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use alloc::boxed::Box;
use alloc::sync::Arc;
use alloc::vec::Vec;
use core::fmt::Debug;
use pki_types::{AlgorithmIdentifier, CertificateDer, SubjectPublicKeyInfoDer};
use crate::enums::{SignatureAlgorithm, SignatureScheme};
use crate::error::{Error, InconsistentKeys};
use crate::server::ParsedCertificate;
use crate::x509;
/// An abstract signing key.
///
/// This interface is used by rustls to use a private signing key
/// for authentication. This includes server and client authentication.
///
/// Objects of this type are always used within Rustls as
/// `Arc<dyn SigningKey>`. There are no concrete public structs in Rustls
/// that implement this trait.
///
/// There are two main ways to get a signing key:
///
/// - [`KeyProvider::load_private_key()`], or
/// - some other method outside of the `KeyProvider` extension trait,
/// for instance:
/// - [`crypto::ring::sign::any_ecdsa_type()`]
/// - [`crypto::ring::sign::any_eddsa_type()`]
/// - [`crypto::ring::sign::any_supported_type()`]
/// - [`crypto::aws_lc_rs::sign::any_ecdsa_type()`]
/// - [`crypto::aws_lc_rs::sign::any_eddsa_type()`]
/// - [`crypto::aws_lc_rs::sign::any_supported_type()`]
///
/// The `KeyProvider` method `load_private_key()` is called under the hood by
/// [`ConfigBuilder::with_single_cert()`],
/// [`ConfigBuilder::with_client_auth_cert()`], and
/// [`ConfigBuilder::with_single_cert_with_ocsp()`].
///
/// A signing key created outside of the `KeyProvider` extension trait can be used
/// to create a [`CertifiedKey`], which in turn can be used to create a
/// [`ResolvesServerCertUsingSni`]. Alternately, a `CertifiedKey` can be returned from a
/// custom implementation of the [`ResolvesServerCert`] or [`ResolvesClientCert`] traits.
///
/// [`KeyProvider::load_private_key()`]: crate::crypto::KeyProvider::load_private_key
/// [`ConfigBuilder::with_single_cert()`]: crate::ConfigBuilder::with_single_cert
/// [`ConfigBuilder::with_single_cert_with_ocsp()`]: crate::ConfigBuilder::with_single_cert_with_ocsp
/// [`ConfigBuilder::with_client_auth_cert()`]: crate::ConfigBuilder::with_client_auth_cert
/// [`crypto::ring::sign::any_ecdsa_type()`]: crate::crypto::ring::sign::any_ecdsa_type
/// [`crypto::ring::sign::any_eddsa_type()`]: crate::crypto::ring::sign::any_eddsa_type
/// [`crypto::ring::sign::any_supported_type()`]: crate::crypto::ring::sign::any_supported_type
/// [`crypto::aws_lc_rs::sign::any_ecdsa_type()`]: crate::crypto::aws_lc_rs::sign::any_ecdsa_type
/// [`crypto::aws_lc_rs::sign::any_eddsa_type()`]: crate::crypto::aws_lc_rs::sign::any_eddsa_type
/// [`crypto::aws_lc_rs::sign::any_supported_type()`]: crate::crypto::aws_lc_rs::sign::any_supported_type
/// [`ResolvesServerCertUsingSni`]: crate::server::ResolvesServerCertUsingSni
/// [`ResolvesServerCert`]: crate::server::ResolvesServerCert
/// [`ResolvesClientCert`]: crate::client::ResolvesClientCert
pub trait SigningKey: Debug + Send + Sync {
/// Choose a `SignatureScheme` from those offered.
///
/// Expresses the choice by returning something that implements `Signer`,
/// using the chosen scheme.
fn choose_scheme(&self, offered: &[SignatureScheme]) -> Option<Box<dyn Signer>>;
/// Get the RFC 5280-compliant SubjectPublicKeyInfo (SPKI) of this [`SigningKey`] if available.
fn public_key(&self) -> Option<SubjectPublicKeyInfoDer<'_>> {
// Opt-out by default
None
}
/// What kind of key we have.
fn algorithm(&self) -> SignatureAlgorithm;
}
/// A thing that can sign a message.
pub trait Signer: Debug + Send + Sync {
/// Signs `message` using the selected scheme.
///
/// `message` is not hashed; the implementer must hash it using the hash function
/// implicit in [`Self::scheme()`].
///
/// The returned signature format is also defined by [`Self::scheme()`].
fn sign(&self, message: &[u8]) -> Result<Vec<u8>, Error>;
/// Reveals which scheme will be used when you call [`Self::sign()`].
fn scheme(&self) -> SignatureScheme;
}
/// A packaged-together certificate chain, matching `SigningKey` and
/// optional stapled OCSP response.
#[derive(Clone, Debug)]
pub struct CertifiedKey {
/// The certificate chain.
pub cert: Vec<CertificateDer<'static>>,
/// The certified key.
pub key: Arc<dyn SigningKey>,
/// An optional OCSP response from the certificate issuer,
/// attesting to its continued validity.
pub ocsp: Option<Vec<u8>>,
}
impl CertifiedKey {
/// Make a new CertifiedKey, with the given chain and key.
///
/// The cert chain must not be empty. The first certificate in the chain
/// must be the end-entity certificate.
pub fn new(cert: Vec<CertificateDer<'static>>, key: Arc<dyn SigningKey>) -> Self {
Self {
cert,
key,
ocsp: None,
}
}
/// Verify the consistency of this [`CertifiedKey`]'s public and private keys.
/// This is done by performing a comparison of SubjectPublicKeyInfo bytes.
pub fn keys_match(&self) -> Result<(), Error> {
let key_spki = match self.key.public_key() {
Some(key) => key,
None => return Err(InconsistentKeys::Unknown.into()),
};
let cert = ParsedCertificate::try_from(self.end_entity_cert()?)?;
match key_spki == cert.subject_public_key_info() {
true => Ok(()),
false => Err(InconsistentKeys::KeyMismatch.into()),
}
}
/// The end-entity certificate.
pub fn end_entity_cert(&self) -> Result<&CertificateDer<'_>, Error> {
self.cert
.first()
.ok_or(Error::NoCertificatesPresented)
}
}
#[cfg_attr(not(any(feature = "aws_lc_rs", feature = "ring")), allow(dead_code))]
pub(crate) fn public_key_to_spki(
alg_id: &AlgorithmIdentifier,
public_key: impl AsRef<[u8]>,
) -> SubjectPublicKeyInfoDer<'static> {
// SubjectPublicKeyInfo ::= SEQUENCE {
// algorithm AlgorithmIdentifier,
// subjectPublicKey BIT STRING }
//
// AlgorithmIdentifier ::= SEQUENCE {
// algorithm OBJECT IDENTIFIER,
// parameters ANY DEFINED BY algorithm OPTIONAL }
//
// note that the `pki_types::AlgorithmIdentifier` type is the
// concatenation of `algorithm` and `parameters`, but misses the
// outer `Sequence`.
let mut spki_inner = x509::wrap_in_sequence(alg_id.as_ref());
spki_inner.extend(&x509::wrap_in_bit_string(public_key.as_ref()));
let spki = x509::wrap_in_sequence(&spki_inner);
SubjectPublicKeyInfoDer::from(spki)
}