Understanding Cryptography

What is cryptography?

  • The science of transforming intelligible data into unintelligible data and retransforming that into its original form.
  • It provides confidentiality, integrity, & accuracy.

Encryption & Decryption

Encryption

  • The process of converting intelligible (plain) data to unintelligible (cipher) data.

Decryption

  • The process of converting cipher text to plain text

Types of Cryptography

Symmetric Key Cryptography

  • Same key used by both parties.
  • Advantage: Simpler & Faster
  • Disadvantage: Less secured

Asymmetric Key Cryptography

  • Different key is used by both parties
  • Key is issued by a certificate authority
  • Advantage: More secured
  • Disadvantage: Relatively complex

Some examples

Let's consider Abhishek & Suman

  • Abhishek buys a couple of padlocks which can be opened using a single key.
  • Now Abhishek distributes the padlock among his friends.
  • Whenever Suman wants to send something to Abhishek, he put it in a box and lock it with the padlock.
  • That's an example of Symmetric Key Cryptography!

How asymmetric encryption works

  • Abhishek generates two keys together, a public key, and a private key.
  • The same is done by Suman.
  • Abhishek & Suman, both will share their public keys with each other to encrypt messages.
  • Private key will be kept secret by both, for decrypting message.

What is a key?

  • A variable that is applied using an algorithm to a string of unencrypted text to produce encrypted text and vice-versa.
  • The length of the key depends on the difficulty level of encryption.

What is DES (Data Encryption Standards)

  • The most popular symmetric-key systems.
  • DES uses 56-bit keys, which is small enough to easily get brute forced by modern hardware.
  • 3DES uses 128-bit keys. The same algorithm is applied three times to produce a stronger key.

What is AES (Advanced Encryption Standards)

  • Also known as Rijndael
  • Key's block size is 128-bit but length can be 128, 192 & 256 bits.
  • Faster & more ​secure than 3DES.

That's it.

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