fix(SSO): SAMLのメタデータに使われる証明書を保存するように

packages/backend/src/misc/gen-x509-cert-from-jwk.ts

@@ -0,0 +1,33 @@
+import forge from 'node-forge';
+import * as jose from 'jose';
+
+export async function genX509CertFromJWK(
+	hostname: string,
+	notBefore: Date,
+	notAfter: Date,
+	publicKey: string,
+	privateKey: string,
+): Promise<string> {
+	const cert = forge.pki.createCertificate();
+	cert.serialNumber = '01';
+	cert.validity.notBefore = notBefore;
+	cert.validity.notAfter = notAfter;
+
+	const attrs = [{ name: 'commonName', value: hostname }];
+	cert.setSubject(attrs);
+	cert.setIssuer(attrs);
+	cert.publicKey = await jose
+		.importJWK(JSON.parse(publicKey))
+		.then((k) => jose.exportSPKI(k as jose.KeyLike))
+		.then((k) => forge.pki.publicKeyFromPem(k));
+
+	cert.sign(
+		await jose
+			.importJWK(JSON.parse(privateKey))
+			.then((k) => jose.exportPKCS8(k as jose.KeyLike))
+			.then((k) => forge.pki.privateKeyFromPem(k)),
+		forge.md.sha256.create(),
+	);
+
+	return forge.pki.certificateToPem(cert);
+}