Getting started with Cryptography and key concepts…

I hope to explain key concepts of cryptography and cryptology in this blog post. If you are interested in cryptography and looking for a start this would be helpful as this gives an overview about the cryptography.

Have you heard about cryptology? No. 😧

But you may have heard the word cryptography? Then cryptology is the place where the cryptography begins.

What is Cryptology?

“Cryptology is the mathematics, such as number theory, and the application of formulas and algorithms, that underpin cryptography and cryptanalysis.”

What is Cryptography?

In simple words, cryptography is secret writing. Secret writing to secure the texts.

“Cryptography is associated with the process of converting ordinary plain text into unintelligible text and vice-versa. It is a method of storing and transmitting data in a particular form so that only those for whom it is intended can read and process it.”

There is another important word which always goes with the cryptography. That is steganography.

What is Steganography?

While cryptography is secret writing, simple we can say that the steganography is hidden writing.

“Steganography is the hiding of a secret message within an ordinary message and the extraction of it at its destination. Steganography takes cryptography a step farther by hiding an encrypted message so that no one suspects it exists.”

Cryptography provides these qualities for transmitting data.

1. Confidentiality.
2. Integrity.
3. Availability.
4. Anonymity.
5. Non-repudiation of origin and delivery.
6. Contract signing.
7. Time stamping.
8. Key escrow.

Cryptography is not a new thing to the world. Cryptography has a legendary history on its’ way to the present. So cryptography can be divided into two classes.

1. Classical Cryptography.

• Based on the characters / alphabets.
• Secret writing is done by manually.

2. Modern Cryptography.

• Used with digital computer systems.
• Processes bits/bytes.

Look at the below diagram. It shows the distribution of the cryptography considering the history and the method of the cryptology.

• Classical cryptography can be categorized into two.

1. Confusion ( Substitution ) : letters are replaced with other letters.
2. Diffusion ( Transposition ) : the position of the letters are changed.

• Then these two are divided into two categories.

1. Monoalphabetic : This only considers one letter when replacing the letters.
2. Polyalphabetic : This considers a set of characters when replacing the letters.

• Modern cryptography can be categorized into two.

1. Symmetric : use one key for encryption and decryption.
2. Asymmetric : There is a key pair (private and public). Use public key for encryption and private key for decryption.

• Then these two are divided into two categories.

1. Stream Cipher : Consider only one bit at a time.
2. Block Cipher : Consider a block of bits at a time.

Hope this post would help you to get an basic understanding of cryptography .

Cheers :)