What is csr?
A CSR (Certificate Signing Request) is a block of encoded text that a website or server creates when it wants to get an SSL/TLS certificate. It contains information like the domain name, organization details, and a public key, and it is sent to a Certificate Authority (CA) to prove who is requesting the certificate.
Let's break it down
- Key pair: First, the server generates a private key (kept secret) and a public key (shared).
- Info: The CSR includes the domain (e.g., example.com), company name, location, and the public key.
- Signature: The CSR is signed with the private key, proving the request really comes from the holder of that key.
- Send to CA: The CSR is uploaded to a Certificate Authority, which validates the info and issues a signed certificate.
Why does it matter?
A CSR is the first step in getting an SSL/TLS certificate, which encrypts data between a user’s browser and a website. Without it, the site can’t prove its identity, and visitors may see “Not secure” warnings, risking data theft and loss of trust.
Where is it used?
- Web servers (Apache, Nginx, IIS) when setting up HTTPS.
- Email servers that need secure connections.
- IoT devices that require encrypted communication.
- Any application that needs a public‑key certificate, such as VPNs or code‑signing tools.
Good things about it
- Security: Enables encrypted traffic, protecting passwords and personal data.
- Trust: Shows visitors that the site is verified by a reputable CA.
- Automation: Tools like Let’s Encrypt can generate and renew CSRs automatically.
- Portability: The same CSR can be used with different CAs if you change providers.
Not-so-good things
- Complexity for beginners: Generating keys and CSRs can be confusing without guidance.
- Private key risk: If the private key is lost or compromised, the certificate becomes useless or insecure.
- Expiration: Certificates (and the associated CSRs) need regular renewal, adding maintenance overhead.
- Cost: Some CAs charge for certificates, though free options exist.