| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/git/checkouts/incubator-teaclave-crates-c8106113f74feefc/ede1f68/ring/src/ec/suite_b/private_key.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>private_key.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../ring/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../ring/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="comment">// Copyright 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">//! Functionality shared by operations on private keys (ECC keygen and |
| //! ECDSA signing). |
| |
| </span><span class="kw">use super</span>::{ops::<span class="kw-2">*</span>, verify_affine_point_is_on_the_curve}; |
| <span class="kw">use crate</span>::{ |
| arithmetic::montgomery::R, |
| ec, error, |
| limb::{<span class="self">self</span>, LIMB_BYTES}, |
| rand, |
| }; |
| |
| <span class="doccomment">/// Generates a random scalar in the range [1, n). |
| </span><span class="kw">pub fn </span>random_scalar( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| rng: <span class="kw-2">&</span><span class="kw">dyn </span>rand::SecureRandom, |
| ) -> <span class="prelude-ty">Result</span><Scalar, error::Unspecified> { |
| <span class="kw">let </span>num_limbs = ops.common.num_limbs; |
| <span class="kw">let </span><span class="kw-2">mut </span>bytes = [<span class="number">0</span>; ec::SCALAR_MAX_BYTES]; |
| <span class="kw">let </span>bytes = <span class="kw-2">&mut </span>bytes[..(num_limbs * LIMB_BYTES)]; |
| generate_private_scalar_bytes(ops, rng, bytes)<span class="question-mark">?</span>; |
| scalar_from_big_endian_bytes(ops, bytes) |
| } |
| |
| <span class="kw">pub fn </span>generate_private_scalar_bytes( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| rng: <span class="kw-2">&</span><span class="kw">dyn </span>rand::SecureRandom, |
| out: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="comment">// [NSA Suite B Implementer's Guide to ECDSA] Appendix A.1.2, and |
| // [NSA Suite B Implementer's Guide to NIST SP 800-56A] Appendix B.2, |
| // "Key Pair Generation by Testing Candidates". |
| // |
| // [NSA Suite B Implementer's Guide to ECDSA]: doc/ecdsa.pdf. |
| // [NSA Suite B Implementer's Guide to NIST SP 800-56A]: doc/ecdh.pdf. |
| |
| // TODO: The NSA guide also suggests, in appendix B.1, another mechanism |
| // that would avoid the need to use `rng.fill()` more than once. It works |
| // by generating an extra 64 bits of random bytes and then reducing the |
| // output (mod n). Supposedly, this removes enough of the bias towards |
| // small values from the modular reduction, but it isn't obvious that it is |
| // sufficient. TODO: Figure out what we can do to mitigate the bias issue |
| // and switch to the other mechanism. |
| |
| </span><span class="kw">let </span>candidate = out; |
| |
| <span class="comment">// XXX: The value 100 was chosen to match OpenSSL due to uncertainty of |
| // what specific value would be better, but it seems bad to try 100 times. |
| </span><span class="kw">for _ in </span><span class="number">0</span>..<span class="number">100 </span>{ |
| <span class="comment">// NSA Guide Steps 1, 2, and 3. |
| // |
| // Since we calculate the length ourselves, it is pointless to check |
| // it, since we can only check it by doing the same calculation. |
| |
| // NSA Guide Step 4. |
| // |
| // The requirement that the random number generator has the |
| // requested security strength is delegated to `rng`. |
| </span>rng.fill(candidate)<span class="question-mark">?</span>; |
| |
| <span class="comment">// NSA Guide Steps 5, 6, and 7. |
| </span><span class="kw">if </span>check_scalar_big_endian_bytes(ops, candidate).is_err() { |
| <span class="kw">continue</span>; |
| } |
| |
| <span class="comment">// NSA Guide Step 8 is done in `public_from_private()`. |
| |
| // NSA Guide Step 9. |
| </span><span class="kw">return </span><span class="prelude-val">Ok</span>(()); |
| } |
| |
| <span class="prelude-val">Err</span>(error::Unspecified) |
| } |
| |
| <span class="comment">// The underlying X25519 and Ed25519 code uses an [u8; 32] to store the private |
| // key. To make the ECDH and ECDSA code similar to that, we also store the |
| // private key that way, which means we have to convert it to a Scalar whenever |
| // we need to use it. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>private_key_as_scalar(ops: <span class="kw-2">&</span>PrivateKeyOps, private_key: <span class="kw-2">&</span>ec::Seed) -> Scalar { |
| <span class="comment">// This cannot fail because we know the private key is valid. |
| </span>scalar_from_big_endian_bytes(ops, private_key.bytes_less_safe()).unwrap() |
| } |
| |
| <span class="kw">pub fn </span>check_scalar_big_endian_bytes( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| bytes: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="macro">debug_assert_eq!</span>(bytes.len(), ops.common.num_limbs * LIMB_BYTES); |
| scalar_from_big_endian_bytes(ops, bytes).map(|<span class="kw">_</span>| ()) |
| } |
| |
| <span class="comment">// Parses a fixed-length (zero-padded) big-endian-encoded scalar in the range |
| // [1, n). This is 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>scalar_from_big_endian_bytes( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| bytes: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Result</span><Scalar, error::Unspecified> { |
| <span class="comment">// [NSA Suite B Implementer's Guide to ECDSA] Appendix A.1.2, and |
