| <!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/registry/src/github.com-1ecc6299db9ec823/ring-0.16.20/src/limb.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>limb.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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| <span id="603">603</span> |
| <span id="604">604</span> |
| </pre><pre class="rust"><code><span class="comment">// Copyright 2016 David Judd. |
| // Copyright 2016 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">//! Unsigned multi-precision integer arithmetic. |
| //! |
| //! Limbs ordered least-significant-limb to most-significant-limb. The bits |
| //! limbs use the native endianness. |
| |
| </span><span class="kw">use crate</span>::{c, error}; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">use </span><span class="kw">crate</span>::bits; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">use </span>core::num::Wrapping; |
| |
| <span class="comment">// XXX: Not correct for x32 ABIs. |
| </span><span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| </span><span class="kw">pub type </span>Limb = u64; |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"32"</span>)] |
| </span><span class="kw">pub type </span>Limb = u32; |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| </span><span class="kw">pub const </span>LIMB_BITS: usize = <span class="number">64</span>; |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"32"</span>)] |
| </span><span class="kw">pub const </span>LIMB_BITS: usize = <span class="number">32</span>; |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| #[derive(Debug, PartialEq)] |
| #[repr(u64)] |
| </span><span class="kw">pub enum </span>LimbMask { |
| True = <span class="number">0xffff_ffff_ffff_ffff</span>, |
| False = <span class="number">0</span>, |
| } |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"32"</span>)] |
| #[derive(Debug, PartialEq)] |
| #[repr(u32)] |
| </span><span class="kw">pub enum </span>LimbMask { |
| True = <span class="number">0xffff_ffff</span>, |
| False = <span class="number">0</span>, |
| } |
| |
| <span class="kw">pub const </span>LIMB_BYTES: usize = (LIMB_BITS + <span class="number">7</span>) / <span class="number">8</span>; |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>limbs_equal_limbs_consttime(a: <span class="kw-2">&</span>[Limb], b: <span class="kw-2">&</span>[Limb]) -> LimbMask { |
| <span class="kw">extern </span><span class="string">"C" </span>{ |
| <span class="kw">fn </span>LIMBS_equal(a: <span class="kw-2">*const </span>Limb, b: <span class="kw-2">*const </span>Limb, num_limbs: c::size_t) -> LimbMask; |
| } |
| |
| <span class="macro">assert_eq!</span>(a.len(), b.len()); |
| <span class="kw">unsafe </span>{ LIMBS_equal(a.as_ptr(), b.as_ptr(), a.len()) } |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>limbs_less_than_limbs_consttime(a: <span class="kw-2">&</span>[Limb], b: <span class="kw-2">&</span>[Limb]) -> LimbMask { |
| <span class="macro">assert_eq!</span>(a.len(), b.len()); |
| <span class="kw">unsafe </span>{ LIMBS_less_than(a.as_ptr(), b.as_ptr(), b.len()) } |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>limbs_less_than_limbs_vartime(a: <span class="kw-2">&</span>[Limb], b: <span class="kw-2">&</span>[Limb]) -> bool { |
| limbs_less_than_limbs_consttime(a, b) == LimbMask::True |
| } |
| |
| <span class="attribute">#[inline] |
| #[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">pub fn </span>limbs_less_than_limb_constant_time(a: <span class="kw-2">&</span>[Limb], b: Limb) -> LimbMask { |
| <span class="kw">unsafe </span>{ LIMBS_less_than_limb(a.as_ptr(), b, a.len()) } |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>limbs_are_zero_constant_time(limbs: <span class="kw-2">&</span>[Limb]) -> LimbMask { |
| <span class="kw">unsafe </span>{ LIMBS_are_zero(limbs.as_ptr(), limbs.len()) } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| #[inline] |
| </span><span class="kw">pub fn </span>limbs_are_even_constant_time(limbs: <span class="kw-2">&</span>[Limb]) -> LimbMask { |
| <span class="kw">unsafe </span>{ LIMBS_are_even(limbs.as_ptr(), limbs.len()) } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| #[inline] |
