Modern encryption is the key to advanced computer and communication security. This stream of cryptography is completely based on the ideas of mathematics such as number theory and computational complexity theory as well as concepts of probability. In this chapter, you will learn about the different elements and characteristics of modern cryptography.

**Table of Contents**

### Types of Modern Cryptography

Different algorithms have come up with powerful encryption mechanisms incorporated in them. It gave rise to two new ways of encryption mechanism for data security. These are:

- Symmetric key encryption
- Asymmetric key encryption

**Key:** It can be a number, word, phrase, or any code that will be used for encrypting as well as decrypting any ciphertext information to plain text and vice versa.

Symmetric and asymmetric key cryptography is based on the number of keys and the way these keys work. Let us know about both of them in details:

### Symmetric Key Encryption

Symmetric key encryption technique uses a straight forward method of encryption. Hence, this is the simpler among these two practices. In the case of symmetric key encryption, the encryption is done through only one secret key, which is known as "Symmetric Key", and this key remains to both the parties. The same key is implemented for both encodings as well as decoding the information. So the key is used first by the sender prior to sending the message, and on the receiver side, that key is used to decipher the encoded message.

One of the good old examples of this encryption technique is Caesar's Cipher. Modern examples and algorithms that use the concept of symmetric key encryption are RC4, QUAD, AES, DES, Blowfish, 3DES, etc.

### Asymmetric Key Encryption

Asymmetric Encryption is another encryption method that uses two keys, which is a new and sophisticated encryption technique. This is because it integrates two cryptographic keys for implementing data security. These keys are termed as Public Key and Private Key. The "public key", as the name implies, is accessible to all who want to send an encrypted message. The other is the "private key" that is kept secure by the owner of that public key or the one who is encrypting.

Encryption of information is done through public key first, with the help of a particular algorithm. Then the private key, which the receiver possesses, will use to decrypt that encrypted information. The same algorithm will be used in both encodings as well as decoding. Examples of asymmetric key encryption algorithms are Diffie-Hellman and RSA algorithm.

#### Security Provided by These Cryptography Algorithms

- Confidentiality of information.
- Data Integrity.
- Authentication.
- Message authentication.
- Entity authentication.

- Non-repudiation.

#### Techniques Work in Combination With Modern Cryptography

- Encryption and its key
- Hash functions
- Message Authentication Codes (MAC)
- Digital Signatures

#### Advantages and Characteristic Differences Between Classical/Traditional Encryption and Modern Encryption

Here are the marked differences between the classical as well as the modern encryption techniques:

Traditional Encryption | Modern Encryption |
---|---|

For making ciphertext, manipulation is done in the characters of the plain text. | For making ciphertext, operations are performed on binary bit sequence. |

The whole of the ecosystem is required to communicate confidentially. | Here, only the parties who want to execute secure communication possess the secret key. |

These are weaker as compared to modern encryption. | The encryption algorithm formed by this encryption technique is stronger as compared to traditional encryption algorithms. |

It believes in the concept of security through obscurity. | Its security depends on the publicly known mathematical algorithm. |