Cryptography and encryption are very useful for data security. In today”s world, it is very important in protecting cyber data. The Internet allows computers to communicate with each other anywhere. But with that, a lot of intruders come in and try to make us care about what we do. People or companies whose job it is to keep data secure. Encryption is the primary way we do that. In this chapter we will discuss the various ways in which we use cryptography today for security purposes.

Modern cryptography uses complex mathematical techniques to encode information so that only the intended recipient can understand it. There are two main types of cryptography: symmetric and asymmetric cryptography.

As the technology is evolving around, so does cryptography and researchers are constantly developing new ways to get ahead of potential threats.

Classic Cryptography vs. Modern Cryptography

Classic and modern cryptography are both methods used to keep information secure but they are different in many ways let us discuss these one by one −

Technology

Classic cryptography is based on manual methods and mechanical devices like pen and paper, mechanical cipher machines (like Enigma), or simple electronic circuits.

While Modern cryptography uses advanced computing technologies like digital computers, specialized cryptographic hardware, and software algorithms.

Security Strength

Classic cryptography mostly relies on simple substitution or transposition techniques. This can be very easy for modern computers to crack mainly with the help of brute force attacks.

Modern cryptography uses more complex algorithms. This makes it more secure against attacks. It uses mathematical principles like prime number theory, discrete logarithms, and elliptic curves to create best encryption schemes.

Time Period

Classic cryptography used before the 20th century. And techniques like Caesar ciphers and the Enigma machine used in that time.

Modern cryptography is developed in the 20th and 21st centuries which uses advanced mathematical algorithms and computer technology.

Key Management

In the Classic cryptography the key management was very challenging because keys need to be shared securely between two parties without interception. This feature can make classic cryptographic systems vulnerable to attacks.

Modern cryptography uses asymmetric encryption in which each user has a pair of keys. A public key for encryption and A private key for decryption. This feature removes the need for key distribution and gives stronger security.

Applications

Classic cryptography was mainly used for military and diplomatic applications, as well as to get important information in ancient times and history.

Modern cryptography is everywhere in today”s digital world, being used for online transactions, financial transactions, data storage, and authentication methods such as protecting digital signatures and biometrics.

Overall, while classical cryptography laid the foundation for modern cryptographic principles, modern cryptography offers much stronger security and broader applications through advances in mathematics, computer technology, and cryptographic analysis.

Context of Cryptography

Cryptology, the study of cryptosystems, can be subdivided into two branches −

• Cryptography

• Cryptanalysis

What is Cryptography?

Cryptography is the science of making a cryptosystem with the ability to provide data security. Cryptography deals with the actual security of digital data. It describes the design of devices based on accounting systems that provide basic information security services. You can think of cryptography as a giant tool set with methods for security operations.

What is Cryptanalysis?

Cryptanalysis is the art and science of breaking cipher text. It is also the branch of cryptography. The cryptographic system generates cipher text that is transmitted or stored. It involves studying the cryptographic devices with a view to breaking them. Cryptanalysis is also used to test the security properties of new cryptographic techniques as they are developed.

Note − Cryptography deals with the design of cryptosystems and the cryptanalysis studies the breaking of cryptosystems.

Cryptography Primitives

Cryptography primitives are nothing more than tools and techniques in cryptography that can be selectively used to provide desired security services −

• Encryption

• Hash functions

• Message Authentication codes (MAC)

• Digital Signatures

The below table shows the primitives that can be achieved a particular security service on their own.

Note − To obtain a set of necessary security services from a cryptosystem, cryptographic primitives are commonly connected and have complex relationships with one another.