| </span><span class="kw">pub fn </span>limbs_equal_limb_constant_time(a: <span class="kw-2">&</span>[Limb], b: Limb) -> LimbMask { |
| <span class="kw">unsafe </span>{ LIMBS_equal_limb(a.as_ptr(), b, a.len()) } |
| } |
| |
| <span class="doccomment">/// Returns the number of bits in `a`. |
| </span><span class="comment">// |
| // This strives to be constant-time with respect to the values of all bits |
| // except the most significant bit. This does not attempt to be constant-time |
| // with respect to `a.len()` or the value of the result or the value of the |
| // most significant bit (It's 1, unless the input is zero, in which case it's |
| // zero.) |
| </span><span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">pub fn </span>limbs_minimal_bits(a: <span class="kw-2">&</span>[Limb]) -> bits::BitLength { |
| <span class="kw">for </span>num_limbs <span class="kw">in </span>(<span class="number">1</span>..=a.len()).rev() { |
| <span class="kw">let </span>high_limb = a[num_limbs - <span class="number">1</span>]; |
| |
| <span class="comment">// Find the number of set bits in |high_limb| by a linear scan from the |
| // most significant bit to the least significant bit. This works great |
| // for the most common inputs because usually the most significant bit |
| // it set. |
| </span><span class="kw">for </span>high_limb_num_bits <span class="kw">in </span>(<span class="number">1</span>..=LIMB_BITS).rev() { |
| <span class="kw">let </span>shifted = <span class="kw">unsafe </span>{ LIMB_shr(high_limb, high_limb_num_bits - <span class="number">1</span>) }; |
| <span class="kw">if </span>shifted != <span class="number">0 </span>{ |
| <span class="kw">return </span>bits::BitLength::from_usize_bits( |
| ((num_limbs - <span class="number">1</span>) * LIMB_BITS) + high_limb_num_bits, |
| ); |
| } |
| } |
| } |
| |
| <span class="comment">// No bits were set. |
| </span>bits::BitLength::from_usize_bits(<span class="number">0</span>) |
| } |
| |
| <span class="doccomment">/// Equivalent to `if (r >= m) { r -= m; }` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>limbs_reduce_once_constant_time(r: <span class="kw-2">&mut </span>[Limb], m: <span class="kw-2">&</span>[Limb]) { |
| <span class="macro">assert_eq!</span>(r.len(), m.len()); |
| <span class="kw">unsafe </span>{ LIMBS_reduce_once(r.as_mut_ptr(), m.as_ptr(), m.len()) }; |
| } |
| |
| <span class="attribute">#[derive(Clone, Copy, PartialEq)] |
| </span><span class="kw">pub enum </span>AllowZero { |
| No, |
| Yes, |
| } |
| |
| <span class="doccomment">/// Parses `input` into `result`, reducing it via conditional subtraction |
| /// (mod `m`). Assuming 2**((self.num_limbs * LIMB_BITS) - 1) < m and |
| /// m < 2**(self.num_limbs * LIMB_BITS), the value will be reduced mod `m` in |
| /// constant time so that the result is in the range [0, m) if `allow_zero` is |
| /// `AllowZero::Yes`, or [1, m) if `allow_zero` is `AllowZero::No`. `result` is |
| /// padded with zeros to its length. |
| </span><span class="kw">pub fn </span>parse_big_endian_in_range_partially_reduced_and_pad_consttime( |
| input: untrusted::Input, |
| allow_zero: AllowZero, |
| m: <span class="kw-2">&</span>[Limb], |
| result: <span class="kw-2">&mut </span>[Limb], |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| parse_big_endian_and_pad_consttime(input, result)<span class="question-mark">?</span>; |
| limbs_reduce_once_constant_time(result, m); |
| <span class="kw">if </span>allow_zero != AllowZero::Yes { |
| <span class="kw">if </span>limbs_are_zero_constant_time(<span class="kw-2">&</span>result) != LimbMask::False { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| } |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="doccomment">/// Parses `input` into `result`, verifies that the value is less than |
| /// `max_exclusive`, and pads `result` with zeros to its length. If `allow_zero` |
| /// is not `AllowZero::Yes`, zero values are rejected. |
| /// |
| /// This attempts to be constant-time with respect to the actual value *only if* |
| /// the value is actually in range. In other words, this won't leak anything |
