fix(bootstrap): emit RFC 5280 extensions on generated gateway PKI

crates/openshell-bootstrap/Cargo.toml

@@ -22,6 +22,7 @@ tokio = { workspace = true }
 tracing = { workspace = true }
 
 [dev-dependencies]
+x509-parser = "0.16"
 
 [lints]
 workspace = true

crates/openshell-bootstrap/src/pki.rs

@@ -3,7 +3,9 @@
 
 use crate::jwt::{JwtKeyMaterial, generate_jwt_key};
 use miette::{IntoDiagnostic, Result, WrapErr};
-use rcgen::{BasicConstraints, CertificateParams, DnType, Ia5String, IsCa, KeyPair, SanType};
+use rcgen::{
+    BasicConstraints, CertificateParams, DnType, Ia5String, IsCa, KeyPair, KeyUsagePurpose, SanType,
+};
 use std::net::IpAddr;
 
 /// All PEM-encoded materials produced by [`generate_pki`].
@@ -59,6 +61,7 @@ pub fn generate_pki(extra_sans: &[String]) -> Result<PkiBundle> {
         .into_diagnostic()
         .wrap_err("failed to create CA params")?;
     ca_params.is_ca = IsCa::Ca(BasicConstraints::Unconstrained);
+    ca_params.key_usages = vec![KeyUsagePurpose::KeyCertSign, KeyUsagePurpose::CrlSign];
     ca_params
         .distinguished_name
         .push(DnType::OrganizationName, "openshell");
@@ -80,6 +83,7 @@ pub fn generate_pki(extra_sans: &[String]) -> Result<PkiBundle> {
         .into_diagnostic()
         .wrap_err("failed to create server cert params")?;
     server_params.subject_alt_names = server_sans;
+    server_params.use_authority_key_identifier_extension = true;
     server_params
         .distinguished_name
         .push(DnType::CommonName, "openshell-server");
@@ -96,6 +100,7 @@ pub fn generate_pki(extra_sans: &[String]) -> Result<PkiBundle> {
     let mut client_params = CertificateParams::new(Vec::<String>::new())
         .into_diagnostic()
         .wrap_err("failed to create client cert params")?;
+    client_params.use_authority_key_identifier_extension = true;
     client_params
         .distinguished_name
         .push(DnType::CommonName, "openshell-client");
@@ -178,6 +183,58 @@ mod tests {
         assert!(bundle.server_cert_pem.contains("BEGIN CERTIFICATE"));
     }
 
+    #[test]
+    fn generate_pki_emits_strict_verifier_extensions() {
+        use x509_parser::pem::parse_x509_pem;
+        use x509_parser::prelude::{FromDer, ParsedExtension, X509Certificate};
+
+        let bundle = generate_pki(&[]).expect("generate_pki failed");
+        let parse = |pem: &str| -> Vec<u8> {
+            parse_x509_pem(pem.as_bytes())
+                .expect("valid PEM")
+                .1
+                .contents
+        };
+        let ca_der = parse(&bundle.ca_cert_pem);
+        let ca = X509Certificate::from_der(&ca_der).expect("valid CA cert").1;
+        let ca_key_usage = ca
+            .key_usage()
+            .expect("readable key usage")
+            .expect("CA has a key usage extension");
+        assert!(ca_key_usage.value.key_cert_sign());
+        assert!(ca_key_usage.value.crl_sign());
+        let ca_ski = ca
+            .get_extension_unique(&x509_parser::oid_registry::OID_X509_EXT_SUBJECT_KEY_IDENTIFIER)
+            .expect("readable SKI")
+            .expect("CA has a Subject Key Identifier");
+
+        for (name, pem) in [
+            ("server", &bundle.server_cert_pem),
+            ("client", &bundle.client_cert_pem),
+        ] {
+            let der = parse(pem);
+            let cert = X509Certificate::from_der(&der).expect("valid leaf cert").1;
+            let aki = cert
+                .get_extension_unique(
+                    &x509_parser::oid_registry::OID_X509_EXT_AUTHORITY_KEY_IDENTIFIER,
+                )
+                .expect("readable AKI")
+                .unwrap_or_else(|| panic!("{name} cert has no Authority Key Identifier"));
+            let (
+                ParsedExtension::AuthorityKeyIdentifier(aki),
+                ParsedExtension::SubjectKeyIdentifier(ski),
+            ) = (aki.parsed_extension(), ca_ski.parsed_extension())
+            else {
+                panic!("{name}: unexpected extension shapes");
+            };
+            let key_id = aki
+                .key_identifier
+                .as_ref()
+                .unwrap_or_else(|| panic!("{name} AKI has no key identifier"));
+            assert_eq!(key_id.0, ski.0, "{name} AKI must match the CA SKI");
+        }
+    }
+
     #[test]
     fn build_server_sans_includes_defaults_and_extras() {
         let extras = vec!["192.168.1.100".to_string(), "remote.host".to_string()];