| <!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/rsa/padding.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>padding.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="601">601</span> |
| </pre><pre class="rust"><code><span class="comment">// Copyright 2015-2016 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="kw">use </span><span class="kw">super</span>::PUBLIC_KEY_PUBLIC_MODULUS_MAX_LEN; |
| <span class="kw">use crate</span>::{bits, digest, error, io::der}; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">use </span><span class="kw">crate</span>::rand; |
| |
| <span class="doccomment">/// Common features of both RSA padding encoding and RSA padding verification. |
| </span><span class="kw">pub trait </span>Padding: <span class="lifetime">'static </span>+ Sync + <span class="kw">crate</span>::sealed::Sealed + core::fmt::Debug { |
| <span class="comment">// The digest algorithm used for digesting the message (and maybe for |
| // other things). |
| </span><span class="kw">fn </span>digest_alg(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm; |
| } |
| |
| <span class="doccomment">/// An RSA signature encoding as described in [RFC 3447 Section 8]. |
| /// |
| /// [RFC 3447 Section 8]: https://tools.ietf.org/html/rfc3447#section-8 |
| </span><span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">pub trait </span>RsaEncoding: Padding { |
| <span class="attribute">#[doc(hidden)] |
| </span><span class="kw">fn </span>encode( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| m_out: <span class="kw-2">&mut </span>[u8], |
| mod_bits: bits::BitLength, |
| rng: <span class="kw-2">&</span><span class="kw">dyn </span>rand::SecureRandom, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified>; |
| } |
| |
| <span class="doccomment">/// Verification of an RSA signature encoding as described in |
| /// [RFC 3447 Section 8]. |
| /// |
| /// [RFC 3447 Section 8]: https://tools.ietf.org/html/rfc3447#section-8 |
| </span><span class="kw">pub trait </span>Verification: Padding { |
| <span class="kw">fn </span>verify( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| m: <span class="kw-2">&mut </span>untrusted::Reader, |
| mod_bits: bits::BitLength, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified>; |
| } |
| |
| <span class="doccomment">/// PKCS#1 1.5 padding as described in [RFC 3447 Section 8.2]. |
| /// |
| /// See "`RSA_PSS_*` Details\" in `ring::signature`'s module-level |
| /// documentation for more details. |
| /// |
| /// [RFC 3447 Section 8.2]: https://tools.ietf.org/html/rfc3447#section-8.2 |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>PKCS1 { |
| digest_alg: <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm, |
| digestinfo_prefix: <span class="kw-2">&</span><span class="lifetime">'static </span>[u8], |
| } |
| |
| <span class="kw">impl </span><span class="kw">crate</span>::sealed::Sealed <span class="kw">for </span>PKCS1 {} |
| |
| <span class="kw">impl </span>Padding <span class="kw">for </span>PKCS1 { |
| <span class="kw">fn </span>digest_alg(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm { |
| <span class="self">self</span>.digest_alg |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| </span><span class="kw">impl </span>RsaEncoding <span class="kw">for </span>PKCS1 { |
| <span class="kw">fn </span>encode( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| m_out: <span class="kw-2">&mut </span>[u8], |
| _mod_bits: bits::BitLength, |
| _rng: <span class="kw-2">&</span><span class="kw">dyn </span>rand::SecureRandom, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| pkcs1_encode(<span class="kw-2">&</span><span class="self">self</span>, m_hash, m_out); |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="kw">impl </span>Verification <span class="kw">for </span>PKCS1 { |
| <span class="kw">fn </span>verify( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| m: <span class="kw-2">&mut </span>untrusted::Reader, |
| mod_bits: bits::BitLength, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="comment">// `mod_bits.as_usize_bytes_rounded_up() <= |
| // PUBLIC_KEY_PUBLIC_MODULUS_MAX_LEN` is ensured by `verify_rsa_()`. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>calculated = [<span class="number">0u8</span>; PUBLIC_KEY_PUBLIC_MODULUS_MAX_LEN]; |
| <span class="kw">let </span>calculated = <span class="kw-2">&mut </span>calculated[..mod_bits.as_usize_bytes_rounded_up()]; |
| pkcs1_encode(<span class="kw-2">&</span><span class="self">self</span>, m_hash, calculated); |
| <span class="kw">if </span>m.read_bytes_to_end() != <span class="kw-2">*</span>calculated { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="comment">// Implement padding procedure per EMSA-PKCS1-v1_5, |
| // https://tools.ietf.org/html/rfc3447#section-9.2. This is used by both |
| // verification and signing so it needs to be able to handle moduli of the |
| // minimum and maximum sizes for both operations. |
| </span><span class="kw">fn </span>pkcs1_encode(pkcs1: <span class="kw-2">&</span>PKCS1, m_hash: <span class="kw-2">&</span>digest::Digest, m_out: <span class="kw-2">&mut </span>[u8]) { |
| <span class="kw">let </span>em = m_out; |
| |
| <span class="kw">let </span>digest_len = pkcs1.digestinfo_prefix.len() + pkcs1.digest_alg.output_len; |
| |
| <span class="comment">// The specification requires at least 8 bytes of padding. Since we |
| // disallow keys smaller than 1024 bits, this should always be true. |
| </span><span class="macro">assert!</span>(em.len() >= digest_len + <span class="number">11</span>); |
| <span class="kw">let </span>pad_len = em.len() - digest_len - <span class="number">3</span>; |
| em[<span class="number">0</span>] = <span class="number">0</span>; |
| em[<span class="number">1</span>] = <span class="number">1</span>; |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..pad_len { |
| em[<span class="number">2 </span>+ i] = <span class="number">0xff</span>; |
| } |
| em[<span class="number">2 </span>+ pad_len] = <span class="number">0</span>; |
| |
| <span class="kw">let </span>(digest_prefix, digest_dst) = em[<span class="number">3 </span>+ pad_len..].split_at_mut(pkcs1.digestinfo_prefix.len()); |
| digest_prefix.copy_from_slice(pkcs1.digestinfo_prefix); |
| digest_dst.copy_from_slice(m_hash.as_ref()); |
| } |
| |
| <span class="macro">macro_rules! </span>rsa_pkcs1_padding { |
| ( <span class="macro-nonterminal">$PADDING_ALGORITHM</span>:ident, <span class="macro-nonterminal">$digest_alg</span>:expr, <span class="macro-nonterminal">$digestinfo_prefix</span>:expr, |
| <span class="macro-nonterminal">$doc_str</span>:expr ) => { |
| <span class="attribute">#[doc=<span class="macro-nonterminal">$doc_str</span>] |
| </span><span class="kw">pub static </span><span class="macro-nonterminal">$PADDING_ALGORITHM</span>: PKCS1 = PKCS1 { |
| digest_alg: <span class="macro-nonterminal">$digest_alg</span>, |
| digestinfo_prefix: <span class="macro-nonterminal">$digestinfo_prefix</span>, |
| }; |
| }; |
| } |
| |
| <span class="macro">rsa_pkcs1_padding!</span>( |
| RSA_PKCS1_SHA1_FOR_LEGACY_USE_ONLY, |
| <span class="kw-2">&</span>digest::SHA1_FOR_LEGACY_USE_ONLY, |
| <span class="kw-2">&</span>SHA1_PKCS1_DIGESTINFO_PREFIX, |
| <span class="string">"PKCS#1 1.5 padding using SHA-1 for RSA signatures." |
| </span>); |
| <span class="macro">rsa_pkcs1_padding!</span>( |
| RSA_PKCS1_SHA256, |
| <span class="kw-2">&</span>digest::SHA256, |
| <span class="kw-2">&</span>SHA256_PKCS1_DIGESTINFO_PREFIX, |
| <span class="string">"PKCS#1 1.5 padding using SHA-256 for RSA signatures." |
| </span>); |
| <span class="macro">rsa_pkcs1_padding!</span>( |
| RSA_PKCS1_SHA384, |
| <span class="kw-2">&</span>digest::SHA384, |
| <span class="kw-2">&</span>SHA384_PKCS1_DIGESTINFO_PREFIX, |
| <span class="string">"PKCS#1 1.5 padding using SHA-384 for RSA signatures." |
