Publicly Verifiable Key Backup Using Threshold Secret Shares
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Solution Overview
Problem
Existing methods for verifying private key backups are inefficient and compromise security by requiring revelation of the private key, leading to increased computing and processing overheads.
Innovation Solution
A publicly verifiable encryption scheme using threshold secret sharing and verifiable threshold secret sharing to verify encrypted parts of a private key without revealing the key, reducing computing consumption by iteratively challenging a subset of decrypted parts to match a polynomial function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional private key backup verification methods are used, then verification can be performed, but the private key must be revealed which compromises security and increases computing overhead
Solution Approach 1:
The private key is segmented into multiple shares using secret sharing schemes (e.g., Shamir's Secret Sharing). Each share is encrypted separately, and no single share reveals the private key. Verification is performed by collecting a threshold number of shares and verifying their combined validity without reconstructing the full private key, thus maintaining security while enabling verification.
Solution Approach 2:
A verification mechanism using polynomial commitment schemes and zero-knowledge proofs is introduced as an intermediary. This intermediary allows verification of backup integrity by proving that encrypted shares correspond to valid polynomial evaluations without revealing the polynomial coefficients (private key). The verifier can confirm backup correctness through cryptographic proofs while the private key remains concealed.
2Productivity
If iterative challenging of subset of decrypted parts is implemented, then computing consumption is reduced, but verification complexity increases
Solution Approach 1:
Instead of verifying all encrypted shares completely, the system performs partial verification by iteratively challenging a subset of decrypted parts. The verifier requests proofs for only some shares at each iteration, and if a threshold number of shares are verified, the entire backup is considered valid. This partial action approach reduces computing consumption while maintaining verification reliability.
Solution Approach 2:
The verification process uses periodic iterative challenging where the verifier periodically selects random subsets of shares to verify across multiple rounds. This periodic sampling approach ensures that over time, sufficient shares are verified to guarantee backup integrity while distributing the computational load efficiently, reducing peak computing consumption compared to exhaustive verification.
Data Source
AI summary
Methods, systems, and devices for data management are described. A server may receive a plurality of parts of a secret from a computing device, where the plurality of parts may be individually encrypted and individually associated with respective public parts. The server may transmit a random challenge to the computing device. The computing device may transmit, to the server, a subset of parts in a decrypted state. The server may determine, using the subset of decrypted parts and a corresponding subset of respective public parts, that the subset of decrypted parts corresponds to a polynomial function with a degree corresponding to a quantity of parts in the subset of decrypted parts. The server may verify that the individually encrypted plurality of parts corresponds to a secret based on determining that the subset of decrypted parts corresponds to the polynomial function.