What is Cryptography in Cyber Security? Types of Cryptography

What is cryptography in cyber security, and what are the different types of cryptography? We will talk about these things in this write-up. Moreover, the discussion will also be on numerous important concepts related to cryptography, such as:

• Substitution ciphers

• Data Encryption Standard (DES)

• Diffie-Hellman Key Exchange

• Advanced Encryption Standard (AES)

• Hybrid Cryptosystem

• Non-repudiation

• Elliptic Curve Cryptography (ECC)

• Cryptographic hashing

• Certificate Authority

• Pretty Good Privacy (PGC)

And much more related to cryptography.

It is one of the most important topics in cyber security, which we are covering here as part of our comprehensive Ethical Hacking Tutorial for Beginners. Let’s get started!

The process of scrambling data or converting it into a secret code so that only authorized users can understand it is called encryption. Technically, encryption converts the human-readable text (plaintext) to unclear text (ciphertext). 

For decryption, it requires a cryptographic key (a value agreed upon by the sender and receiver). The process of encryption and decryption is called cryptography. 

The formulas used for encoding and decoding the text are termed encryption algorithms or ciphers. 

The role of encryption is to secure the data in transit or in communication. For example, if someone is shopping online and making payments, encryption is used there to protect the data sent by the user to the site’s server.

It also secures several IT assets, enables confidentiality of messages and data, avoids modification during transmission, and secures sensitive data like banking details.

Now that you have a good idea of what is cryptography means, let’s know about the two types of it.

1. Symmetric Key Cryptography

Symmetric Key Cryptography involves only a single private key to encrypt and decrypt the information. Also called symmetric encryption, both parties use the same key where one uses it to encrypt, while the other party uses it to decrypt. 

Here, the data being transmitted is converted to an unreadable format and can’t be inspected without the secret key used for encryption.

It is the most preferred way of encryption because of its efficiency. Some examples of symmetric key cryptography or symmetric encryption are AES, DES, and 3DES. 

2. Asymmetric Key Cryptography

In Asymmetric Key Cryptography, different keys are used to encrypt and decrypt the data. A pair of Public Keys and Private Keys work together for the entire process. For encryption, a public key is used. Whereas, for decryption, a private key is used.

Below are some of the most important topics related to cryptography. You must know exactly what is cryptography in cyber security and have a good knowledge of the below-mentioned things.

1. What are Substitution Ciphers in Cryptography?

Substitution Ciphers is the method of replacing a set of characters with other characters on the basis of a key. For example, if the key is 1, then the letter will be replaced by B, B by C, C by D, and so on. 

Hence, it encrypts the text by substituting all the letters with a different character, based on the key entered. Let’s take a comprehensive example:

• Plain text: I am learning encryption

• Key: 4

• Result: M eq plevrmrk Irgvctxmsr

It becomes difficult for hackers to read and understand the text converted using the substitution ciphers method.

2. What is Diffie-Hellman's Key Exchange in Cryptography?

It was one of the earliest methods of sharing cryptographic keys publicly in a secure manner. Though created by Ralph Merkle, it was named after Whitfield Diffie and Martin Hellman. 

DH Key Exchange was used for a long time as a secure way of exchanging private keys and the related public key. In this method, the two parties needed to use a public key for encryption and decryption of the data or conversations. DH algorithm is based on symmetric cryptography.

3. What is Data Encryption Standard (DES)?

DES was created by IBM in the 1970s for the encryption of confidential data. Based on symmetric key cryptography, it was adopted by the US Government to protect sensitive and unclassified data. 

It was later modified to make it stronger against differential cryptanalysis. However, it was not highly efficient against brute-force attacks. DES was then succeeded by Advanced Encryption Standard (AES) to protect against brute-force attacks as well. 

4. What is the Advanced Encryption Standard (AES)?

AES is one of the most adopted symmetric encryption protocols that is considered around six times faster as compared to DES. It came as a replacement to DES because of its high efficiency and ability to prevent cyber threats.

Advanced Encryption Standard has symmetric key symmetric block cipher, offers full specification, and design details, and uses 128-bit data and 128/192/256-bit keys. Faster and more secure than triple-DES, AES is written in C and Java. 