| </span>); |
| <span class="macro">rsa_pkcs1_padding!</span>( |
| RSA_PKCS1_SHA512, |
| <span class="kw-2">&</span>digest::SHA512, |
| <span class="kw-2">&</span>SHA512_PKCS1_DIGESTINFO_PREFIX, |
| <span class="string">"PKCS#1 1.5 padding using SHA-512 for RSA signatures." |
| </span>); |
| |
| <span class="macro">macro_rules! </span>pkcs1_digestinfo_prefix { |
| ( <span class="macro-nonterminal">$name</span>:ident, <span class="macro-nonterminal">$digest_len</span>:expr, <span class="macro-nonterminal">$digest_oid_len</span>:expr, |
| [ $( <span class="macro-nonterminal">$digest_oid</span>:expr ),* ] ) => { |
| <span class="kw">static </span><span class="macro-nonterminal">$name</span>: [u8; <span class="number">2 </span>+ <span class="number">8 </span>+ <span class="macro-nonterminal">$digest_oid_len</span>] = [ |
| der::Tag::Sequence <span class="kw">as </span>u8, <span class="number">8 </span>+ <span class="macro-nonterminal">$digest_oid_len </span>+ <span class="macro-nonterminal">$digest_len</span>, |
| der::Tag::Sequence <span class="kw">as </span>u8, <span class="number">2 </span>+ <span class="macro-nonterminal">$digest_oid_len </span>+ <span class="number">2</span>, |
| der::Tag::OID <span class="kw">as </span>u8, <span class="macro-nonterminal">$digest_oid_len</span>, $( <span class="macro-nonterminal">$digest_oid </span>),<span class="kw-2">*</span>, |
| der::Tag::Null <span class="kw">as </span>u8, <span class="number">0</span>, |
| der::Tag::OctetString <span class="kw">as </span>u8, <span class="macro-nonterminal">$digest_len</span>, |
| ]; |
| } |
| } |
| |
| <span class="macro">pkcs1_digestinfo_prefix!</span>( |
| SHA1_PKCS1_DIGESTINFO_PREFIX, |
| <span class="number">20</span>, |
| <span class="number">5</span>, |
| [<span class="number">0x2b</span>, <span class="number">0x0e</span>, <span class="number">0x03</span>, <span class="number">0x02</span>, <span class="number">0x1a</span>] |
| ); |
| |
| <span class="macro">pkcs1_digestinfo_prefix!</span>( |
| SHA256_PKCS1_DIGESTINFO_PREFIX, |
| <span class="number">32</span>, |
| <span class="number">9</span>, |
| [<span class="number">0x60</span>, <span class="number">0x86</span>, <span class="number">0x48</span>, <span class="number">0x01</span>, <span class="number">0x65</span>, <span class="number">0x03</span>, <span class="number">0x04</span>, <span class="number">0x02</span>, <span class="number">0x01</span>] |
| ); |
| |
| <span class="macro">pkcs1_digestinfo_prefix!</span>( |
| SHA384_PKCS1_DIGESTINFO_PREFIX, |
| <span class="number">48</span>, |
| <span class="number">9</span>, |
| [<span class="number">0x60</span>, <span class="number">0x86</span>, <span class="number">0x48</span>, <span class="number">0x01</span>, <span class="number">0x65</span>, <span class="number">0x03</span>, <span class="number">0x04</span>, <span class="number">0x02</span>, <span class="number">0x02</span>] |
| ); |
| |
| <span class="macro">pkcs1_digestinfo_prefix!</span>( |
| SHA512_PKCS1_DIGESTINFO_PREFIX, |
| <span class="number">64</span>, |
| <span class="number">9</span>, |
| [<span class="number">0x60</span>, <span class="number">0x86</span>, <span class="number">0x48</span>, <span class="number">0x01</span>, <span class="number">0x65</span>, <span class="number">0x03</span>, <span class="number">0x04</span>, <span class="number">0x02</span>, <span class="number">0x03</span>] |
| ); |
| |
| <span class="doccomment">/// RSA PSS padding as described in [RFC 3447 Section 8.1]. |
| /// |
| /// See "`RSA_PSS_*` Details\" in `ring::signature`'s module-level |
| /// documentation for more details. |
| /// |
| /// [RFC 3447 Section 8.1]: https://tools.ietf.org/html/rfc3447#section-8.1 |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>PSS { |
| digest_alg: <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm, |
| } |
| |
| <span class="kw">impl </span><span class="kw">crate</span>::sealed::Sealed <span class="kw">for </span>PSS {} |
| |
| <span class="comment">// Maximum supported length of the salt in bytes. |
| // In practice, this is constrained by the maximum digest length. |
| </span><span class="kw">const </span>MAX_SALT_LEN: usize = digest::MAX_OUTPUT_LEN; |
| |
| <span class="kw">impl </span>Padding <span class="kw">for </span>PSS { |
| <span class="kw">fn </span>digest_alg(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm { |
| <span class="self">self</span>.digest_alg |
| } |
| } |
| |
| <span class="kw">impl </span>RsaEncoding <span class="kw">for </span>PSS { |
| <span class="comment">// Implement padding procedure per EMSA-PSS, |
| // https://tools.ietf.org/html/rfc3447#section-9.1. |
| </span><span class="kw">fn </span>encode( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| m_out: <span class="kw-2">&mut </span>[u8], |
| mod_bits: bits::BitLength, |
| rng: <span class="kw-2">&</span><span class="kw">dyn </span>rand::SecureRandom, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">let </span>metrics = PSSMetrics::new(<span class="self">self</span>.digest_alg, mod_bits)<span class="question-mark">?</span>; |
| |
| <span class="comment">// The `m_out` this function fills is the big-endian-encoded value of `m` |
| // from the specification, padded to `k` bytes, where `k` is the length |
| // in bytes of the public modulus. The spec says "Note that emLen will |
| // be one less than k if modBits - 1 is divisible by 8 and equal to k |
| // otherwise." In other words we might need to prefix `em` with a |
| // leading zero byte to form a correct value of `m`. |
| </span><span class="kw">let </span>em = <span class="kw">if </span>metrics.top_byte_mask == <span class="number">0xff </span>{ |
| m_out[<span class="number">0</span>] = <span class="number">0</span>; |
| <span class="kw-2">&mut </span>m_out[<span class="number">1</span>..] |
| } <span class="kw">else </span>{ |
| m_out |
| }; |
| <span class="macro">assert_eq!</span>(em.len(), metrics.em_len); |
| |
| <span class="comment">// Steps 1 and 2 are done by the caller to produce `m_hash`. |
| |
| // Step 3 is done by `PSSMetrics::new()` above. |
| |
| // Step 4. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>salt = [<span class="number">0u8</span>; MAX_SALT_LEN]; |
| <span class="kw">let </span>salt = <span class="kw-2">&mut </span>salt[..metrics.s_len]; |
| rng.fill(salt)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Step 5 and 6. |
| </span><span class="kw">let </span>h_hash = pss_digest(<span class="self">self</span>.digest_alg, m_hash, salt); |
| |
| <span class="comment">// Re-order steps 7, 8, 9 and 10 so that we first output the db mask |
| // into `em`, and then XOR the value of db. |
| |
| // Step 9. First output the mask into the out buffer. |
| </span><span class="kw">let </span>(<span class="kw-2">mut </span>masked_db, digest_terminator) = em.split_at_mut(metrics.db_len); |
| mgf1(<span class="self">self</span>.digest_alg, h_hash.as_ref(), <span class="kw-2">&mut </span>masked_db)<span class="question-mark">?</span>; |
| |
| { |
| <span class="comment">// Steps 7. |
| </span><span class="kw">let </span>masked_db = masked_db.iter_mut(); |
| <span class="comment">// `PS` is all zero bytes, so skipping `ps_len` bytes is equivalent |
| // to XORing `PS` onto `db`. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>masked_db = masked_db.skip(metrics.ps_len); |
| |
| <span class="comment">// Step 8. |
| </span><span class="kw-2">*</span>(masked_db.next().ok_or(error::Unspecified)<span class="question-mark">?</span>) ^= <span class="number">0x01</span>; |
| |
| <span class="comment">// Step 10. |
| </span><span class="kw">for </span>(masked_db_b, salt_b) <span class="kw">in </span>masked_db.zip(salt) { |
| <span class="kw-2">*</span>masked_db_b ^= <span class="kw-2">*</span>salt_b; |
| } |
| } |
| |
