rustls/crypto/
signer.rs

1use alloc::boxed::Box;
2use alloc::vec::Vec;
3use core::fmt::Debug;
4
5use pki_types::{AlgorithmIdentifier, CertificateDer, PrivateKeyDer, SubjectPublicKeyInfoDer};
6
7use super::CryptoProvider;
8use crate::client::ResolvesClientCert;
9use crate::enums::{SignatureAlgorithm, SignatureScheme};
10use crate::error::{Error, InconsistentKeys};
11use crate::server::{ClientHello, ParsedCertificate, ResolvesServerCert};
12use crate::sync::Arc;
13use crate::x509;
14
15/// An abstract signing key.
16///
17/// This interface is used by rustls to use a private signing key
18/// for authentication.  This includes server and client authentication.
19///
20/// Objects of this type are always used within Rustls as
21/// `Arc<dyn SigningKey>`. There are no concrete public structs in Rustls
22/// that implement this trait.
23///
24/// There are two main ways to get a signing key:
25///
26///  - [`KeyProvider::load_private_key()`], or
27///  - some other method outside of the `KeyProvider` extension trait,
28///    for instance:
29///    - [`crypto::ring::sign::any_ecdsa_type()`]
30///    - [`crypto::ring::sign::any_eddsa_type()`]
31///    - [`crypto::ring::sign::any_supported_type()`]
32///    - [`crypto::aws_lc_rs::sign::any_ecdsa_type()`]
33///    - [`crypto::aws_lc_rs::sign::any_eddsa_type()`]
34///    - [`crypto::aws_lc_rs::sign::any_supported_type()`]
35///
36/// The `KeyProvider` method `load_private_key()` is called under the hood by
37/// [`ConfigBuilder::with_single_cert()`],
38/// [`ConfigBuilder::with_client_auth_cert()`], and
39/// [`ConfigBuilder::with_single_cert_with_ocsp()`].
40///
41/// A signing key created outside of the `KeyProvider` extension trait can be used
42/// to create a [`CertifiedKey`], which in turn can be used to create a
43/// [`ResolvesServerCertUsingSni`]. Alternately, a `CertifiedKey` can be returned from a
44/// custom implementation of the [`ResolvesServerCert`] or [`ResolvesClientCert`] traits.
45///
46/// [`KeyProvider::load_private_key()`]: crate::crypto::KeyProvider::load_private_key
47/// [`ConfigBuilder::with_single_cert()`]: crate::ConfigBuilder::with_single_cert
48/// [`ConfigBuilder::with_single_cert_with_ocsp()`]: crate::ConfigBuilder::with_single_cert_with_ocsp
49/// [`ConfigBuilder::with_client_auth_cert()`]: crate::ConfigBuilder::with_client_auth_cert
50/// [`crypto::ring::sign::any_ecdsa_type()`]: crate::crypto::ring::sign::any_ecdsa_type
51/// [`crypto::ring::sign::any_eddsa_type()`]: crate::crypto::ring::sign::any_eddsa_type
52/// [`crypto::ring::sign::any_supported_type()`]: crate::crypto::ring::sign::any_supported_type
53/// [`crypto::aws_lc_rs::sign::any_ecdsa_type()`]: crate::crypto::aws_lc_rs::sign::any_ecdsa_type
54/// [`crypto::aws_lc_rs::sign::any_eddsa_type()`]: crate::crypto::aws_lc_rs::sign::any_eddsa_type
55/// [`crypto::aws_lc_rs::sign::any_supported_type()`]: crate::crypto::aws_lc_rs::sign::any_supported_type
56/// [`ResolvesServerCertUsingSni`]: crate::server::ResolvesServerCertUsingSni
57/// [`ResolvesServerCert`]: crate::server::ResolvesServerCert
58/// [`ResolvesClientCert`]: crate::client::ResolvesClientCert
59pub trait SigningKey: Debug + Send + Sync {
60    /// Choose a `SignatureScheme` from those offered.
61    ///
62    /// Expresses the choice by returning something that implements `Signer`,
63    /// using the chosen scheme.
64    fn choose_scheme(&self, offered: &[SignatureScheme]) -> Option<Box<dyn Signer>>;
65
66    /// Get the RFC 5280-compliant SubjectPublicKeyInfo (SPKI) of this [`SigningKey`].
67    ///
68    /// If an implementation does not have the ability to derive this,
69    /// it can return `None`.
70    fn public_key(&self) -> Option<SubjectPublicKeyInfoDer<'_>>;
71
72    /// What kind of key we have.
73    fn algorithm(&self) -> SignatureAlgorithm;
74}
75
76/// A thing that can sign a message.
77pub trait Signer: Debug + Send + Sync {
78    /// Signs `message` using the selected scheme.
79    ///
80    /// `message` is not hashed; the implementer must hash it using the hash function
81    /// implicit in [`Self::scheme()`].
82    ///
83    /// The returned signature format is also defined by [`Self::scheme()`].
84    fn sign(&self, message: &[u8]) -> Result<Vec<u8>, Error>;
85
86    /// Reveals which scheme will be used when you call [`Self::sign()`].
87    fn scheme(&self) -> SignatureScheme;
88}
89
90/// Server certificate resolver which always resolves to the same certificate and key.
91///
92/// For use with [`ConfigBuilder::with_cert_resolver()`].
