Custodian-Based Account Recovery for Encrypted Data Access
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Solution Overview
Problem
Existing account and data recovery techniques are vulnerable to cyber-theft and require complex credentials, degrading user experience, and encrypted data is inaccessible without the decryption key, which the cloud network service cannot provide.
Innovation Solution
Establish a custodial relationship between a user device and one or more custodian devices, using cryptographic material generated by the server and user device, with parts stored at each, and maintain anonymity through an anonymous identifier, ensuring integrity checks and secure communication to recover access to user accounts and encrypted data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If alternative stored information (e.g., answers to security questions) is used for account recovery, then access recovery is enabled, but the system becomes vulnerable to cyber-theft or misuse by untrusted third parties
Solution Approach 1:
The cryptographic material is divided into multiple parts and stored in different locations (custodian device and server). This segmentation ensures that no single point of failure or compromise can provide full access, thereby maintaining security while enabling recovery.
Solution Approach 2:
A custodian device is introduced as an intermediary between the user and the recovery system. This custodian holds a portion of the cryptographic material and provides a secure, trusted mechanism for account recovery without exposing the complete recovery credentials to potential threats.
2Reliability
If two-factor authentication is implemented, then security is improved, but the complexity of credentials and authentication process increases
Solution Approach 1:
The custodial relationship and cryptographic material distribution are established in advance during normal operation. This preliminary setup ensures that when recovery is needed, the process is simplified because the infrastructure is already in place, reducing the complexity during the actual recovery event.
3Reliability
If encrypted data is stored with end-to-end encryption, then data privacy is ensured, but the data becomes inaccessible without the decryption key
Solution Approach 1:
The decryption key (cryptographic material) is segmented into multiple parts stored in different secure locations (custodian device and server). This allows the complete decryption key to be reconstructed only when needed through the coordinated action of multiple trusted components, maintaining encryption security while enabling authorized access.
Solution Approach 2:
The system changes the state of the cryptographic material from a single static key to a distributed set of key parts that can be dynamically reconstructed. This parameter change enables the system to maintain strong encryption at rest while providing a controlled mechanism for key reconstruction when authorized.
Data Source
AI summary
This Application sets forth techniques for establishing a custodial relationship between a user device and a custodian device for recovering access to a user account and/or to encrypted user data with assistance provided by the custodian device to effect access recovery. A server of a cloud network service provides an anonymous identifier to associate with the custodian device and an account recovery key to store at the custodian device. Identity of an account of the cloud network service associated with the custodian device can be hidden from the server. The user device generates a data recovery key and provides a first portion of the data recovery key to the custodian device and a second portion of the data recovery key to the server. Integrity of the stored account recovery key and portions of the data recovery key are checked regularly by the custodian device and the user device.