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TLS server certificates

How to get TLS certificates for use within the University of Cambridge

What is TLS?

Transport Layer Security (TLS) is a way of securing Internet communications. TLS requires that the server (typically a web server) end of any communication has access to a public/private key pair and a cryptographic certificate linking these keys to the server's identity and to that of its operators. TLS replaced the now-deprecated SSL protocol, but the term SSL is still in everyday use. Many people and devices refer to TLS and SSL interchangeably.

For general use, you need to obtain TLS certificates from a widely trusted source, known as a Certification Authority or CA. The operating systems on computers maintain a list of trusted certificates which help them identify if the certificates they encounter are genuine.

For local use only, it is possible to create a "self-signed certificate" to secure local connections.

How to get a TLS certificate

Free DV certificates from Let's Encrypt

The Information Services Committee (ISC) advocates the use of zero-cost certificates from Let's Encrypt unless enhanced features or network configurations do not allow this. UIS uses and recommends using Let's Encrypt certificates wherever possible.

Let's Encrypt was established by the Internet Security Research Group (ISRG), and is supported by organisations and companies that want a more secure web. Let's Encrypt provides free automated Domain Validation (DV).

The easiest way to get started is to use certbot, a project of the Electronic Freedom Foundation.  

Your website needs to satisfy the following requirements to use certbot,:

    • is visible from outside the CUDN
    • is already online
    • with an open port 80
    • is hosted on a server that you can access with ssh
    • you can sudo on the server.

Once installed, certbot will install your Let's Encrypt certificate correctly and renew it automatically.

OV and EV certificates from Jisc

You can also purchase OV, EV and wildcard certificates from Jisc via our online ordering system. The costs incurred will be re-charged to your institution. You'll need to provide an institutional account code when you complete your order.

The prices are as follows:

Certificate type



Organisation Validation (OV) 1 year £20
Extended Validation (EV) 1 year £20
Wildcard certificate 1 year £150


Is it worth getting an Extended Validation (EV) certificate?

Web browsers no longer treat EV certificates more favourably than OV certificates, so there is no longer any advantage at all in using them.


Last updated: 17 February 2021