| <span class="comment">// Step 11. |
| </span>masked_db[<span class="number">0</span>] &= metrics.top_byte_mask; |
| |
| <span class="comment">// Step 12. |
| </span>digest_terminator[..metrics.h_len].copy_from_slice(h_hash.as_ref()); |
| digest_terminator[metrics.h_len] = <span class="number">0xbc</span>; |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="kw">impl </span>Verification <span class="kw">for </span>PSS { |
| <span class="comment">// RSASSA-PSS-VERIFY from https://tools.ietf.org/html/rfc3447#section-8.1.2 |
| // where steps 1, 2(a), and 2(b) have been done for us. |
| </span><span class="kw">fn </span>verify( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| m: <span class="kw-2">&mut </span>untrusted::Reader, |
| mod_bits: bits::BitLength, |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">let </span>metrics = PSSMetrics::new(<span class="self">self</span>.digest_alg, mod_bits)<span class="question-mark">?</span>; |
| |
| <span class="comment">// RSASSA-PSS-VERIFY Step 2(c). The `m` this function is given is the |
| // big-endian-encoded value of `m` from the specification, padded to |
| // `k` bytes, where `k` is the length in bytes of the public modulus. |
| // The spec. says "Note that emLen will be one less than k if |
| // modBits - 1 is divisible by 8 and equal to k otherwise," where `k` |
| // is the length in octets of the RSA public modulus `n`. In other |
| // words, `em` might have an extra leading zero byte that we need to |
| // strip before we start the PSS decoding steps which is an artifact of |
| // the `Verification` interface. |
| </span><span class="kw">if </span>metrics.top_byte_mask == <span class="number">0xff </span>{ |
| <span class="kw">if </span>m.read_byte()<span class="question-mark">? </span>!= <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| }; |
| <span class="kw">let </span>em = m; |
| |
| <span class="comment">// The rest of this function is EMSA-PSS-VERIFY from |
| // https://tools.ietf.org/html/rfc3447#section-9.1.2. |
| |
| // Steps 1 and 2 are done by the caller to produce `m_hash`. |
| |
| // Step 3 is done by `PSSMetrics::new()` above. |
| |
| // Step 5, out of order. |
| </span><span class="kw">let </span>masked_db = em.read_bytes(metrics.db_len)<span class="question-mark">?</span>; |
| <span class="kw">let </span>h_hash = em.read_bytes(metrics.h_len)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Step 4. |
| </span><span class="kw">if </span>em.read_byte()<span class="question-mark">? </span>!= <span class="number">0xbc </span>{ |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| |
| <span class="comment">// Step 7. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>db = [<span class="number">0u8</span>; PUBLIC_KEY_PUBLIC_MODULUS_MAX_LEN]; |
| <span class="kw">let </span>db = <span class="kw-2">&mut </span>db[..metrics.db_len]; |
| |
| mgf1(<span class="self">self</span>.digest_alg, h_hash.as_slice_less_safe(), db)<span class="question-mark">?</span>; |
| |
| masked_db.read_all(error::Unspecified, |masked_bytes| { |
| <span class="comment">// Step 6. Check the top bits of first byte are zero. |
| </span><span class="kw">let </span>b = masked_bytes.read_byte()<span class="question-mark">?</span>; |
| <span class="kw">if </span>b & !metrics.top_byte_mask != <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| db[<span class="number">0</span>] ^= b; |
| |
| <span class="comment">// Step 8. |
| </span><span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..db.len() { |
| db[i] ^= masked_bytes.read_byte()<span class="question-mark">?</span>; |
| } |
| <span class="prelude-val">Ok</span>(()) |
| })<span class="question-mark">?</span>; |
| |
| <span class="comment">// Step 9. |
| </span>db[<span class="number">0</span>] &= metrics.top_byte_mask; |
| |
| <span class="comment">// Step 10. |
| </span><span class="kw">let </span>ps_len = metrics.ps_len; |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..ps_len { |
