How do SSL Certificates work?

SSL Certs

It’s all about really long prime numbers. We’re talking about numbers that have between 40 and 256 digits in them (binary digits for math nuts). There are two different prime numbers used:

  • One number is called the public key.
  • One number is called the private key.

Here’s how it works. Say you want people to send you their personal information securely. You tell them your private key and they scramble their information using the public key plus a special formula (or algorithm). They send you the scrambled information. You can then use your private key, plus the special formula, to decrypt the information.

So you can see that there is still information being sent over the internet. What is there to stop someone from intercepting the data and working out for themselves what the private key is?

In theory, nothing at all. In practice however, that’s why really long prime numbers are used. Here is how long it would take for a hacker today to work out the private key by trial and error, or brute force as it is called in the biz:

No of digits Time to decrypt by ‘brute force’
8 0 milliseconds
40 0.015 milliseconds
56 1 second
64 4 minutes, 16 seconds
128 149,745,258,842,898 years
256 50,955,671,114,250,072,156,962,268,275,658,377,807,020,642,877,435,085 years

So really the security is about the sheer number of combinations to guess. Experts suggest 128 bit security is ample for about the next ten years, until computers get quick enough to make it possible to maybe crack some codes. Many SSL providers now offer up to 256 bit certificates.

The SSL certificate that you install on your website contains not only your Public Key, but also a trusted Certificate Authority for your client’s web browser to check against (to make sure you are who you say you are, basically).

If you’d like to see our selection of SSL Certificates click here…

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Nick Miletic is a director of successful Australian web host company, Rack Servers. Nick has many years' experience in the web hosting industry and his peers consider him an authority on all things internet related.

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