Signed Merkle Tree End-to-End File Sharing Schema
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Solution Overview
Problem
Cloud providers face challenges in ensuring the trust and protection of customer data during file sharing, as existing end-to-end encryption schemas primarily focus on one-to-one communications and do not adequately address group file sharing or provide comprehensive security features like forward secrecy and privacy.
Innovation Solution
The implementation of an end-to-end encryption schema using a modified signed Merkle tree with randomly originated keys, which supports both one-to-one and one-to-many scenarios, provides authentication, forward secrecy, and ensures confidentiality and integrity of data, while also protecting privacy and anonymity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing end-to-end encryption schemas are used, then one-to-one communication security is improved, but group file sharing capability and comprehensive security features are insufficient
Solution Approach 1:
The encryption schema is designed to support both one-to-one and one-to-many communication scenarios through a unified protocol. The system uses a Merkle tree structure where the root hash serves as the group secret, enabling multiple receivers to share files securely while maintaining the same security guarantees as one-to-one communication. This multi-functional design resolves the contradiction by making the system adaptable to different group sizes and communication patterns without requiring separate protocols.
Solution Approach 2:
The group key management is segmented into individual receiver-specific decryption keys derived from the Merkle tree structure. Each receiver has a unique leaf node in the Merkle tree, and their decryption capability is tied to their specific path to the root. This segmentation allows the system to provide individualized security controls for each receiver while maintaining overall group security, enabling both one-to-one and group file sharing with appropriate security features for each scenario.
2Quantity of substance
If cloud providers implement traditional encryption, then data storage capability is improved, but trust and confidentiality protection deteriorate
Solution Approach 1:
The cloud provider acts as an intermediary that stores encrypted files and Merkle tree structures without having access to decryption capabilities. The system introduces a trust model where the cloud provider's role is limited to storage and transmission, while cryptographic operations occur client-side. This intermediary approach allows the cloud to provide storage capability while maintaining confidentiality, as the provider cannot access the actual data without the receiver's private keys.
Solution Approach 2:
Encryption and key derivation operations are performed preliminarily on the client side before data is transmitted to the cloud. The sender encrypts files using the group secret derived from the Merkle tree root, and the cloud provider only receives already-encrypted data. This preliminary cryptographic processing ensures that the cloud provider never handles plaintext, maintaining trust and confidentiality while enabling scalable cloud storage capability.
3Reliability
If Signal protocol is used, then content protection is improved, but privacy protection deteriorates
Solution Approach 1:
The system uses asymmetric cryptographic properties where the group secret (Merkle tree root) can be freely shared and verified, but individual decryption capabilities remain asymmetric and private. Each receiver's ability to decrypt is tied to their unique private key and Merkle path, creating an asymmetric trust model. This allows content protection through the shared group secret while maintaining privacy through asymmetric individual credentials, resolving the contradiction between content security and privacy preservation.
Data Source
AI summary
A process for transmitting a file from a sender device to a receiver device includes generating a random symmetric session key for the sender device, and randomly selecting a private ephemeral key for the sender device. The private ephemeral key is associated with a corresponding first public key. A public ephemeral key is randomly selected for the receiving device. The public ephemeral key is associated with a corresponding first private key. A random value is generated, an encrypted session key is calculated, and the file is encrypted using symmetric encryption. The sender device includes a first public X509 certificate comprising a second public key and a corresponding second private key that is signed by a service provider, and the receiver device includes a second public X509 certificate comprising a third public key and a corresponding third private key.