Public Key Infrastructure (PKI) - 1.4

Overview of Public Key Infrastructure (PKI)

Public Key Infrastructure (PKI) is a system that supports the creation, distribution, management, storage, and revocation of public and private cryptographic keys and digital certificates, providing the foundation for secure communications, digital signatures, and data encryption.

PKI enables secure exchange of information over untrusted networks by allowing users to authenticate identities and establish encrypted communication channels. It relies on Certificate Authorities (CAs) to issue and verify digital certificates, ensuring that public keys belong to verified entities.

Symmetric Encryption

Symmetric encryption uses a single, shared key for both encryption and decryption of data. While this method is highly efficient and fast, it presents significant security risks if the key is compromised, as anyone who has access to the key can decrypt the data.

Symmetric encryption is well-suited for encrypting large volumes of data because of its speed. However, securely distributing the symmetric key to the intended recipient presents a challenge, often requiring additional secure channels for key exchange.

Asymmetric Encryption

Asymmetric encryption, also known as public key cryptography, uses a pair of cryptographic keys: a public key and a private key. The private key is kept secret, while the public key is shared openly. Data encrypted with the public key can only be decrypted with the corresponding private key, ensuring secure data exchange.

This encryption method relies on mathematical algorithms involving properties of large prime numbers or elliptic curves, making it computationally infeasible to derive the private key from the public key.

Diffie-Hellman is an example of a key exchange protocol that enables two parties to jointly establish a shared secret over an insecure channel without directly transmitting the secret itself. Other commonly used asymmetric algorithms include RSA, which relies on the factorization of large prime numbers, and Elliptic Curve Cryptography (ECC), which offers similar security with smaller key sizes.

Key Escrow

Key escrow is a mechanism in which cryptographic keys are stored securely with a trusted third party or within an organization's secure infrastructure. This arrangement is used to ensure that encrypted data can still be accessed if a key is lost, or if an individual with access becomes unavailable.

In corporate environments, key escrow ensures that an organization retains control over critical information, even if the keys are held by an employee who leaves the company. Key escrow is particularly useful for data recovery and compliance with regulations that require organizations to have a method to decrypt critical data.

It is crucial to manage escrowed keys carefully to maintain security, as any compromise of the escrowed keys could result in unauthorized access to the encrypted data.