What is Cryptography? A Beginners Guide to Cryptographic Algorithms

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Many of us used coded or secret language in school that only we and our peers could understand keeping our conversation secret from others. What if we intended to encrypt business secrets, personal communications, and information? Here, cryptography plays an important role to maintain confidentiality, prevent unauthorised entry and guard against identity theft. In this blog, let’s discuss “what is Cryptography” and how cryptographic algorithms work in data encryption.

Using the example below, we can better comprehend “what is cryptography”.

Let’s pretend that you and I are business associates and we are communicating about our business deals via the open platform WhatsApp. We need our communication to be private, but the outcome would be undesirable if some adversaries overheard it. Here cryptographic algorithms play an important role in overcoming this data theft.

What is cryptography?

The Greek word “Kryptos,” which means “hidden,” is the source of the word “cryptography”.The study and practice of strategies for securing communication and data in the presence of adversaries is known as cryptography.

Encryption algorithms change plain text into ciphertext, an unreadable form. On the other hand, the Key decrypt the message and converts ciphertext to plain and understandable text.

What is a cryptographic algorithm?

A mathematical or computational procedure for converting the plain text to the ciphertext in a cryptographic system.

Following are the basic terms often used in cryptography.

Plain text– A message in its original form which is readable at the time of sending and receiving.

Cipher text- A meaningless, unreadable message which protects the data by converting it into numbers, symbols, characters, etc.,

Encryption-The process of altering the readable plain text to cipher text.

Key-A series of characters or numbers are employed in a cryptographic technique to encrypt and decrypt the data, much like a physical key to lock and unlock a door.

Now we got an idea about What is cryptography and its importance.

Based on the encryption algorithm and type of key used, cryptography can be classified into the following types.

Symmetric key cryptography
Asymmetric key cryptography

Symmetric key cryptography

If the key used for both the encryption and decryption of the data is the same then it is called symmetric cryptography. It is also called secret-key, single-key and private-key cryptography. It uses a single key, making the transport of vast volumes of data faster possible.

Examples of symmetric cryptography:

AES
DES
3DES
IDEA (International Data Encryption Algorithm)
Blowfish (Drop-in replacement for DES or IDEA)

Encryption of credit cards in banking can be taken as a real-time example of symmetric cryptography.

Symmetric key encryption has the fundamental drawback that it isn’t always practical for all participants to exchange the key that was used to encrypt the data before they can decrypt it.

Symmetric key cryptography can be classified into two types –Classic and Modern.

Modern cryptography is concerned with the careful study of any system that should defy malevolent attempts to abuse it, whereas classical cryptography was restricted to the skill of inventing and breaking encryption methods (or “secrecy codes”).

Classic cryptography can be categorised as follows

Transposition cipher.
Substitution cipher.

Transposition cipher

Transposition-based encryption scrambles character positions without altering the actual characters. It is also called a permutation cipher as the plain text is permutated to form cipher text.

Substitution cipher

In a cryptographic algorithm, if the characters of the plain text are substituted by numbers or different letters to produce cipher text, it is called a Substitution cipher.

Modern cryptography can be divided as follows,

Block cipher
Stream cipher

Block Cipher

As the name indicates it converts data into blocks and encrypts one block at a time. The newly available algorithms use blocks of 128 bits. The following modes of operation are available for block ciphers.

Counter mode(CTR)
Output Feedback mode(OFB)
Electronic Codebook (ECB)
Cipher Block Chaining (CBC)
Cipher Feedback (CFB)

Stream cipher

A type of encryption technology where byte by byte transformation of plain text is performed is Stream cipher. Without a proper key, cracking those unreadable cipher text becomes difficult. A stream cipher is safer comparing a block cipher.

Asymmetric key cryptography

Also known as public key cryptography. In this cryptographic technique, pair of keys is used which is created using a cryptographic algorithm and are connected mathematically. One is the private key and the other is the public key for the encryption and decryption of data or text. One needs a private key to decrypt the text which is encrypted using the private key.

Examples of Asymmetric cryptography:

Digital Signature Algorithm (DSA)
Elliptical Curve Cryptography (ECC)
the Diffie-Hellman exchange method.
TLS/SSL protocol.
Rivest Shamir Adleman (RSA)

Email and WhatsApp are real-time examples of asymmetric key cryptography. In email and WhatsApp, anyone can send a message or an email using the public key. Whereas, only with the private key the message or email can be deciphered.

The disadvantage of Asymmetric cryptography is:

It is a slow process
The private key is very important. If it is lost, the message cannot be decrypted.
There is no assurance for the authentication of the public key.

Asymmetric and symmetric key cryptography differ from one another in the following ways.

S.No	Symmetric key cryptography	Asymmetric key cryptography
1.	Encryption and decryption both are performed by a single key.	Uses a pair of keys (public and private). The public key is for encryption and the private key is for the decryption of messages.
2.	It is an old practice.	Relatively new.
3.	Key has to be shared among the individuals to share the data.	Since pair of keys is used, the problem of sharing keys is eliminated.
4.	The process is Faster.	Slow process.
5.	Implementation is complicated.	Much simpler.
6.	If the key is lost, there is a risk of losing the data	No need to compromise the data even if the public key is lost.
7.	More secure.	Less secure.

Conclusion

So, We understood ”What is cryptography” and how it helps in securing our data from unwanted threats. In addition to that, we also know how cryptographic algorithms play a major role in the internet world where every piece of information is to be secured.

As studying cryptography ensures a good career, Henry Harvin assists you in achieving that by offering a cyber security course.

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