I have had interest in cryptography, and have lightly scratched the top of its surface many times in the past. So, I thought I'd be a bit more focussed and do something this time (the inspiration to do this again, probably came from reading Digital Fortress - note, I do realize it does not describe the most sophisticated/complex theories, never the less, it was entertaining
).Source for the info below: An Introduction to Cryptography
The Basics
As most would realize encryption is the process of "coding" some plain text message into some unreadable 'cipher text'. This cipher text is the encrypted message, this is then decrypted back to get the plan text message.
Symmetric Cipher
It means that the "key" used for encryption is the same as the key used for decryption
Asymmetric Cryptography (Public-key Cryptography)
It means the key for encryption and decryption are not the same. In public key cryptography, you publish your encryption key to the public. Anyone can use this information to send encrypted messaged to you. But you hold the private key which you would use to decrypt the message.
The good thing about this setup is the need to share the key between the sender and receiver is eliminated. All communication involve the public key, and no private key is ever transmitted or shared - I guess what this means is there is no longer a need to ensure a secure medium of transmission, any public infrastructure would satisfy.
As you may realize, keys are what create a specific cipher text for a given plain text. Generally, the size of the key is a good indicator of the security of the text. Of course, it also depends on the algorithm (more so).
One interesting thing is, public key cryptography key size and conventional cryptography key size are unrelated. A 80 bit conventional key has the equivalent strength of a 1024 bit public key
With that I'll end this session of AONTW!
Wish everyone a happy work week
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