Public key cryptography allows for secure communication between two parties who have never met before because each party can generate their own public and private keys, and the public keys can be shared publicly without compromising the security of the private keys.

RSA and Diffie-Hellman are the two main types of public key cryptography algorithms. RSA is used for encryption and decryption, while Diffie-Hellman is used for key exchange.

RSA uses a public key and a private key to encrypt and decrypt messages. The public key is used to encrypt messages, and the private key is used to decrypt messages.

Diffie-Hellman uses a shared secret key to encrypt and decrypt messages. The shared secret key is generated by two parties using a public key exchange protocol.

A digital signature is a mathematical algorithm used to verify the authenticity of a message. It allows the recipient of a message to verify that the message was sent by the claimed sender and that the message has not been tampered with.

A certificate authority is a trusted third party that issues digital certificates. Digital certificates are used to verify the identity of a website or an individual.

The purpose of a public key infrastructure (PKI) is to provide a secure way to exchange public keys. This allows parties to communicate securely without having to share a secret key.

RSA is the most common type of public key cryptography algorithm used today. It is used in a wide variety of applications, including secure communication, digital signatures, and electronic commerce.

2048 bits is the key size for RSA typically used today. This provides a good balance between security and performance.

The Diffie-Hellman key exchange protocol is used to securely exchange a secret key between two parties over an insecure channel. This allows the parties to communicate securely without having to share a secret key in advance.

Elliptic Curve Cryptography (ECC) is a public key cryptography algorithm that uses elliptic curves. It is a more efficient alternative to RSA and is often used in applications where performance is critical.

The Digital Signature Algorithm (DSA) is a public key cryptography algorithm that uses digital signatures. It is a widely used algorithm for digital signatures and is often used in applications where security is critical.

The purpose of a certificate revocation list (CRL) is to list the certificates that have been revoked. This allows parties to verify that a certificate is still valid before relying on it.

The purpose of a certificate transparency log is to publicly record all issued certificates. This allows parties to verify that a certificate was actually issued by a certificate authority.