| <span class="kw">if </span>db[i] != <span class="number">0 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| } |
| <span class="kw">if </span>db[metrics.ps_len] != <span class="number">1 </span>{ |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| |
| <span class="comment">// Step 11. |
| </span><span class="kw">let </span>salt = <span class="kw-2">&</span>db[(db.len() - metrics.s_len)..]; |
| |
| <span class="comment">// Step 12 and 13. |
| </span><span class="kw">let </span>h_prime = pss_digest(<span class="self">self</span>.digest_alg, m_hash, salt); |
| |
| <span class="comment">// Step 14. |
| </span><span class="kw">if </span>h_hash != <span class="kw-2">*</span>h_prime.as_ref() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(error::Unspecified); |
| } |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="kw">struct </span>PSSMetrics { |
| <span class="attribute">#[cfg_attr(not(feature = <span class="string">"alloc"</span>), allow(dead_code))] |
| </span>em_len: usize, |
| db_len: usize, |
| ps_len: usize, |
| s_len: usize, |
| h_len: usize, |
| top_byte_mask: u8, |
| } |
| |
| <span class="kw">impl </span>PSSMetrics { |
| <span class="kw">fn </span>new( |
| digest_alg: <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm, |
| mod_bits: bits::BitLength, |
| ) -> <span class="prelude-ty">Result</span><PSSMetrics, error::Unspecified> { |
| <span class="kw">let </span>em_bits = mod_bits.try_sub_1()<span class="question-mark">?</span>; |
| <span class="kw">let </span>em_len = em_bits.as_usize_bytes_rounded_up(); |
| <span class="kw">let </span>leading_zero_bits = (<span class="number">8 </span>* em_len) - em_bits.as_usize_bits(); |
| <span class="macro">debug_assert!</span>(leading_zero_bits < <span class="number">8</span>); |
| <span class="kw">let </span>top_byte_mask = <span class="number">0xffu8 </span>>> leading_zero_bits; |
| |
| <span class="kw">let </span>h_len = digest_alg.output_len; |
| |
| <span class="comment">// We require the salt length to be equal to the digest length. |
| </span><span class="kw">let </span>s_len = h_len; |
| |
| <span class="comment">// Step 3 of both `EMSA-PSS-ENCODE` is `EMSA-PSS-VERIFY` requires that |
| // we reject inputs where "emLen < hLen + sLen + 2". The definition of |
| // `emBits` in RFC 3447 Sections 9.1.1 and 9.1.2 says `emBits` must be |
| // "at least 8hLen + 8sLen + 9". Since 9 bits requires two bytes, these |
| // two conditions are equivalent. 9 bits are required as the 0x01 |
| // before the salt requires 1 bit and the 0xbc after the digest |
| // requires 8 bits. |
| </span><span class="kw">let </span>db_len = em_len.checked_sub(<span class="number">1 </span>+ s_len).ok_or(error::Unspecified)<span class="question-mark">?</span>; |
| <span class="kw">let </span>ps_len = db_len.checked_sub(h_len + <span class="number">1</span>).ok_or(error::Unspecified)<span class="question-mark">?</span>; |
| |
| <span class="macro">debug_assert!</span>(em_bits.as_usize_bits() >= (<span class="number">8 </span>* h_len) + (<span class="number">8 </span>* s_len) + <span class="number">9</span>); |
| |
| <span class="prelude-val">Ok</span>(PSSMetrics { |
| em_len, |
| db_len, |
| ps_len, |
| s_len, |
| h_len, |
| top_byte_mask, |
| }) |
| } |
| } |
| |
| <span class="comment">// Mask-generating function MGF1 as described in |
| // https://tools.ietf.org/html/rfc3447#appendix-B.2.1. |
| </span><span class="kw">fn </span>mgf1( |
| digest_alg: <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm, |
| seed: <span class="kw-2">&</span>[u8], |
| mask: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), error::Unspecified> { |
| <span class="kw">let </span>digest_len = digest_alg.output_len; |
| |
| <span class="comment">// Maximum counter value is the value of (mask_len / digest_len) rounded up. |
| </span><span class="kw">let </span>ctr_max = (mask.len() - <span class="number">1</span>) / digest_len; |
