Digital Escrow Server Using Distributed Polynomial Secret Recovery
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Solution Overview
Problem
Existing digital escrow systems face challenges in maintaining confidentiality and security, particularly when multiple administrators are involved, as the dissemination of decryption keys increases the risk of data breaches and identity theft, and the loss of a single administrator can render encrypted data inaccessible.
Innovation Solution
An administration machine and infrastructure that utilize a polynomial function specific to each administration machine, allowing for cooperative recovery of encrypted data without reconstructing a single decryption key, ensuring security through distributed cryptographic operations and superencryption, where each machine can recover the escrow with a subset of machines, eliminating the need for a master key and maintaining confidentiality even if the server is corrupted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the decryption key is kept by a single administrator, then the confidentiality of the escrowed data is maintained, but the availability of the data is compromised if the administrator is no longer able to indicate the value of the decryption key
Solution Approach 1:
The decryption key is segmented into multiple parts distributed among multiple administrators. Each administrator holds a portion of the key, and a predetermined number of administrators must collaborate to reconstruct the full key for data recovery. This segmentation maintains confidentiality (no single administrator has the complete key) while ensuring availability (data can be recovered if a sufficient number of administrators are available).
2Ease of operation
If multiple administrators have knowledge of the decryption key value, then the availability of the escrow server is improved, but the confidentiality of the data is prejudiced as each administrator can decrypt the escrow
Solution Approach 1:
The decryption key is divided into multiple segments distributed to different administrators. Each administrator possesses only a portion of the key, which is insufficient for decryption on its own. This ensures that even if multiple administrators are compromised, the full key remains secure unless a sufficient number of administrators collude, thus maintaining confidentiality while enabling availability through distributed access.
Solution Approach 2:
Each administrator is assigned a specific local portion of the decryption key with defined access rights. The key material is distributed non-uniformly across administrators, with each receiving a unique segment that has no meaningful value without the other segments. This local quality assignment ensures that individual administrators cannot decrypt data alone, preserving confidentiality while allowing collaborative access for availability.
3Ease of operation
If a recovery key is provided for encrypted data, then the availability of data is improved, but the security is compromised due to the wider dissemination of key values allowing decryption
Solution Approach 1:
The recovery mechanism uses segmented key portions distributed among administrators rather than a single widely-disseminated recovery key. Each administrator holds a secure segment that cannot be used alone for decryption. This segmentation prevents the security compromise associated with widespread recovery key distribution while maintaining availability through the collaborative recovery process requiring multiple segments.
Data Source
AI summary
An administration machine for a digital escrow server stores integer values each corresponding to a machine of a group of administration machines. An initialization function calls a polynomial function, unique to the administration machine, of a degree less than or equal to the number of administration machines, with each integer value, in order to obtain first secret values. The function constructs a message including, for each administration machine, the first secret value corresponding to the integer value of said machine. In response to a message having, for each administration machine, a second secret value obtained on calling the polynomial function of said machine on the integer value of the administration machine, the function constructs a resulting secret value from the first and second secret values. An overlay function processes a digital escrow using the resulting secret value unique to the administration machine and resulting secret values unique to similar administration machines.