| // [NSA Suite B Implementer's Guide to NIST SP 800-56A] Appendix B.2, |
| // "Key Pair Generation by Testing Candidates". |
| // |
| // [NSA Suite B Implementer's Guide to ECDSA]: doc/ecdsa.pdf. |
| // [NSA Suite B Implementer's Guide to NIST SP 800-56A]: doc/ecdh.pdf. |
| // |
| // Steps 5, 6, and 7. |
| // |
| // XXX: The NSA guide says that we should verify that the random scalar is |
| // in the range [0, n - 1) and then add one to it so that it is in the range |
| // [1, n). Instead, we verify that the scalar is in the range [1, n). This |
| // way, we avoid needing to compute or store the value (n - 1), we avoid the |
| // need to implement a function to add one to a scalar, and we avoid needing |
| // to convert the scalar back into an array of bytes. |
| </span>scalar_parse_big_endian_fixed_consttime(ops.common, untrusted::Input::from(bytes)) |
| } |
| |
| <span class="kw">pub fn </span>public_from_private( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| public_out: <span class="kw-2">&mut </span>[u8], |
| my_private_key: <span class="kw-2">&</span>ec::Seed, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">let </span>elem_and_scalar_bytes = ops.common.num_limbs * LIMB_BYTES; |
| <span class="macro">debug_assert_eq!</span>(public_out.len(), <span class="number">1 </span>+ (<span class="number">2 </span>* elem_and_scalar_bytes)); |
| <span class="kw">let </span>my_private_key = private_key_as_scalar(ops, my_private_key); |
| <span class="kw">let </span>my_public_key = ops.point_mul_base(<span class="kw-2">&</span>my_private_key); |
| public_out[<span class="number">0</span>] = <span class="number">4</span>; <span class="comment">// Uncompressed encoding. |
| </span><span class="kw">let </span>(x_out, y_out) = (<span class="kw-2">&mut </span>public_out[<span class="number">1</span>..]).split_at_mut(elem_and_scalar_bytes); |
| |
| <span class="comment">// `big_endian_affine_from_jacobian` verifies that the point is not at |
| // infinity and is on the curve. |
| </span>big_endian_affine_from_jacobian(ops, <span class="prelude-val">Some</span>(x_out), <span class="prelude-val">Some</span>(y_out), <span class="kw-2">&</span>my_public_key) |
| } |
| |
| <span class="kw">pub fn </span>affine_from_jacobian( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| p: <span class="kw-2">&</span>Point, |
| ) -> <span class="prelude-ty">Result</span><(Elem<R>, Elem<R>), error::Unspecified> { |
| <span class="kw">let </span>z = ops.common.point_z(p); |
| |
| <span class="comment">// Since we restrict our private key to the range [1, n), the curve has |
| // prime order, and we verify that the peer's point is on the curve, |
| // there's no way that the result can be at infinity. But, use `assert!` |
| // instead of `debug_assert!` anyway |
| </span><span class="macro">assert!</span>(ops.common.elem_verify_is_not_zero(<span class="kw-2">&</span>z).is_ok()); |
| |
| <span class="kw">let </span>x = ops.common.point_x(p); |
| <span class="kw">let </span>y = ops.common.point_y(p); |
| |
| <span class="kw">let </span>zz_inv = ops.elem_inverse_squared(<span class="kw-2">&</span>z); |
| |
| <span class="kw">let </span>x_aff = ops.common.elem_product(<span class="kw-2">&</span>x, <span class="kw-2">&</span>zz_inv); |
| |
| <span class="comment">// `y_aff` is needed to validate the point is on the curve. It is also |
| // needed in the non-ECDH case where we need to output it. |
| </span><span class="kw">let </span>y_aff = { |
| <span class="kw">let </span>zzzz_inv = ops.common.elem_squared(<span class="kw-2">&</span>zz_inv); |
| <span class="kw">let </span>zzz_inv = ops.common.elem_product(<span class="kw-2">&</span>z, <span class="kw-2">&</span>zzzz_inv); |
| ops.common.elem_product(<span class="kw-2">&</span>y, <span class="kw-2">&</span>zzz_inv) |
| }; |
| |
| <span class="comment">// If we validated our inputs correctly and then computed (x, y, z), then |
| // (x, y, z) will be on the curve. See |
| // `verify_affine_point_is_on_the_curve_scaled` for the motivation. |
| </span>verify_affine_point_is_on_the_curve(ops.common, (<span class="kw-2">&</span>x_aff, <span class="kw-2">&</span>y_aff))<span class="question-mark">?</span>; |
| |
| <span class="prelude-val">Ok</span>((x_aff, y_aff)) |
| } |
| |
| <span class="kw">pub fn </span>big_endian_affine_from_jacobian( |
| ops: <span class="kw-2">&</span>PrivateKeyOps, |
| x_out: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>[u8]>, |
| y_out: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>[u8]>, |
| p: <span class="kw-2">&</span>Point, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">let </span>(x_aff, y_aff) = affine_from_jacobian(ops, p)<span class="question-mark">?</span>; |
| <span class="kw">let </span>num_limbs = ops.common.num_limbs; |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(x_out) = x_out { |
| <span class="kw">let </span>x = ops.common.elem_unencoded(<span class="kw-2">&</span>x_aff); |
| limb::big_endian_from_limbs(<span class="kw-2">&</span>x.limbs[..num_limbs], x_out); |
| } |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(y_out) = y_out { |
| <span class="kw">let </span>y = ops.common.elem_unencoded(<span class="kw-2">&</span>y_aff); |
| limb::big_endian_from_limbs(<span class="kw-2">&</span>y.limbs[..num_limbs], y_out); |
| } |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| </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> |
