What is Cryptography ?

Cryptography: This topic covers the use of encryption and other cryptographic techniques to protect data and communications. This includes:

1. Symmetric key encryption: This is a type of encryption that uses a single secret key to encrypt and decrypt data. It is considered less secure than Asymmetric key encryption.
2. Asymmetric key encryption: This is a type of encryption that uses a pair of keys, one for encryption and one for decryption. This type of encryption is considered more secure than symmetric key encryption as the encryption key can be public while the decryption key can be private.
3. Hash functions: This is a type of algorithm that takes an input (or 'message') and returns a fixed size string of characters, which are the hash code. These codes are unique and any change in the input will result in a completely different hash code.
4. Digital signatures: This is a technique used to ensure the authenticity of digital messages or documents by attaching a unique digital signature to them.
5. Public Key Infrastructure (PKI): This is a system of digital certificates, certificate authorities, and other related technologies and protocols used to secure networks and communications using public key encryption.