CA Certificate Without CSR: How To

TL;DR

Yes, a Certificate Authority (CA) can issue a certificate without a Certificate Signing Request (CSR), but it’s generally not recommended and often involves specific procedures or limitations. This is usually done for self-signed certificates or when the CA has alternative methods of verifying identity.

How to Issue a CA Certificate Without a CSR

1. Understand the Risks: Issuing a certificate without a CSR bypasses standard security checks. The private key isn’t generated and verified alongside the request, increasing the risk of compromise.
2. Self-Signed Certificates (Most Common): This is the easiest method.
   • You generate both the certificate and the private key on your own server.
   • No CA interaction is needed for the certificate itself, though you might use a CA to sign it later if desired.
   • Use OpenSSL:

     openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365

     This creates a self-signed certificate valid for 365 days. You’ll be prompted for information, but it doesn’t need to match official documentation.

3. CA-Specific Methods (Less Common): Some CAs offer ways to issue certificates without a traditional CSR.
   • Domain Control Validation (DCV) via DNS Records: The CA verifies you control the domain by checking for specific DNS records. This might allow certificate issuance without a full CSR, but it’s CA-dependent.
   • ACME Protocol: Automated Certificate Management Environment (ACME), used with tools like Certbot, can sometimes issue certificates without requiring a pre-existing CSR. It automates the validation process.

     certbot certonly --manual -d example.com

   • Direct Key Submission (Rare): A few CAs might allow you to submit your private key directly, but this is extremely risky and generally discouraged.
4. Steps for CA-Specific Methods:
   1. Check Your CA’s Documentation: The most important step! Each CA has different procedures.
   2. Follow the Validation Process: This usually involves adding DNS records, creating specific files on your web server, or using an email verification process.
   3. Submit the Request (if any): Some methods require submitting a request to the CA even without a CSR.
   4. Download and Install the Certificate: Once validated, download the certificate from the CA’s website.
5. Important Considerations:
   • Security: Certificates issued without proper CSR validation are less secure.
   • Browser Compatibility: Self-signed certificates will cause browser warnings unless explicitly trusted by the user.
   • Automation: ACME is the preferred method for automated certificate issuance and renewal, even if it requires some initial setup.