| /// about a valid value, but it might leak small amounts of information about an |
| /// invalid value (which constraint it failed). |
| </span><span class="kw">pub fn </span>parse_big_endian_in_range_and_pad_consttime( |
| input: untrusted::Input, |
| allow_zero: AllowZero, |
| max_exclusive: <span class="kw-2">&</span>[Limb], |
| result: <span class="kw-2">&mut </span>[Limb], |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| parse_big_endian_and_pad_consttime(input, result)<span class="question-mark">?</span>; |
| <span class="kw">if </span>limbs_less_than_limbs_consttime(<span class="kw-2">&</span>result, max_exclusive) != LimbMask::True { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| <span class="kw">if </span>allow_zero != AllowZero::Yes { |
| <span class="kw">if </span>limbs_are_zero_constant_time(<span class="kw-2">&</span>result) != LimbMask::False { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| } |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="doccomment">/// Parses `input` into `result`, padding `result` with zeros to its length. |
| /// This attempts to be constant-time with respect to the value but not with |
| /// respect to the length; it is assumed that the length is public knowledge. |
| </span><span class="kw">pub fn </span>parse_big_endian_and_pad_consttime( |
| input: untrusted::Input, |
| result: <span class="kw-2">&mut </span>[Limb], |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">if </span>input.is_empty() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| |
| <span class="comment">// `bytes_in_current_limb` is the number of bytes in the current limb. |
| // It will be `LIMB_BYTES` for all limbs except maybe the highest-order |
| // limb. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>bytes_in_current_limb = input.len() % LIMB_BYTES; |
| <span class="kw">if </span>bytes_in_current_limb == <span class="number">0 </span>{ |
| bytes_in_current_limb = LIMB_BYTES; |
| } |
| |
| <span class="kw">let </span>num_encoded_limbs = (input.len() / LIMB_BYTES) |
| + (<span class="kw">if </span>bytes_in_current_limb == LIMB_BYTES { |
| <span class="number">0 |
| </span>} <span class="kw">else </span>{ |
| <span class="number">1 |
| </span>}); |
| <span class="kw">if </span>num_encoded_limbs > result.len() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| |
| <span class="kw">for </span>r <span class="kw">in </span><span class="kw-2">&mut </span>result[..] { |
| <span class="kw-2">*</span>r = <span class="number">0</span>; |
| } |
| |
| <span class="comment">// XXX: Questionable as far as constant-timedness is concerned. |
| // TODO: Improve this. |
| </span>input.read_all(error::Unspecified, |input| { |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..num_encoded_limbs { |
| <span class="kw">let </span><span class="kw-2">mut </span>limb: Limb = <span class="number">0</span>; |
| <span class="kw">for _ in </span><span class="number">0</span>..bytes_in_current_limb { |
| <span class="kw">let </span>b: Limb = input.read_byte()<span class="question-mark">?</span>.into(); |
| limb = (limb << <span class="number">8</span>) | b; |
| } |
| result[num_encoded_limbs - i - <span class="number">1</span>] = limb; |
| bytes_in_current_limb = LIMB_BYTES; |
| } |
| <span class="prelude-val">Ok</span>(()) |
| }) |
| } |
| |
| <span class="kw">pub fn </span>big_endian_from_limbs(limbs: <span class="kw-2">&</span>[Limb], out: <span class="kw-2">&mut </span>[u8]) { |
| <span class="kw">let </span>num_limbs = limbs.len(); |
| <span class="kw">let </span>out_len = out.len(); |
| <span class="macro">assert_eq!</span>(out_len, num_limbs * LIMB_BYTES); |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..num_limbs { |
| <span class="kw">let </span><span class="kw-2">mut </span>limb = limbs[i]; |
| <span class="kw">for </span>j <span class="kw">in </span><span class="number">0</span>..LIMB_BYTES { |
| out[((num_limbs - i - <span class="number">1</span>) * LIMB_BYTES) + (LIMB_BYTES - j - <span class="number">1</span>)] = (limb & <span class="number">0xff</span>) <span class="kw">as </span>u8; |
