An encryption system, method, and computer software program product provides encrypted transmission of data between a server and a web browser application on a client computing device. The system includes an Internet browser; a JavaScript data encryption library; a public key encryption algorithm; a server; and a public private key pair of the user. The JavaScript library loads in user's browser and configured with symmetric and asymmetric encryption libraries and codes. Server sends an encrypted key data to the browser/JavaScript application. The user may then provide their private key and the JavaScript library decrypts the encrypted key data and obtains a symmetric key used to encrypt the data the server transmits to the browser during a session. With the server transmitting data in encrypted form, the browser is configured to decrypt the received data using the JavaScript data encryption library and the private key of the user.