feat(server): add an embedded ACME directory server and certificate authority with challenge, order, and certificate endpoints

ts_server/server.classes.ca.ts

@@ -0,0 +1,142 @@
+import * as crypto from 'node:crypto';
+
+/**
+ * Certificate Authority for the ACME server.
+ * Generates a self-signed root CA and signs certificates from CSRs.
+ * Uses @peculiar/x509 (already a project dependency).
+ */
+export class AcmeServerCA {
+  private caKeyPair!: CryptoKeyPair;
+  private caCert!: InstanceType<typeof import('@peculiar/x509').X509Certificate>;
+  private caCertPem!: string;
+  private certValidityDays: number;
+
+  constructor(private options: { commonName?: string; validityDays?: number; certValidityDays?: number } = {}) {
+    this.certValidityDays = options.certValidityDays ?? 90;
+  }
+
+  async init(): Promise<void> {
+    const x509 = await import('@peculiar/x509');
+    const { webcrypto } = crypto;
+    x509.cryptoProvider.set(webcrypto as any);
+
+    // Generate RSA key pair for the CA
+    this.caKeyPair = await webcrypto.subtle.generateKey(
+      {
+        name: 'RSASSA-PKCS1-v1_5',
+        modulusLength: 2048,
+        publicExponent: new Uint8Array([1, 0, 1]),
+        hash: 'SHA-256',
+      },
+      true,
+      ['sign', 'verify'],
+    ) as CryptoKeyPair;
+
+    const cn = this.options.commonName ?? 'SmartACME Test CA';
+    const validityDays = this.options.validityDays ?? 3650;
+    const notBefore = new Date();
+    const notAfter = new Date();
+    notAfter.setDate(notAfter.getDate() + validityDays);
+
+    // Create self-signed root CA certificate
+    this.caCert = await x509.X509CertificateGenerator.createSelfSigned({
+      serialNumber: this.randomSerialNumber(),
+      name: `CN=${cn}`,
+      notBefore,
+      notAfter,
+      signingAlgorithm: { name: 'RSASSA-PKCS1-v1_5' },
+      keys: this.caKeyPair,
+      extensions: [
+        new x509.BasicConstraintsExtension(true, undefined, true),
+        new x509.KeyUsagesExtension(
+          x509.KeyUsageFlags.keyCertSign | x509.KeyUsageFlags.cRLSign,
+          true,
+        ),
+        await x509.SubjectKeyIdentifierExtension.create(this.caKeyPair.publicKey),
+      ],
+    });
+
+    this.caCertPem = this.caCert.toString('pem');
+  }
+
+  /**
+   * Sign a CSR and return a PEM certificate chain (end-entity + root CA).
+   * @param csrDerBase64url - The CSR in base64url-encoded DER format (as sent by ACME clients)
+   */
+  async signCsr(csrDerBase64url: string): Promise<string> {
+    const x509 = await import('@peculiar/x509');
+    const { webcrypto } = crypto;
+    x509.cryptoProvider.set(webcrypto as any);
+
+    // Parse the CSR
+    const csrDer = Buffer.from(csrDerBase64url, 'base64url');
+    const csr = new x509.Pkcs10CertificateRequest(csrDer);
+
+    // Extract Subject Alternative Names from CSR extensions
+    const sanNames: { type: 'dns'; value: string }[] = [];
+    const sanExt = csr.extensions?.find(
+      (ext) => ext.type === '2.5.29.17', // OID for SubjectAlternativeName
+    );
+
+    if (sanExt) {
+      const san = new x509.SubjectAlternativeNameExtension(sanExt.rawData);
+      if (san.names) {
+        const jsonNames = san.names.toJSON();
+        for (const name of jsonNames) {
+          if (name.type === 'dns') {
+            sanNames.push({ type: 'dns', value: name.value });
+          }
+        }
+      }
+    }
+
+    // If no SAN found, use CN from subject
+    if (sanNames.length === 0) {
+      const cnMatch = csr.subject.match(/CN=([^,]+)/);
+      if (cnMatch) {
+        sanNames.push({ type: 'dns', value: cnMatch[1] });
+      }
+    }
+
+    const notBefore = new Date();
+    const notAfter = new Date();
+    notAfter.setDate(notAfter.getDate() + this.certValidityDays);
+
+    // Sign the certificate
+    const cert = await x509.X509CertificateGenerator.create({
+      serialNumber: this.randomSerialNumber(),
+      subject: csr.subject,
+      issuer: this.caCert.subject,
+      notBefore,
+      notAfter,
+      signingAlgorithm: { name: 'RSASSA-PKCS1-v1_5' },
+      publicKey: csr.publicKey,
+      signingKey: this.caKeyPair.privateKey,
+      extensions: [
+        new x509.BasicConstraintsExtension(false, undefined, true),
+        new x509.KeyUsagesExtension(
+          x509.KeyUsageFlags.digitalSignature | x509.KeyUsageFlags.keyEncipherment,
+          true,
+        ),
+        new x509.ExtendedKeyUsageExtension(
+          ['1.3.6.1.5.5.7.3.1'], // serverAuth
+          true,
+        ),
+        new x509.SubjectAlternativeNameExtension(sanNames),
+        await x509.AuthorityKeyIdentifierExtension.create(this.caKeyPair.publicKey),
+      ],
+    });
+
+    // Return PEM chain: end-entity cert + root CA cert
+    const certPem = cert.toString('pem');
+    return `${certPem}\n${this.caCertPem}`;
+  }
+
+  getCaCertPem(): string {
+    return this.caCertPem;
+  }
+
+  private randomSerialNumber(): string {
+    return crypto.randomBytes(16).toString('hex');
+  }
+}