| limb >>= <span class="number">8</span>; |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">pub type </span>Window = Limb; |
| |
| <span class="doccomment">/// Processes `limbs` as a sequence of 5-bit windows, folding the windows from |
| /// most significant to least significant and returning the accumulated result. |
| /// The first window will be mapped by `init` to produce the initial value for |
| /// the accumulator. Then `f` will be called to fold the accumulator and the |
| /// next window until all windows are processed. When the input's bit length |
| /// isn't divisible by 5, the window passed to `init` will be partial; all |
| /// windows passed to `fold` will be full. |
| /// |
| /// This is designed to avoid leaking the contents of `limbs` through side |
| /// channels as long as `init` and `fold` are side-channel free. |
| /// |
| /// Panics if `limbs` is empty. |
| </span><span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">pub fn </span>fold_5_bit_windows<R, I: FnOnce(Window) -> R, F: Fn(R, Window) -> R>( |
| limbs: <span class="kw-2">&</span>[Limb], |
| init: I, |
| fold: F, |
| ) -> R { |
| <span class="attribute">#[derive(Clone, Copy)] |
| #[repr(transparent)] |
| </span><span class="kw">struct </span>BitIndex(Wrapping<c::size_t>); |
| |
| <span class="kw">const </span>WINDOW_BITS: Wrapping<c::size_t> = Wrapping(<span class="number">5</span>); |
| |
| <span class="kw">extern </span><span class="string">"C" </span>{ |
| <span class="kw">fn </span>LIMBS_window5_split_window( |
| lower_limb: Limb, |
| higher_limb: Limb, |
| index_within_word: BitIndex, |
| ) -> Window; |
| <span class="kw">fn </span>LIMBS_window5_unsplit_window(limb: Limb, index_within_word: BitIndex) -> Window; |
| } |
| |
| <span class="kw">let </span>num_limbs = limbs.len(); |
| <span class="kw">let </span><span class="kw-2">mut </span>window_low_bit = { |
| <span class="kw">let </span>num_whole_windows = (num_limbs * LIMB_BITS) / <span class="number">5</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>leading_bits = (num_limbs * LIMB_BITS) - (num_whole_windows * <span class="number">5</span>); |
| <span class="kw">if </span>leading_bits == <span class="number">0 </span>{ |
| leading_bits = WINDOW_BITS.<span class="number">0</span>; |
| } |
| BitIndex(Wrapping(LIMB_BITS - leading_bits)) |
| }; |
| |
| <span class="kw">let </span>initial_value = { |
| <span class="kw">let </span>leading_partial_window = |
| <span class="kw">unsafe </span>{ LIMBS_window5_split_window(<span class="kw-2">*</span>limbs.last().unwrap(), <span class="number">0</span>, window_low_bit) }; |
| window_low_bit.<span class="number">0 </span>-= WINDOW_BITS; |
| init(leading_partial_window) |
| }; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>low_limb = <span class="number">0</span>; |
| limbs |
| .iter() |
| .rev() |
| .fold(initial_value, |<span class="kw-2">mut </span>acc, current_limb| { |
| <span class="kw">let </span>higher_limb = low_limb; |
| low_limb = <span class="kw-2">*</span>current_limb; |
| |
| <span class="kw">if </span>window_low_bit.<span class="number">0 </span>> Wrapping(LIMB_BITS) - WINDOW_BITS { |
| <span class="kw">let </span>window = |
| <span class="kw">unsafe </span>{ LIMBS_window5_split_window(low_limb, higher_limb, window_low_bit) }; |
| window_low_bit.<span class="number">0 </span>-= WINDOW_BITS; |
| acc = fold(acc, window); |
| }; |
| <span class="kw">while </span>window_low_bit.<span class="number">0 </span>< Wrapping(LIMB_BITS) { |
| <span class="kw">let </span>window = <span class="kw">unsafe </span>{ LIMBS_window5_unsplit_window(low_limb, window_low_bit) }; |
| <span class="comment">// The loop exits when this subtraction underflows, causing `window_low_bit` to |
| // wrap around to a very large value. |
| </span>window_low_bit.<span class="number">0 </span>-= WINDOW_BITS; |
| acc = fold(acc, window); |
| } |
| window_low_bit.<span class="number">0 </span>+= Wrapping(LIMB_BITS); <span class="comment">// "Fix" the underflow. |
| |
| </span>acc |
| }) |
| } |
| |
