# What is a Cipher? Types of Ciphers in Cryptography

Contents

As Caesar cipher and a modified version of Caesar cipher is easy to break, monoalphabetic cipher comes into the picture. In monoalphabetic, each alphabet in plain text can be replaced by any other alphabet except the original alphabet. That is, A can be replaced by any other alphabet from B to Z. B can be replaced by A or C to Z. C can be replaced by A, B, and D to Z, etc. Mono alphabetic cipher causes difficulty in cracking the message as there are random substitutions and a large number of permutations and combinations are available.

## Types of Cipher

In the world of digital fraud, to prevent our data, many techniques are useful to keep our data safe from hackers or any third party. In this article, we are going to discuss the types of cipher. Before that, let’s first see the meaning. Plain text is a message or data that can be readable by the sender, receiver, or any third party. When the plain text is modified by using some algorithms or techniques, the resulting data or message is called ciphertext. In short, converting plain text, i.e., readable text, into non-readable text is called ciphertext.

### Types of Cipher

Several types of cipher are given as follows:

#### 1. Caesar Cipher

In Caesar cipher, the set of plain text characters is replaced by any other character, symbols, or numbers. It is a very weak technique for hiding text. In Caesar’s cipher, each alphabet in the message is replaced by three places down. Let’s see one example. The plain text is EDUCBA. As a Caesar cipher, each alphabet is replaced by three places down. So that E will be replaced by H, D will be replaced by G, U will be replaced by X, C will be replaced by F, B will be replaced by E, and A will be replaced by D. So here, the plain text is EDUCBA and ciphertext Is HGXFED.

Caesar cipher algorithm is as follows:

- Read each alphabet of plain text.
- Replace each alphabet with 3 places down.
- Repeat the process for all alphabet in plain text.

**A Modified Version of Caesar Cipher:** This cipher works the same as Caesar cipher; the only difference is – in Caesar cipher, each alphabet is replaced by three-place down, wherein in a modified version of Caesar cipher, a user decides the number to replace the alphabet, and this number will be constant. For example, in EDUCBA, the number for the replacement is 1, so E will be replaced by F, D will be replaced by E, U will be replaced by V, C will be replaced by D, B will be replaced by C, and A will be replaced by B. So here, the plain text is EDUCBA, and the ciphertext Is FEVDCB.

A modified version of the Caesar cipher algorithm is as follows.

- Read each alphabet of plain text.
- Take the number for replacement.
- Replace each alphabet with a specified number down.
- Repeat the process for all alphabet in plain text.

#### 2. Monoalphabetic Cipher

As Caesar cipher and a modified version of Caesar cipher is easy to break, monoalphabetic cipher comes into the picture. In monoalphabetic, each alphabet in plain text can be replaced by any other alphabet except the original alphabet. That is, A can be replaced by any other alphabet from B to Z. B can be replaced by A or C to Z. C can be replaced by A, B, and D to Z, etc. Mono alphabetic cipher causes difficulty in cracking the message as there are random substitutions and a large number of permutations and combinations are available.

#### 3. Homophonic Substitution Cipher

A homophonic substitution cipher is similar to a monoalphabetic cipher; the only difference is in a monoalphabetic, we replace the alphabet with any other random alphabet except the original alphabet, wherein in a homophonic substitution cipher, the alphabet is replaced by a fixed alphabet or set of alphabets. The substitution alphabet is replaced with the fixed one. For example, replace A with x, E with B, S with A, etc., or replace A with E, x or L, B with T, A, Z, etc.

#### 4. Polygram Substitution Cipher

In Polygram Substitution cipher, rather than replacing each alphabet with another, the alphabet’s Block is replaced with another block of alphabets. Replace EDUCBA with XYQLAB. In this case, EDUCBA will replace with XYQLAB, but EDU can be replaced with another set of block. Let’s assume EDU will replace with LOD. In this type of cipher, plain text replacement is done block by block rather than character by character.

#### 5. Polyalphabetic Substitution Cipher

Polyalphabetic Cipher is also known as Vigenere Cipher, which Leon Battista Alberti invents. In Polyalphabetic Substitution, Cipher is a method of encrypting alphabetic texts. It uses multiple substitution alphabets for encryption. Vigener square or Vigenere table is useful to encrypt the text. The table contains 26 alphabets written in different rows; each alphabet is cyclically shifted to the left according to the previous alphabet, equivalent to the 26 possible Caesar Ciphers. The cipher uses a different alphabet from one of the rows at various points in the encryption process.

