Why is a hybrid cryptosystem preferred over symmetric and public key encryption systems?

A hybrid cryptosystem combines features from both symmetric-key and public-key encryption systems. This approach overcomes their individual limitations.

Symmetric-key algorithms, such as AES, encrypt data quickly. However, distributing the shared secret key securely poses a challenge.

Public-key algorithms, like RSA, solve the key distribution problem. A public key can be openly shared. But, these algorithms are computationally intensive and slow for encrypting large amounts of data.

A hybrid cryptosystem uses public-key encryption to securely exchange a symmetric session key. Once this session key is established, the system uses the faster symmetric-key algorithm to encrypt the actual data. This method ensures secure key distribution while maintaining high performance for data encryption. It is a practical choice for most applications, including SSL/TLS.