Security Fundamentals; Cryptography

What is Cryptography and why is it important?

Cryptography in it’s basic form is a method for obscuring things so they can not be discovered in transit.

The Caesar cipher – one of the most famous earliest forms of cryptography was used to prevent the armies messages from being intercepted and read. By shifting the alphabet by three,the message would hopefully make no sense to anyone who intercepted it on route.

Of course with the curtains and cloak pulled back it seems trivial. But at the time many of the enemies were illiterate and the message would have seemed very obscure, as if written in a foreign language.

This bears much resemblance to today’s security.  You can never make a device completely secure, but if you can make your security stronger than the attackers will, and obscure the methods of vulnerability enough to create an seemingly insurmountable task then you have a chance to maintain long term integrity of your network and devices.

Cryptography has come a long way since the Caesar Cipher and is widely used in today’s technology, especially with mobile phones or debit/credit card transactions.

Today’s cryptography is ever more rooted in math.

For public key encryption we begin by creating a cryptography hash function that turns a string of text into an arbitrary bit string ‘summary’ of the input and effectively creates a one way function, infeasible by today’s power to invert without knowing the basis for the hash.

There are a number of hash functions we can use, however over time many have proved to be vulnerable or suspect, for example SHA1 has no known collisions yet, however the way technology has evolved gives us reasonable evidence to suggest that it will become vulnerable at some point in the not too distant future, so mitigation to other hash functions (in the SHA family for example) is suggested.

Whilst there is far more to cryptography, and especially the fascinating math that goes into creating hashing algorithms, you now have a general idea of what cryptography is, and how it works.










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