Encrypted Media Data Sharing with Dynamic Key Revocation
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Solution Overview
Problem
Users lose control over their media data once it is shared on public platforms, as recipients can store and distribute copies, and the data may remain on servers even after deletion.
Innovation Solution
Media data is encrypted with a session key, which is encrypted using the recipient's public key, and managed by a key manager, allowing controlled access and decryption only when the owner shares the data, with client-side logic preventing copying and storage on the recipient's device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If media data is published on a public server for access by multiple users, then information exchange and collaboration are encouraged, but the owner loses control over the media data and recipients can keep copies for further distribution
Solution Approach 1:
The media data is encrypted with a session key before being uploaded to the public server. This preliminary encryption action ensures that even though the data is accessible to multiple users on the public server, only authorized recipients with the corresponding decryption key can access the actual content, thus maintaining owner control while allowing broad accessibility
Solution Approach 2:
A key management system acts as an intermediary between the data owner and recipients. The key manager controls the distribution of decryption keys to authorized recipients, enabling the owner to maintain control over who can access the media data without restricting the data's presence on the public server. This intermediary mechanism resolves the contradiction by decoupling data accessibility from access authorization
2Loss of substance
If the owner deletes media data from the website, then storage space is freed, but the website may keep copies or not actually delete the photos from storage devices
Solution Approach 1:
The decryption key is extracted and controlled separately from the encrypted media data. When the owner wants to delete data, they can revoke the decryption key through the key management system, effectively removing access to the data without needing to physically delete it from storage devices. This separates the data storage function from the access control function, ensuring reliable data deletion through key revocation
Solution Approach 2:
The system预先 establishes key management controls that enable future deletion. By setting up the key management infrastructure in advance, the owner can efficiently revoke access and ensure data deletion without the complexity of tracking and deleting copies across multiple storage devices, as the decryption capability itself is what enables access
3Ease of operation
If the recipient receives encrypted media data and decryption key, then the recipient can decrypt and view the media data, but the recipient can also copy and store the media data on their device
Solution Approach 1:
The system implements dynamic key management where decryption keys can be granted or revoked in real-time based on sharing status. This dynamic approach allows the recipient to easily view media data when authorized, while the owner can dynamically revoke access to prevent further copying or storage by simply removing the decryption key through the key manager, without needing to implement complex technical restrictions on the recipient's device
Data Source
AI summary
An owner of media data encrypts the media data using a session key. The session key is encrypted using a public key of a designated recipient of the media data. A key manager provides the encrypted session key to the recipient while the owner is sharing the media data with the recipient. The encrypted media data is published and accessed by the recipient over a public computer network. The encrypted session key and the encrypted media data are received in the recipient's computer, where the encrypted session key is decrypted into the session key using the recipient's private key and the encrypted media data is decrypted into the media data using the session key. When the owner is no longer sharing the media data with the recipient, the recipient is prevented from further receiving the encrypted session key from the key manager.