The secure file transmission mechanism, depicted in the diagram below, has the following properties

• Authentication: Alice has a unique securely-held private key
• Non-repudiation: Alice has a unique securely-held private key
• Data Integrity: Program signs data using Alice’s private key
• Data Confidentiality: Program encrypts data using Alice’s private key

graph LR Program-->Server subgraph Alice priva["Alice's Private Key"]-->Program pubb["Server's Public Key"]-->Program file1["File"]-->Program end subgraph Server privb["Server's Private Key"]-->Server puba["Alice's Public Key"]-->Server Server-->file2["File"] end

Here’s how the mechanism works

1. Program calculates a secure hash of file data
2. Program encrypts file data using a randomly generated secret key
3. Program encrypts hash and secret key using Alice’s private key, and Server’s public key
4. Program transmits all encrypted data to Server
5. Server decrypts hash and secret key using its private key and Alice’s public key
6. Server decrypts file data using secret key
7. Server calculates hash of file data and compares it with hash sent by Program