When a browser establishes an HTTPS connection, the encryption process is managed by the browser itself, utilizing the operating system's cryptographic libraries. These libraries, such as OpenSSL on Unix-based systems or the Windows CryptoAPI on Windows, provide the necessary functions for implementing the Transport Layer Security (TLS) protocol, which underpins HTTPS. The browser initiates the TLS handshake, negotiates encryption parameters, and handles the encryption and decryption of data transmitted between the client and the server. While the operating system's cryptographic libraries facilitate the encryption process, the browser is responsible for managing the overall HTTPS connection and ensuring secure communication.
It's important to note that the security of the HTTPS connection depends on the strength of the TLS implementation, which includes the choice of encryption algorithms and the proper validation of the server's SSL/TLS certificate. A compromised or invalid certificate can undermine the security of the connection, regardless of the encryption strength.
In summary, the browser handles the encryption of HTTPS connections, leveraging the operating system's cryptographic libraries to ensure secure communication between the client and the server.