Crypto 101 – The basics of Cryptography – So, What is Crypto?

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Crypto 101 – The basics of Cryptography – So, What is Crypto?

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Crypto Presentation

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Crypto 101

The basics of Cryptography

Nootan Ghimire / @nootanghimire

So, What is Crypto?

Study of techniques for secure communication!

Oh hey, these are some notes. They'll be hidden in your presentation, but you can see them if you open the speaker notes window (hit 's' on your keyboard).

So, What is Crypto?

Something used to convert a message to nonsense!

Ask students if they have ever seen inside a computer's CPU. Ask them about different "components" that are present inside CPU, (ex. Power Supply, Processors, Bus, RAM) which are detachable. Next slide will present about examples to show why this approach is better.

Example!

The simplest Example would be: Ceaser Cipher!

The Ceaser Cipher!

converts: I LOVE YOU to

C FIPY SIO

When the Key is: 20

Okay, How does it work?

Each letter is shifted by the key!

Explain this. Suppose the key is One. And the message is ABCD Then after performing Ceaser Cipher, the message becomes BCDE. To Get it ba

To Get it Back

Just shift in opposite direction!

Explain What's happening here. You are using a same key to convert the message to nonsense, and the same key to get it back. Unless you have the key, You cannot decrypt

Cons!

One can sit all day and try all 26 combinations!

Tell, this technique is called brute-forcing. Trying all combinations until you get to the result. All crypto can be decrypted using brute force. The only problem is: Is it feasible/possible to brute force! Also Talk about Scytale (skiitaly), Steganography

Types of Encryption

  • Symmetric
  • Assymetric
  • Hybrid
The audience now knows about the keys used in encryption. Now, they can calssify according to the types

Symmetric

Use same key for encryption and Decryption Example: Ceaser Cipher!

Assymetric

It uses two different keys for encryption and decryption.

Which leads to:

Public Key Cryptography

Public Key Cryptography

Two Keys (A pair)

  • Public Key
  • Private Key
...

Public Key Cryptography

  • People Encrypt With Your Public Key!
  • You Decrypt that with your Private Key!

PGP

Pretty Good Privacy

PGP

is an Hybrid CryptoSystem.

...

So, GPG?

Is an free implementation of OpenPGP standard!

Demo Time!

Thank You!