| <span class="kw">extern </span><span class="string">"C" </span>{ |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">fn </span>LIMB_shr(a: Limb, shift: c::size_t) -> Limb; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">fn </span>LIMBS_are_even(a: <span class="kw-2">*const </span>Limb, num_limbs: c::size_t) -> LimbMask; |
| <span class="kw">fn </span>LIMBS_are_zero(a: <span class="kw-2">*const </span>Limb, num_limbs: c::size_t) -> LimbMask; |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">fn </span>LIMBS_equal_limb(a: <span class="kw-2">*const </span>Limb, b: Limb, num_limbs: c::size_t) -> LimbMask; |
| <span class="kw">fn </span>LIMBS_less_than(a: <span class="kw-2">*const </span>Limb, b: <span class="kw-2">*const </span>Limb, num_limbs: c::size_t) -> LimbMask; |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">fn </span>LIMBS_less_than_limb(a: <span class="kw-2">*const </span>Limb, b: Limb, num_limbs: c::size_t) -> LimbMask; |
| <span class="kw">fn </span>LIMBS_reduce_once(r: <span class="kw-2">*mut </span>Limb, m: <span class="kw-2">*const </span>Limb, num_limbs: c::size_t); |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="kw">const </span>MAX: Limb = LimbMask::True <span class="kw">as </span>Limb; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_limbs_are_even() { |
| <span class="kw">static </span>EVENS: <span class="kw-2">&</span>[<span class="kw-2">&</span>[Limb]] = <span class="kw-2">&</span>[ |
| <span class="kw-2">&</span>[], |
| <span class="kw-2">&</span>[<span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">2</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">2</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">1</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">2</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">3</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, MAX], |
| ]; |
| <span class="kw">for </span>even <span class="kw">in </span>EVENS { |
| <span class="macro">assert_eq!</span>(limbs_are_even_constant_time(even), LimbMask::True); |
| } |
| <span class="kw">static </span>ODDS: <span class="kw-2">&</span>[<span class="kw-2">&</span>[Limb]] = <span class="kw-2">&</span>[ |
| <span class="kw-2">&</span>[<span class="number">1</span>], |
| <span class="kw-2">&</span>[<span class="number">3</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">3</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">1</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">2</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">3</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, MAX], |
| ]; |
| <span class="kw">for </span>odd <span class="kw">in </span>ODDS { |
| <span class="macro">assert_eq!</span>(limbs_are_even_constant_time(odd), LimbMask::False); |
| } |
| } |
| |
| <span class="kw">static </span>ZEROES: <span class="kw-2">&</span>[<span class="kw-2">&</span>[Limb]] = <span class="kw-2">&</span>[ |
| <span class="kw-2">&</span>[], |
| <span class="kw-2">&</span>[<span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| ]; |
| |
| <span class="kw">static </span>NONZEROES: <span class="kw-2">&</span>[<span class="kw-2">&</span>[Limb]] = <span class="kw-2">&</span>[ |
| <span class="kw-2">&</span>[<span class="number">1</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">1</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">1</span>], |
| <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">0</span>], |
| <span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>], |
| ]; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_limbs_are_zero() { |
| <span class="kw">for </span>zero <span class="kw">in </span>ZEROES { |
| <span class="macro">assert_eq!</span>(limbs_are_zero_constant_time(zero), LimbMask::True); |
| } |
| <span class="kw">for </span>nonzero <span class="kw">in </span>NONZEROES { |
| <span class="macro">assert_eq!</span>(limbs_are_zero_constant_time(nonzero), LimbMask::False); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_limbs_equal_limb() { |
| <span class="kw">for </span>zero <span class="kw">in </span>ZEROES { |
| <span class="macro">assert_eq!</span>(limbs_equal_limb_constant_time(zero, <span class="number">0</span>), LimbMask::True); |
| } |
| <span class="kw">for </span>nonzero <span class="kw">in </span>NONZEROES { |
| <span class="macro">assert_eq!</span>(limbs_equal_limb_constant_time(nonzero, <span class="number">0</span>), LimbMask::False); |
| } |
| <span class="kw">static </span>EQUAL: <span class="kw-2">&</span>[(<span class="kw-2">&</span>[Limb], Limb)] = <span class="kw-2">&</span>[ |
| (<span class="kw-2">&</span>[<span class="number">1</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[MAX], MAX), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[MAX, <span class="number">0</span>, <span class="number">0</span>], MAX), |
| (<span class="kw-2">&</span>[<span class="number">0b100</span>], <span class="number">0b100</span>), |
| (<span class="kw-2">&</span>[<span class="number">0b100</span>, <span class="number">0</span>], <span class="number">0b100</span>), |
| ]; |
| <span class="kw">for </span><span class="kw-2">&</span>(a, b) <span class="kw">in </span>EQUAL { |
| <span class="macro">assert_eq!</span>(limbs_equal_limb_constant_time(a, b), LimbMask::True); |
| } |
| <span class="kw">static </span>UNEQUAL: <span class="kw-2">&</span>[(<span class="kw-2">&</span>[Limb], Limb)] = <span class="kw-2">&</span>[ |
| (<span class="kw-2">&</span>[<span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">2</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">3</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">1</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0b100</span>, <span class="number">0b100</span>], <span class="number">0b100</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>, <span class="number">0b100</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0b100</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[MAX, MAX], MAX), |
| (<span class="kw-2">&</span>[MAX, <span class="number">1</span>], MAX), |
| ]; |
| <span class="kw">for </span><span class="kw-2">&</span>(a, b) <span class="kw">in </span>UNEQUAL { |
| <span class="macro">assert_eq!</span>(limbs_equal_limb_constant_time(a, b), LimbMask::False); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| #[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">fn </span>test_limbs_less_than_limb_constant_time() { |
| <span class="kw">static </span>LESSER: <span class="kw-2">&</span>[(<span class="kw-2">&</span>[Limb], Limb)] = <span class="kw-2">&</span>[ |
| (<span class="kw-2">&</span>[<span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>], <span class="number">2</span>), |
| (<span class="kw-2">&</span>[<span class="number">2</span>, <span class="number">0</span>], <span class="number">3</span>), |
| (<span class="kw-2">&</span>[<span class="number">2</span>, <span class="number">0</span>], <span class="number">3</span>), |
| (<span class="kw-2">&</span>[MAX - <span class="number">1</span>], MAX), |
| (<span class="kw-2">&</span>[MAX - <span class="number">1</span>, <span class="number">0</span>], MAX), |
| ]; |
| <span class="kw">for </span><span class="kw-2">&</span>(a, b) <span class="kw">in </span>LESSER { |
| <span class="macro">assert_eq!</span>(limbs_less_than_limb_constant_time(a, b), LimbMask::True); |
| } |
| <span class="kw">static </span>EQUAL: <span class="kw-2">&</span>[(<span class="kw-2">&</span>[Limb], Limb)] = <span class="kw-2">&</span>[ |
| (<span class="kw-2">&</span>[<span class="number">0</span>], <span class="number">0</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="number">0</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[MAX], MAX), |
| ]; |
| <span class="kw">static </span>GREATER: <span class="kw-2">&</span>[(<span class="kw-2">&</span>[Limb], Limb)] = <span class="kw-2">&</span>[ |
| (<span class="kw-2">&</span>[<span class="number">1</span>], <span class="number">0</span>), |
| (<span class="kw-2">&</span>[<span class="number">2</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">3</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">1</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[MAX], MAX - <span class="number">1</span>), |
| ]; |
| <span class="kw">for </span><span class="kw-2">&</span>(a, b) <span class="kw">in </span>EQUAL.iter().chain(GREATER.iter()) { |