93///
94/// [`ConfigBuilder::with_cert_resolver()`]: crate::ConfigBuilder::with_cert_resolver
95#[derive(Debug)]
96pub struct SingleCertAndKey(Arc<CertifiedKey>);
97
98impl From<CertifiedKey> for SingleCertAndKey {
99    fn from(certified_key: CertifiedKey) -> Self {
100        Self(Arc::new(certified_key))
101    }
102}
103
104impl From<Arc<CertifiedKey>> for SingleCertAndKey {
105    fn from(certified_key: Arc<CertifiedKey>) -> Self {
106        Self(certified_key)
107    }
108}
109
110impl ResolvesClientCert for SingleCertAndKey {
111    fn resolve(
112        &self,
113        _root_hint_subjects: &[&[u8]],
114        _sigschemes: &[SignatureScheme],
115    ) -> Option<Arc<CertifiedKey>> {
116        Some(self.0.clone())
117    }
118
119    fn has_certs(&self) -> bool {
120        true
121    }
122}
123
124impl ResolvesServerCert for SingleCertAndKey {
125    fn resolve(&self, _client_hello: &ClientHello<'_>) -> Option<Arc<CertifiedKey>> {
126        Some(self.0.clone())
127    }
128}
129
130/// A packaged-together certificate chain, matching `SigningKey` and
131/// optional stapled OCSP response.
132///
133/// Note: this struct is also used to represent an [RFC 7250] raw public key,
134/// when the client/server is configured to use raw public keys instead of
135/// certificates.
136///
137/// [RFC 7250]: https://tools.ietf.org/html/rfc7250
138#[derive(Clone, Debug)]
139pub struct CertifiedKey {
140    /// The certificate chain or raw public key.
141    pub cert: Vec<CertificateDer<'static>>,
142
143    /// The certified key.
144    pub key: Arc<dyn SigningKey>,
145
146    /// An optional OCSP response from the certificate issuer,
147    /// attesting to its continued validity.
148    pub ocsp: Option<Vec<u8>>,
149}
150
151impl CertifiedKey {
152    /// Create a new `CertifiedKey` from a certificate chain and DER-encoded private key.
153    ///
154    /// Attempt to parse the private key with the given [`CryptoProvider`]'s [`KeyProvider`] and
155    /// verify that it matches the public key in the first certificate of the `cert_chain`
156    /// if possible.
157    ///
158    /// [`KeyProvider`]: crate::crypto::KeyProvider
159    pub fn from_der(
160        cert_chain: Vec<CertificateDer<'static>>,
161        key: PrivateKeyDer<'static>,
162        provider: &CryptoProvider,
163    ) -> Result<Self, Error> {
164        let private_key = provider
165            .key_provider
166            .load_private_key(key)?;
167
168        let certified_key = Self::new(cert_chain, private_key);
169        match certified_key.keys_match() {
170            // Don't treat unknown consistency as an error
171            Ok(()) | Err(Error::InconsistentKeys(InconsistentKeys::Unknown)) => Ok(certified_key),
172            Err(err) => Err(err),
173        }
174    }
175
176    /// Make a new CertifiedKey, with the given chain and key.
177    ///
178    /// The cert chain must not be empty. The first certificate in the chain
179    /// must be the end-entity certificate.
180    pub fn new(cert: Vec<CertificateDer<'static>>, key: Arc<dyn SigningKey>) -> Self {
181        Self {
182            cert,
183            key,
184            ocsp: None,
185        }
186    }
187
188    /// Verify the consistency of this [`CertifiedKey`]'s public and private keys.
189    /// This is done by performing a comparison of SubjectPublicKeyInfo bytes.
190    pub fn keys_match(&self) -> Result<(), Error> {
191        let Some(key_spki) = self.key.public_key() else {
192            return Err(InconsistentKeys::Unknown.into());
193        };
194
195        let cert = ParsedCertificate::try_from(self.end_entity_cert()?)?;
196        match key_spki == cert.subject_public_key_info() {
197            true => Ok(()),
198            false => Err(InconsistentKeys::KeyMismatch.into()),
199        }
200    }
201
202    /// The end-entity certificate.
203    pub fn end_entity_cert(&self) -> Result<&CertificateDer<'_>, Error> {
204        self.cert
205            .first()
206            .ok_or(Error::NoCertificatesPresented)
207    }
208}
209
210#[cfg_attr(not(any(feature = "aws-lc-rs", feature = "ring")), allow(dead_code))]
211pub(crate) fn public_key_to_spki(
212    alg_id: &AlgorithmIdentifier,
213    public_key: impl AsRef<[u8]>,
214) -> SubjectPublicKeyInfoDer<'static> {
215    // SubjectPublicKeyInfo  ::=  SEQUENCE  {
216    //    algorithm            AlgorithmIdentifier,
217    //    subjectPublicKey     BIT STRING  }
218    //
219    // AlgorithmIdentifier  ::=  SEQUENCE  {
220    //    algorithm               OBJECT IDENTIFIER,
221    //    parameters              ANY DEFINED BY algorithm OPTIONAL  }
222    //
223    // note that the `pki_types::AlgorithmIdentifier` type is the
224    // concatenation of `algorithm` and `parameters`, but misses the
225    // outer `Sequence`.
226
227    let mut spki_inner = x509::wrap_in_sequence(alg_id.as_ref());
228    spki_inner.extend(&x509::wrap_in_bit_string(public_key.as_ref()));
229
230    let spki = x509::wrap_in_sequence(&spki_inner);
231
232    SubjectPublicKeyInfoDer::from(spki)
233}
rustls/crypto/signer.rs

rustls/crypto/
signer.rs
