A Mutable Log

A blog by Devendra Tewari

---

Project maintained by tewarid Hosted on GitHub Pages — Theme by mattgraham

Secure file transmission using asymmetric cryptography

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

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