| <span class="macro">assert_eq!</span>(limbs_less_than_limb_constant_time(a, b), LimbMask::False); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_parse_big_endian_and_pad_consttime() { |
| <span class="kw">const </span>LIMBS: usize = <span class="number">4</span>; |
| |
| { |
| <span class="comment">// Empty input. |
| </span><span class="kw">let </span>inp = untrusted::Input::from(<span class="kw-2">&</span>[]); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = [<span class="number">0</span>; LIMBS]; |
| <span class="macro">assert!</span>(parse_big_endian_and_pad_consttime(inp, <span class="kw-2">&mut </span>result).is_err()); |
| } |
| |
| <span class="comment">// The input is longer than will fit in the given number of limbs. |
| </span>{ |
| <span class="kw">let </span>inp = [<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="number">8</span>, <span class="number">9</span>]; |
| <span class="kw">let </span>inp = untrusted::Input::from(<span class="kw-2">&</span>inp); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = [<span class="number">0</span>; <span class="number">8 </span>/ LIMB_BYTES]; |
| <span class="macro">assert!</span>(parse_big_endian_and_pad_consttime(inp, <span class="kw-2">&mut </span>result[..]).is_err()); |
| } |
| |
| <span class="comment">// Less than a full limb. |
| </span>{ |
| <span class="kw">let </span>inp = [<span class="number">0xfe</span>]; |
| <span class="kw">let </span>inp = untrusted::Input::from(<span class="kw-2">&</span>inp); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = [<span class="number">0</span>; LIMBS]; |
| <span class="macro">assert_eq!</span>( |
| <span class="prelude-val">Ok</span>(()), |
| parse_big_endian_and_pad_consttime(inp, <span class="kw-2">&mut </span>result[..]) |
| ); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>[<span class="number">0xfe</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="kw-2">&</span>result); |
| } |
| |
| <span class="comment">// A whole limb for 32-bit, half a limb for 64-bit. |
| </span>{ |
| <span class="kw">let </span>inp = [<span class="number">0xbe</span>, <span class="number">0xef</span>, <span class="number">0xf0</span>, <span class="number">0x0d</span>]; |
| <span class="kw">let </span>inp = untrusted::Input::from(<span class="kw-2">&</span>inp); |
| <span class="kw">let </span><span class="kw-2">mut </span>result = [<span class="number">0</span>; LIMBS]; |
| <span class="macro">assert_eq!</span>(<span class="prelude-val">Ok</span>(()), parse_big_endian_and_pad_consttime(inp, <span class="kw-2">&mut </span>result)); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>[<span class="number">0xbeeff00d</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="kw-2">&</span>result); |
| } |
| |
| <span class="comment">// XXX: This is a weak set of tests. TODO: expand it. |
| </span>} |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_big_endian_from_limbs_same_length() { |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"32"</span>)] |
| </span><span class="kw">let </span>limbs = [ |
| <span class="number">0xbccddeef</span>, <span class="number">0x89900aab</span>, <span class="number">0x45566778</span>, <span class="number">0x01122334</span>, <span class="number">0xddeeff00</span>, <span class="number">0x99aabbcc</span>, <span class="number">0x55667788</span>, |
| <span class="number">0x11223344</span>, |
| ]; |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| </span><span class="kw">let </span>limbs = [ |
| <span class="number">0x8990_0aab_bccd_deef</span>, |
| <span class="number">0x0112_2334_4556_6778</span>, |
| <span class="number">0x99aa_bbcc_ddee_ff00</span>, |
| <span class="number">0x1122_3344_5566_7788</span>, |
| ]; |
| |
| <span class="kw">let </span>expected = [ |
| <span class="number">0x11</span>, <span class="number">0x22</span>, <span class="number">0x33</span>, <span class="number">0x44</span>, <span class="number">0x55</span>, <span class="number">0x66</span>, <span class="number">0x77</span>, <span class="number">0x88</span>, <span class="number">0x99</span>, <span class="number">0xaa</span>, <span class="number">0xbb</span>, <span class="number">0xcc</span>, <span class="number">0xdd</span>, <span class="number">0xee</span>, |