Let’s consider Original text is Educba, and the keyword is Apple. For the encryption process, E is paired with A, the first letter of the original text, and E, is paired with A, the first letter of the key. So use row E and column A of the Vigenère square, which is E. Similarly, for the second letter of the original text, the second letter of the key is useful, and the letter at row d and column p is s. The rest of the original text is enciphered in the same way. The final encryption of Educba is Esjnfa.

#### 6. Playfair Cipher

Playfair cipher is also called Playfair square. It is a cryptographic technique that is used o encrypt the data. The Playfair cipher process is as follows:

- Creation and population of the matrix.
- Encryption process.

Let’s discuss the above-mentioned steps in detail manner the creation and population of the matrix. It uses a 5 * 5 matrix to store the keyword or the key, which is used for the encryption and decryption process.

This step is working as follows.

- Enter the keyword in the matrix in a row-wise manner, i.e., from left to right and top to bottom.
- Skip the duplicate words in the keyword.
- Fill the remaining spaces with the rest of the alphabet (A – Z) that were not a part of the keyword.

**Note:** while doing so, combine I and J in the same cell of the table. i.e., If I or J is present in the keyword, discard both I and J while filling the remaining space encryption process.

The encryption process works as follows:

- Break the alphabet into groups (each group must contain two values). The encryption processes will be on these groups.
- If both alphabets in the group are the same, add x after the first alphabet.
- If both the alphabets in the group are present in the same row of the matrix, replace them with the alphabets to their immediate right, respectively. If the original group is on the right side of the row, then wrapping around the row’s left side happens.
- If both the alphabets in the group are present in the same column, replace them with the next immediate alphabets respectively. If the original group is on the bottom side of the row, then wrapping around to the row’s top side happens.
- If both the alphabets in the group are not in the same row or column, replace them with the alphabet in the same row immediately but at the other pair of corners of the rectangle, which the original group defines.

#### 7. Hill Cipher

Hill cipher works on multiple alphabets at the same time. Hill cipher works as follows:

- Assign the number to each alphabet in plain text. A = 0, B= 1….z = 25
- Organize the plain text message as a matrix of numbers based on the above step in number format. The resultant matrix is a plain text matrix.
- Multiply the plain text matrix with a randomly chosen key. Note that the key matrix must be the size of n*n, where n stands for the number of rows in a plain text matrix.
- Multiply both the matrix, i.e., step 2 and step 3.
- Calculate the mod 26 value of the above matrix, i.e., matrix results in step 4.
- Now translate the numbers to alphabets, i.e., 0 =A, 1 =B, etc.
- The result of step 6 becomes our ciphertext.

### Recommended Articles

This is a guide to Types of Cipher. Here we discuss the basic concept and various types of cipher, which include Caesar, Monoalphabetic, and Homophonic Substitution Cipher, respectively. You may also look at the following articles to learn more –

- Symmetric Algorithms
- What is SFTP?
- Advanced Encryption Standard
- Cryptosystems

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## What is a Cipher? Types of Ciphers in Cryptography

Ciphers are often grouped based on their operation and how their key is applied to encryption and decryption. Block ciphers combine symbols into a fixed-size message (the block), whereas stream ciphers use a continuous stream of symbols.

The same key is used for encryption and decryption when utilizing a symmetric critical method or cipher. Asymmetric vital algorithms or ciphers employ a different key for encryption and decryption.

Are you looking into ciphers? Then you have come to the correct location. This blog covers almost all types of ciphers in cryptography.

