Cryptography – Before & After Public Key.

What better way to kick off an Information Security blog than with a video from the computer history museum on Cryptography?  Whitefield Diffie is the speaker in this hour long presentation on cryptography history and is also one half of the Diffie Hellman duo who claim to have engineered this new approach.  The same claim comes from GCHQ in the United Kingdom and the two research finding were published a matter of months apart.

Public Key cryptography is implemented by generating a pair of keys (numbers) which are mathematically linked. One is deemed the “Public Key” which is available to all and the other is the “Private Key” which is held by the intended recipient of the information which will be encrypted.

The Public key is used to Encrypt and the Private Key is used to Decrypt. The Private Key can also be used in digital signing operations where the recipient can use the corresponding Public Key to verify the signature applied to a piece of information. Eloquently described by are long bearded and grey haired expert.


And if you would like to see a 3 minute summary of Public Key Cryptography at a high level, this video pretty much sums it up: