>] <span class="op">+</span> <span class="ident">w</span>(<span class="number">1</span>);
}
}
<span class="kw">impl</span> <span class="ident">Rng</span> <span class="kw">for</span> <span class="ident">ChaChaRng</span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">next_u32</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">u32</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op">==</span> <span class="ident">STATE_WORDS</span> {
<span class="self">self</span>.<span class="ident">update</span>();
}
<span class="kw">let</span> <span class="ident">value</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">buffer</span>[<span class="self">self</span>.<span class="ident">index</span> <span class="op">%</span> <span class="ident">STATE_WORDS</span>];
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="ident">value</span>.<span class="number">0</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">SeedableRng</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u32</span>]<span class="op">></span> <span class="kw">for</span> <span class="ident">ChaChaRng</span> {
<span class="kw">fn</span> <span class="ident">reseed</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">seed</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u32</span>]) {
<span class="comment">// reset state</span>
<span class="self">self</span>.<span class="ident">init</span>(<span class="kw-2">&</span>[<span class="number">0u32</span>; <span class="ident">KEY_WORDS</span>]);
<span class="comment">// set key in place</span>
<span class="kw">let</span> <span class="ident">key</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">state</span>[<span class="number">4</span> .. <span class="number">4</span><span class="op">+</span><span class="ident">KEY_WORDS</span>];
<span class="kw">for</span> (<span class="ident">k</span>, <span class="ident">s</span>) <span class="kw">in</span> <span class="ident">key</span>.<span class="ident">iter_mut</span>().<span class="ident">zip</span>(<span class="ident">seed</span>.<span class="ident">iter</span>()) {
<span class="kw-2">*</span><span class="ident">k</span> <span class="op">=</span> <span class="ident">w</span>(<span class="kw-2">*</span><span class="ident">s</span>);
}
}
<span class="doccomment">/// Create a ChaCha generator from a seed,</span>
<span class="doccomment">/// obtained from a variable-length u32 array.</span>
<span class="doccomment">/// Only up to 8 words are used; if less than 8</span>
<span class="doccomment">/// words are used, the remaining are set to zero.</span>
<span class="kw">fn</span> <span class="ident">from_seed</span>(<span class="ident">seed</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u32</span>]) <span class="op">-></span> <span class="ident">ChaChaRng</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">EMPTY</span>;
<span class="ident">rng</span>.<span class="ident">reseed</span>(<span class="ident">seed</span>);
<span class="ident">rng</span>
}
}
<span class="kw">impl</span> <span class="ident">Rand</span> <span class="kw">for</span> <span class="ident">ChaChaRng</span> {
<span class="kw">fn</span> <span class="ident">rand</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Rng</span><span class="op">></span>(<span class="ident">other</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">R</span>) <span class="op">-></span> <span class="ident">ChaChaRng</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">key</span> : [<span class="ident">u32</span>; <span class="ident">KEY_WORDS</span>] <span class="op">=</span> [<span class="number">0</span>; <span class="ident">KEY_WORDS</span>];
<span class="kw">for</span> <span class="ident">word</span> <span class="kw">in</span> <span class="ident">key</span>.<span class="ident">iter_mut</span>() {
<span class="kw-2">*</span><span class="ident">word</span> <span class="op">=</span> <span class="ident">other</span>.<span class="ident">gen</span>();
}
<span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="kw-2">&</span><span class="ident">key</span>[..])
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">mod</span> <span class="ident">test</span> {
<span class="kw">use</span> {<span class="ident">Rng</span>, <span class="ident">SeedableRng</span>};
<span class="kw">use</span> <span class="kw">super</span>::<span class="ident">ChaChaRng</span>;
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_rng_rand_seeded</span>() {
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> ::<span class="ident">test</span>::<span class="ident">rng</span>().<span class="ident">gen_iter</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>().<span class="ident">take</span>(<span class="number">8</span>).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">>></span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ra</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="kw-2">&</span><span class="ident">s</span>[..]);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rb</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="kw-2">&</span><span class="ident">s</span>[..]);
<span class="macro">assert</span><span class="macro">!</span>(::<span class="ident">test</span>::<span class="ident">iter_eq</span>(<span class="ident">ra</span>.<span class="ident">gen_ascii_chars</span>().<span class="ident">take</span>(<span class="number">100</span>),
<span class="ident">rb</span>.<span class="ident">gen_ascii_chars</span>().<span class="ident">take</span>(<span class="number">100</span>)));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_rng_seeded</span>() {
<span class="kw">let</span> <span class="ident">seed</span> : <span class="kw-2">&</span>[_] <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">0</span>,<span class="number">1</span>,<span class="number">2</span>,<span class="number">3</span>,<span class="number">4</span>,<span class="number">5</span>,<span class="number">6</span>,<span class="number">7</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ra</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rb</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>);
<span class="macro">assert</span><span class="macro">!</span>(::<span class="ident">test</span>::<span class="ident">iter_eq</span>(<span class="ident">ra</span>.<span class="ident">gen_ascii_chars</span>().<span class="ident">take</span>(<span class="number">100</span>),
<span class="ident">rb</span>.<span class="ident">gen_ascii_chars</span>().<span class="ident">take</span>(<span class="number">100</span>)));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_rng_reseed</span>() {