## What is Cipher?

- The cipher algorithm is commonly used in cryptology, a field dealing with the study of cryptographic algorithms. This technique is used to encrypt and decrypt data.
- The secret or symmetric key encryption will depend on the symmetrical cipher used.
- The same cipher and encryption key are used in the same manner by the symmetric method to encrypt and decrypt the data.
- Symmetric key encryption, often known as secret key encryption, is built on symmetric ciphers.
- It can be a goal to convert plain text to ciphertext or vice versa.
- Ciphers change data by converting letters or other plaintext into ciphertext. The ciphertext should be presented in the form of random data.
- By analyzing the original and plaintext data, the cipher creates a ciphertext that seems to be random data.
- No matter whether the goal is to convert plaintext into ciphertext or ciphertext into plaintext, the same encryption key is used to encrypt data in the same way, utilizing symmetric encryption techniques.
- The ciphertext refers to the data generated through any technique.
- Modern cipher techniques enable network traffic encryption using private communication in a number of networking protocols, including TLS, or transport layer security.
- Many communication systems, like digital televisions, mobile devices, and ATMs, employ ciphers to provide security and privacy.

## How Does a Cipher Work?

- Ciphers use an encryption method to change plaintext, a readable communication, into ciphertext, which appears to be a random string of letters.
- Ciphers are also called stream ciphers since they can encrypt or decrypt bits in a stream.
- They can also use block ciphers, which break up ciphertext into uniform units of a predefined number of bits.
- Modern cipher implementations change data as it is encrypted using the encryption method and a secret key.
- Ciphers more resist brute-force attacks when their keys are longer (measured in bits).
- Depending on the algorithm and use case, professionals recommend that current ciphers be designed with at least 128 bits or more, even if the key length is not necessarily connected with cipher strength.

- Because a key is such a vital component of an encryption process, the key is maintained as a secret rather than a procedure in real-world ciphering.
- Even if someone is familiar with the procedure, a robust encryption mechanism should make reading the ciphertext with the necessary key easier.
- As a result, a cipher requires the possession of a key or set of keys by both the sender and the recipient to work.
- The same key is employed in symmetric essential data encryption and decryption techniques.
- Asymmetric key algorithms encrypt and decrypt data using public and private keys.
- Asymmetric public key cryptography, commonly known as asymmetric encryption, uses large integers that have been paired but are not equal.

**Following is a snapshot of a key pair:**

- The public key is accessible to everyone.
- The secret key sometimes called the private key, is kept hidden.
- A message can be encrypted with any key and decoded using the opposite key that was used to encrypt it.
- The public key is used to encrypt messages that can only be read by the private key owner, even if the key pair only uses the private or secret key to encrypt or decrypt data.

## Why are Ciphers important?

By converting messages into a format that is unreadable or unintelligible to unauthorized parties, ciphers guarantee the confidentiality and integrity of communications.

Information and data are encrypted using ciphers so only those with the proper key or password can see it.

Additionally, ciphers are utilized for message verification, digital signatures, and authentication. Using ciphers can guard against data theft, eavesdropping, and hacking attempts and secure sensitive information.

Symmetric ciphers are the most used ones for protecting internet communication. Additionally, they are included in several protocols for data-sharing networks.

In particular, when combined with HTTP Secure (HTTPS), TLS and Secure Sockets Layer use ciphers to encrypt data at the application layer.

Virtual private networks that connect employees in remote or branch offices to corporate networks utilize protocols that encrypt data transmission using symmetric vital methodologies.

Symmetric ciphers are frequently employed in wireless Internet networks, e-commerce, banking websites, and mobile phone services to protect user data privacy,

Several protocols use asymmetric cryptography to authenticate and encrypt endpoints.

It also protects the transfer of symmetric keys used for session data encryption. **These standards comprise the following:**

- HTTP
- Secure Shell
- Open Pretty Good Privacy
- TLS
- Secure/Multipurpose Internet Mail Extensions

## Types of Ciphers in Cryptography

**There are several methods to categorize ciphers, including the following:**

Ciphers can be categorized using a variety of techniques, such as the ones listed below:

### Block Ciphers

Data is encrypted in equal-sized blocks using **Block ciphers**.

Block ciphers are symmetric vital algorithms that work with fixed-length data blocks to produce encrypted results. The data is encrypted and decrypted using a fixed-length key.

The input data is separated into equal-sized blocks, and the algorithm uses the same key for all the blocks to operate independently on each block. Advanced Encryption Standard (AES), Triple DES (3DES), and Data Encryption Standard (DES) are a few examples of block cipher.

### Stream Ciphers

Data streams often received and sent across a network can be encrypted using **Stream ciphers.**

On the other hand, the symmetric vital techniques used by stream ciphers encrypt and decode data one bit or byte at a time. They create a keystream, which is used to encrypt and decrypt the data using a key and an initialization vector (IV).