| <span class="number">0xff</span>, <span class="number">0x00</span>, <span class="number">0x01</span>, <span class="number">0x12</span>, <span class="number">0x23</span>, <span class="number">0x34</span>, <span class="number">0x45</span>, <span class="number">0x56</span>, <span class="number">0x67</span>, <span class="number">0x78</span>, <span class="number">0x89</span>, <span class="number">0x90</span>, <span class="number">0x0a</span>, <span class="number">0xab</span>, |
| <span class="number">0xbc</span>, <span class="number">0xcd</span>, <span class="number">0xde</span>, <span class="number">0xef</span>, |
| ]; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>out = [<span class="number">0xabu8</span>; <span class="number">32</span>]; |
| big_endian_from_limbs(<span class="kw-2">&</span>limbs[..], <span class="kw-2">&mut </span>out); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>out[..], <span class="kw-2">&</span>expected[..]); |
| } |
| |
| <span class="attribute">#[should_panic] |
| #[test] |
| </span><span class="kw">fn </span>test_big_endian_from_limbs_fewer_limbs() { |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"32"</span>)] |
| </span><span class="comment">// Two fewer limbs. |
| </span><span class="kw">let </span>limbs = [ |
| <span class="number">0xbccddeef</span>, <span class="number">0x89900aab</span>, <span class="number">0x45566778</span>, <span class="number">0x01122334</span>, <span class="number">0xddeeff00</span>, <span class="number">0x99aabbcc</span>, |
| ]; |
| |
| <span class="comment">// One fewer limb. |
| </span><span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| </span><span class="kw">let </span>limbs = [ |
| <span class="number">0x8990_0aab_bccd_deef</span>, |
| <span class="number">0x0112_2334_4556_6778</span>, |
| <span class="number">0x99aa_bbcc_ddee_ff00</span>, |
| ]; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>out = [<span class="number">0xabu8</span>; <span class="number">32</span>]; |
| |
| big_endian_from_limbs(<span class="kw-2">&</span>limbs[..], <span class="kw-2">&mut </span>out); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_limbs_minimal_bits() { |
| <span class="kw">const </span>ALL_ONES: Limb = LimbMask::True <span class="kw">as </span>Limb; |
| <span class="kw">static </span>CASES: <span class="kw-2">&</span>[(<span class="kw-2">&</span>[Limb], usize)] = <span class="kw-2">&</span>[ |
| (<span class="kw-2">&</span>[], <span class="number">0</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>], <span class="number">0</span>), |
| (<span class="kw-2">&</span>[ALL_ONES], LIMB_BITS), |
| (<span class="kw-2">&</span>[ALL_ONES, <span class="number">0</span>], LIMB_BITS), |
| (<span class="kw-2">&</span>[ALL_ONES, <span class="number">1</span>], LIMB_BITS + <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">0</span>], <span class="number">0</span>), |
| (<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">0</span>], <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, <span class="number">1</span>], LIMB_BITS + <span class="number">1</span>), |
| (<span class="kw-2">&</span>[<span class="number">0</span>, ALL_ONES], <span class="number">2 </span>* LIMB_BITS), |
| (<span class="kw-2">&</span>[ALL_ONES, ALL_ONES], <span class="number">2 </span>* LIMB_BITS), |
| (<span class="kw-2">&</span>[ALL_ONES, ALL_ONES >> <span class="number">1</span>], <span class="number">2 </span>* LIMB_BITS - <span class="number">1</span>), |
| (<span class="kw-2">&</span>[ALL_ONES, <span class="number">0b100_0000</span>], LIMB_BITS + <span class="number">7</span>), |
| (<span class="kw-2">&</span>[ALL_ONES, <span class="number">0b101_0000</span>], LIMB_BITS + <span class="number">7</span>), |
| (<span class="kw-2">&</span>[ALL_ONES, ALL_ONES >> <span class="number">1</span>], LIMB_BITS + (LIMB_BITS) - <span class="number">1</span>), |
| ]; |
| <span class="kw">for </span>(limbs, bits) <span class="kw">in </span>CASES { |
| <span class="macro">assert_eq!</span>(limbs_minimal_bits(limbs).as_usize_bits(), <span class="kw-2">*</span>bits); |
| } |
| } |
| } |
| </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> |