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> ::<span class="ident">test</span>::<span class="ident">rng</span>().<span class="ident">gen_iter</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>().<span class="ident">take</span>(<span class="number">8</span>).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">>></span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">r</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="kw-2">&</span><span class="ident">s</span>[..]);
<span class="kw">let</span> <span class="ident">string1</span>: <span class="ident">String</span> <span class="op">=</span> <span class="ident">r</span>.<span class="ident">gen_ascii_chars</span>().<span class="ident">take</span>(<span class="number">100</span>).<span class="ident">collect</span>();
<span class="ident">r</span>.<span class="ident">reseed</span>(<span class="kw-2">&</span><span class="ident">s</span>);
<span class="kw">let</span> <span class="ident">string2</span>: <span class="ident">String</span> <span class="op">=</span> <span class="ident">r</span>.<span class="ident">gen_ascii_chars</span>().<span class="ident">take</span>(<span class="number">100</span>).<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">string1</span>, <span class="ident">string2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_rng_true_values</span>() {
<span class="comment">// Test vectors 1 and 2 from</span>
<span class="comment">// http://tools.ietf.org/html/draft-nir-cfrg-chacha20-poly1305-04</span>
<span class="kw">let</span> <span class="ident">seed</span> : <span class="kw-2">&</span>[_] <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">0u32</span>; <span class="number">8</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ra</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>);
<span class="kw">let</span> <span class="ident">v</span> <span class="op">=</span> (<span class="number">0</span>..<span class="number">16</span>).<span class="ident">map</span>(<span class="op">|</span>_<span class="op">|</span> <span class="ident">ra</span>.<span class="ident">next_u32</span>()).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">>></span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>,
<span class="macro">vec</span><span class="macro">!</span>(<span class="number">0xade0b876</span>, <span class="number">0x903df1a0</span>, <span class="number">0xe56a5d40</span>, <span class="number">0x28bd8653</span>,
<span class="number">0xb819d2bd</span>, <span class="number">0x1aed8da0</span>, <span class="number">0xccef36a8</span>, <span class="number">0xc70d778b</span>,
<span class="number">0x7c5941da</span>, <span class="number">0x8d485751</span>, <span class="number">0x3fe02477</span>, <span class="number">0x374ad8b8</span>,
<span class="number">0xf4b8436a</span>, <span class="number">0x1ca11815</span>, <span class="number">0x69b687c3</span>, <span class="number">0x8665eeb2</span>));
<span class="kw">let</span> <span class="ident">v</span> <span class="op">=</span> (<span class="number">0</span>..<span class="number">16</span>).<span class="ident">map</span>(<span class="op">|</span>_<span class="op">|</span> <span class="ident">ra</span>.<span class="ident">next_u32</span>()).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">>></span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>,
<span class="macro">vec</span><span class="macro">!</span>(<span class="number">0xbee7079f</span>, <span class="number">0x7a385155</span>, <span class="number">0x7c97ba98</span>, <span class="number">0x0d082d73</span>,
<span class="number">0xa0290fcb</span>, <span class="number">0x6965e348</span>, <span class="number">0x3e53c612</span>, <span class="number">0xed7aee32</span>,
<span class="number">0x7621b729</span>, <span class="number">0x434ee69c</span>, <span class="number">0xb03371d5</span>, <span class="number">0xd539d874</span>,
<span class="number">0x281fed31</span>, <span class="number">0x45fb0a51</span>, <span class="number">0x1f0ae1ac</span>, <span class="number">0x6f4d794b</span>));
<span class="kw">let</span> <span class="ident">seed</span> : <span class="kw-2">&</span>[_] <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">0</span>,<span class="number">1</span>,<span class="number">2</span>,<span class="number">3</span>,<span class="number">4</span>,<span class="number">5</span>,<span class="number">6</span>,<span class="number">7</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ra</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>);
<span class="comment">// Store the 17*i-th 32-bit word,</span>
<span class="comment">// i.e., the i-th word of the i-th 16-word block</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">v</span> : <span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">new</span>();
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="number">16</span> {
<span class="ident">v</span>.<span class="ident">push</span>(<span class="ident">ra</span>.<span class="ident">next_u32</span>());
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="number">16</span> {
<span class="ident">ra</span>.<span class="ident">next_u32</span>();
}
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>,
<span class="macro">vec</span><span class="macro">!</span>(<span class="number">0xf225c81a</span>, <span class="number">0x6ab1be57</span>, <span class="number">0x04d42951</span>, <span class="number">0x70858036</span>,
<span class="number">0x49884684</span>, <span class="number">0x64efec72</span>, <span class="number">0x4be2d186</span>, <span class="number">0x3615b384</span>,
<span class="number">0x11cfa18e</span>, <span class="number">0xd3c50049</span>, <span class="number">0x75c775f6</span>, <span class="number">0x434c6530</span>,
<span class="number">0x2c5bad8f</span>, <span class="number">0x898881dc</span>, <span class="number">0x5f1c86d9</span>, <span class="number">0xc1f8e7f4</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_rng_clone</span>() {
<span class="kw">let</span> <span class="ident">seed</span> : <span class="kw-2">&</span>[_] <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">0u32</span>; <span class="number">8</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span>: <span class="ident">ChaChaRng</span> <span class="op">=</span> <span class="ident">SeedableRng</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">clone</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">clone</span>();
<span class="kw">for</span> _ <span class="kw">in</span> <span class="number">0</span>..<span class="number">16</span> {
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">rng</span>.<span class="ident">next_u64</span>(), <span class="ident">clone</span>.<span class="ident">next_u64</span>());
}
}
}
</pre>
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