The encrypted output is created by combining the keystream with the plaintext using an XOR technique. Applications where data is sent in real-time, such as video and audio communication, frequently use stream ciphers. The stream ciphers RC4, and Salsa20 are a couple of examples.

### Caesar Cipher

Julius Caesar is believed to have used this cipher **to travel securely** with his men.

In this simple substitution cipher, each letter of the plaintext is relocated a predetermined number of places down the alphabet. Caesar is alleged to have worked three shifts.

Substitution ciphers are typically implemented by writing down the plaintext alphabet, followed by the ciphertext alphabet, shifted by the number decided upon by the participants. A three-letter shift puts the letter D over the plaintext letter A, E over B, etc. The number of characters shifted is a basic form of a key.

### Atbash

With this encryption, the plaintext alphabet is projected back onto itself as **a replacement cipher**.

The plaintext letters A through C are converted into the ciphertexts Z through Y, respectively. The names of Atbash are taken from the first and last letters of the Hebrew alphabet. Hundreds of years have passed since it hadn’t been utilized.

### Simple Substitution Cipher

This one has also been in use for a very long time. It creates **a 26-character key** by substituting a new ciphertext character for each plaintext letter.

In contrast to the Caesar cipher, the enciphering alphabet is mixed up instead of only being shifted a specific number of times.

### Playfair Cipher

Instead of using single letters as in a basic substitution cipher, **pairs of letters** are encrypted in this approach.

A key table is first created in the Playfair cipher. The plaintext is encrypted using the key table, a 55-grid of alphabets. One letter of the alphabet (often J) is left off the table because we only need 25 rather than 26, and each of the 25 must be distinct. J is changed to I if it is found in the plaintext.

### Vigenère

This polyalphabetic substitution cipher, which uses **several alternative alphabets**, suggests that it is based on substitution. Caesar ciphers based on a keyword’s letters are used as part of the Vigenère encryption in a sequence of interconnected patterns.

The Vigenère square or table is used to jumble up the source material.

### Enigma Cipher

The Germans used a sophisticated cipher system in World War II. After **scrubbing input plaintext**, it used several revolving wheels, connectors, and wires to encrypt the output. The key to this cipher was the original alignment of the wheels and plugboard structure.

### One Time Pad Cipher

One Time Pad Cipher is an **unbreakable cipher** that encrypts and decrypts communications using a random key called the one-time pad. The key is never reused and is as long as the message is encrypted. The key is a “one-time pad” since it can only be used once.

## Wrap up!

In conclusion, ciphers are a crucial type of encryption for securing private data. The security of the key is the core of every cipher, even though several ciphers have been developed over time, each with distinct advantages and disadvantages. We expect the development of increasingly more sophisticated encryption methods as technology advances.

## FAQ’s

### What are the different types of ciphers in cryptography?

- Block ciphers
- Stream Ciphers
- Substitution ciphers
- Transposition ciphers
- One Time Pad Cipher etc.

### What is the difference between Ciphers and Cryptography?

It is the process of turning ordinary text into a cipher that requires a key to decipher. Security of a message through encryption and decryption is defined as cryptography.

The use of cryptography is known as encryption. It is the skill of creating codes using encryption and decryption techniques.

**What are the four basic types of encryption systems?**

- Advanced Encryption Standard (AES)
- Blowfish.
- Rivest-Shamir-Adleman (RSA)
- Triple DES.

### Which is the More Secure Cipher?

**AES Encryption**

Governments, security agencies, and regular companies use the Advanced Encryption Standard (AES), one of the most secure encryption forms, for sensitive communications. “AES uses symmetric” key encryption.

### What is a Cipher in Cryptography?

Systems for encrypting and decrypting data are called ciphers, often known as encryption algorithms. A cipher uses a key to reveal the process by which it transforms the original message, known as plaintext, into ciphertext.

Published June 23, 2023

## Janki Mehta

Janki Mehta is a passionate Cyber-Security Enthusiast who keenly monitors the latest developments in the Web/Cyber Security industry. She puts her knowledge into practice and helps web users by arming them with the necessary security measures to stay safe in the digital world.

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