| <span class="macro">assert!</span>(ctr_max <= u32::max_value() <span class="kw">as </span>usize); |
| <span class="kw">for </span>(i, mask_chunk) <span class="kw">in </span>mask.chunks_mut(digest_len).enumerate() { |
| <span class="kw">let </span><span class="kw-2">mut </span>ctx = digest::Context::new(digest_alg); |
| ctx.update(seed); |
| ctx.update(<span class="kw-2">&</span>u32::to_be_bytes(i <span class="kw">as </span>u32)); |
| <span class="kw">let </span>digest = ctx.finish(); |
| <span class="kw">let </span>mask_chunk_len = mask_chunk.len(); |
| mask_chunk.copy_from_slice(<span class="kw-2">&</span>digest.as_ref()[..mask_chunk_len]); |
| } |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="kw">fn </span>pss_digest( |
| digest_alg: <span class="kw-2">&</span><span class="lifetime">'static </span>digest::Algorithm, |
| m_hash: <span class="kw-2">&</span>digest::Digest, |
| salt: <span class="kw-2">&</span>[u8], |
| ) -> digest::Digest { |
| <span class="comment">// Fixed prefix. |
| </span><span class="kw">const </span>PREFIX_ZEROS: [u8; <span class="number">8</span>] = [<span class="number">0u8</span>; <span class="number">8</span>]; |
| |
| <span class="comment">// Encoding step 5 and 6, Verification step 12 and 13. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>ctx = digest::Context::new(digest_alg); |
| ctx.update(<span class="kw-2">&</span>PREFIX_ZEROS); |
| ctx.update(m_hash.as_ref()); |
| ctx.update(salt); |
| ctx.finish() |
| } |
| |
| <span class="macro">macro_rules! </span>rsa_pss_padding { |
| ( <span class="macro-nonterminal">$PADDING_ALGORITHM</span>:ident, <span class="macro-nonterminal">$digest_alg</span>:expr, <span class="macro-nonterminal">$doc_str</span>:expr ) => { |
| <span class="attribute">#[doc=<span class="macro-nonterminal">$doc_str</span>] |
| </span><span class="kw">pub static </span><span class="macro-nonterminal">$PADDING_ALGORITHM</span>: PSS = PSS { |
| digest_alg: <span class="macro-nonterminal">$digest_alg</span>, |
| }; |
| }; |
| } |
| |
| <span class="macro">rsa_pss_padding!</span>( |
| RSA_PSS_SHA256, |
| <span class="kw-2">&</span>digest::SHA256, |
| <span class="string">"RSA PSS padding using SHA-256 for RSA signatures.\n\nSee |
| \"`RSA_PSS_*` Details\" in `ring::signature`'s module-level |
| documentation for more details." |
| </span>); |
| <span class="macro">rsa_pss_padding!</span>( |
| RSA_PSS_SHA384, |
| <span class="kw-2">&</span>digest::SHA384, |
| <span class="string">"RSA PSS padding using SHA-384 for RSA signatures.\n\nSee |
| \"`RSA_PSS_*` Details\" in `ring::signature`'s module-level |
| documentation for more details." |
| </span>); |
| <span class="macro">rsa_pss_padding!</span>( |
| RSA_PSS_SHA512, |
| <span class="kw-2">&</span>digest::SHA512, |
| <span class="string">"RSA PSS padding using SHA-512 for RSA signatures.\n\nSee |
| \"`RSA_PSS_*` Details\" in `ring::signature`'s module-level |
| documentation for more details." |
| </span>); |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>test { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use crate</span>::{digest, error, test}; |
| <span class="kw">use </span>alloc::vec; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_pss_padding_verify() { |
| test::run( |
| <span class="macro">test_file!</span>(<span class="string">"rsa_pss_padding_tests.txt"</span>), |
| |section, test_case| { |
| <span class="macro">assert_eq!</span>(section, <span class="string">""</span>); |
| |
| <span class="kw">let </span>digest_name = test_case.consume_string(<span class="string">"Digest"</span>); |
| <span class="kw">let </span>alg = <span class="kw">match </span>digest_name.as_ref() { |
| <span class="string">"SHA256" </span>=> <span class="kw-2">&</span>RSA_PSS_SHA256, |
| <span class="string">"SHA384" </span>=> <span class="kw-2">&</span>RSA_PSS_SHA384, |