AES is part of the ISO/IEC 18033-3 standard, as well as the US federal government standard. It is the only publicly accessible cipher that got approval from the US NSA (National Security Agency).

5. What is Hybrid Cryptosystem?

A hybrid cryptosystem brings together the convenience of public-key cryptography and the efficiency of symmetric key cryptography. 

The benefit of using a hybrid cryptosystem is that it enables the encryption of a message or data for multiple receivers. It has become a great fit for multi-user scenarios where the decryption can be limited to particular users. It is also a good option for the encryption of long messages.

6. What is Non-Repudiation?

It is a process used to guarantee the successful transmission of a message or date between two parties. A core pillar of information assurance, non-repudiation is mostly preferred for digital contracts, emails, and digital signatures. 

When non-repudiation is used, the other party can’t deny that they didn’t receive the message. It is a legal concept for the security of information, offering the origin and integrity of data. 

7. What is Elliptic Curve Cryptography (ECC)?

ECC is another popular method for data encryption that uses pairs of public and private keys to encrypt and decrypt the data. 

Elliptic Curve Cryptography is a more powerful cryptography technique than Rivest-Shamir-Adleman (RSA). While RSA provides one-way encryption for data, email messages, and software, the ECC uses key pairs with the mathematics of elliptic curves. 

Over the years, the adoption of ECC is growing because of its smaller key size, the capability of security maintenance, and high performance. The number of websites adopting ECC is on the rise as businesses look to secure the data of customers and optimize for websites.

8. What is Certificate Authority (CA)?

Certificate Authority or Certification Authority (CA) is a company or entity that issues digital certificates, such as an SSL certificate for websites. 

The role of a CA is to validate the identities of websites, companies, email addresses, etc. The digital certificates issued by a Certificate Authority provide encryption, authentication, and integrity. 

Both the owner of a digital certificate and the party relying on the owner trust the digital certificate. For example, if a website uses an SSL certificate, the URL shows HTTPS with a green padlock icon, which is a sign of trust for the visitors. Otherwise, it will show HTTP with a not secure warning. Hence, digital certificates establish trust.

9. What is Trusted Third Party (TTP)?

A Trusted Third Party (TTP) is a company or entity in a community that is trusted by all the entities in the community for a specific service. For example, a Certificate Authority is also a trusted third party that is trusted by the community of website owners. 

The role of a trusted party is to secure the data, messages, emails, and transactions between communities and their end users.

10. What is Self-Signed Certificates?

Self-signed certificates are those which are not issued by a Certificate Authority. These certificates are issued and signed with their own private keys. 

There are both pros and cons to a self-signed certificate. If used for internal networks and software development processes, it is considered more secure and beneficial. However, if it is not controlled and managed the right way, there can be security risks. Moreover, one can’t revoke a self-signed certificate, like the one issued by a CA. 

11. What is Cryptographic Hashing?

The cryptographic hashing technique is used for the conversion of data into unique strings of text. Regardless of the type and size of data, it can be hashed with this method. Hash functions in cryptography are considered very useful in almost every information security application. 

It is a mathematical function that works only one way, which means you can convert data into a unique string, but can’t put the string to get the input data. The converted values by cryptographic hashing are known as hash values or message digest. 

12. What is Pretty Good Privacy (PGP) in cryptography?

Pretty Good Privacy is a software package created to secure email communications. The process of PGP takes care of several aspects of email security, including authentication, compatibility, confidentiality, segmentation, and compression. 

PGP is considered a reliable service for both personal and official email messages. It works only for plain texts in an email, and not for multimedia files like images. 

13. What is Secure/Multipurpose Internet Mail Extension (S/MIME) in cryptography?

S/MIME is a protocol for the encryption of emails on the basis of asymmetric cryptography. While PGP is meant for plain text, it also allows multimedia files and verification of the digital signs of the sender. Verified digital signatures are a symbol of trust and help recipients avoid phishing attacks.

This is an expensive option compared to PGP because it offers encryption for both text and multimedia emails, and is an ideal fit for industrial purposes.