An application is instrumented with a document protection service provider interface (SPI). The interface is used to call an external function, e.g., an encryption utility, to facilitate secure document exchange between a sending entity and a receiving entity. When the application invokes the SPI, the user is provided with a display panel. The end user provides a password for encryption key generation, together with an indication of desired encryption strength. The service provider uses the password to generate an encryption key. In one embodiment, the service provider provides the key to the service provider interface, which then uses the key to encrypt the document and to complete the file transfer operation. In the alternative, the service provider itself performs encryption. The SPI generates and sends a message to the receiving entity that includes the key or a link to enable the receiving entity to retrieve the key.