| <span class="string">"SHA512" </span>=> <span class="kw-2">&</span>RSA_PSS_SHA512, |
| <span class="kw">_ </span>=> <span class="macro">panic!</span>(<span class="string">"Unsupported digest: {}"</span>, digest_name), |
| }; |
| |
| <span class="kw">let </span>msg = test_case.consume_bytes(<span class="string">"Msg"</span>); |
| <span class="kw">let </span>msg = untrusted::Input::from(<span class="kw-2">&</span>msg); |
| <span class="kw">let </span>m_hash = digest::digest(alg.digest_alg(), msg.as_slice_less_safe()); |
| |
| <span class="kw">let </span>encoded = test_case.consume_bytes(<span class="string">"EM"</span>); |
| <span class="kw">let </span>encoded = untrusted::Input::from(<span class="kw-2">&</span>encoded); |
| |
| <span class="comment">// Salt is recomputed in verification algorithm. |
| </span><span class="kw">let _ </span>= test_case.consume_bytes(<span class="string">"Salt"</span>); |
| |
| <span class="kw">let </span>bit_len = test_case.consume_usize_bits(<span class="string">"Len"</span>); |
| <span class="kw">let </span>is_valid = test_case.consume_string(<span class="string">"Result"</span>) == <span class="string">"P"</span>; |
| |
| <span class="kw">let </span>actual_result = |
| encoded.read_all(error::Unspecified, |m| alg.verify(<span class="kw-2">&</span>m_hash, m, bit_len)); |
| <span class="macro">assert_eq!</span>(actual_result.is_ok(), is_valid); |
| |
| <span class="prelude-val">Ok</span>(()) |
| }, |
| ); |
| } |
| |
| <span class="comment">// Tests PSS encoding for various public modulus lengths. |
| </span><span class="attribute">#[cfg(feature = <span class="string">"alloc"</span>)] |
| #[test] |
| </span><span class="kw">fn </span>test_pss_padding_encode() { |
| test::run( |
| <span class="macro">test_file!</span>(<span class="string">"rsa_pss_padding_tests.txt"</span>), |
| |section, test_case| { |
| <span class="macro">assert_eq!</span>(section, <span class="string">""</span>); |
| |
| <span class="kw">let </span>digest_name = test_case.consume_string(<span class="string">"Digest"</span>); |
| <span class="kw">let </span>alg = <span class="kw">match </span>digest_name.as_ref() { |
| <span class="string">"SHA256" </span>=> <span class="kw-2">&</span>RSA_PSS_SHA256, |
| <span class="string">"SHA384" </span>=> <span class="kw-2">&</span>RSA_PSS_SHA384, |
| <span class="string">"SHA512" </span>=> <span class="kw-2">&</span>RSA_PSS_SHA512, |
| <span class="kw">_ </span>=> <span class="macro">panic!</span>(<span class="string">"Unsupported digest: {}"</span>, digest_name), |
| }; |
| |
| <span class="kw">let </span>msg = test_case.consume_bytes(<span class="string">"Msg"</span>); |
| <span class="kw">let </span>salt = test_case.consume_bytes(<span class="string">"Salt"</span>); |
| <span class="kw">let </span>encoded = test_case.consume_bytes(<span class="string">"EM"</span>); |
| <span class="kw">let </span>bit_len = test_case.consume_usize_bits(<span class="string">"Len"</span>); |
| <span class="kw">let </span>expected_result = test_case.consume_string(<span class="string">"Result"</span>); |
| |
| <span class="comment">// Only test the valid outputs |
| </span><span class="kw">if </span>expected_result != <span class="string">"P" </span>{ |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(()); |
| } |
| |
| <span class="kw">let </span>rng = test::rand::FixedSliceRandom { bytes: <span class="kw-2">&</span>salt }; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>m_out = <span class="macro">vec!</span>[<span class="number">0u8</span>; bit_len.as_usize_bytes_rounded_up()]; |
| <span class="kw">let </span>digest = digest::digest(alg.digest_alg(), <span class="kw-2">&</span>msg); |
| alg.encode(<span class="kw-2">&</span>digest, <span class="kw-2">&mut </span>m_out, bit_len, <span class="kw-2">&</span>rng).unwrap(); |
| <span class="macro">assert_eq!</span>(m_out, encoded); |
| |
| <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> |
