Token Seed Splitting for Multi-Factor Authentication Security
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Solution Overview
Problem
Existing multi-factor authentication systems that store the token seed on user devices are vulnerable to exposure due to risks like theft or loss, as they rely on native device protection methods that can be disabled and password-based encryption that lacks flexibility and biometric capabilities.
Innovation Solution
The token seed is split into three shares using a secret sharing technique, with a fixed share derived from the user's PIN, a remote share stored on a server, and a local share encrypted and stored on the device, allowing reconstruction using any two shares, enabling secure token code generation both online and offline, and facilitating biometric authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the complete token seed is stored on the user device using native device protection methods, then the token seed is protected to some extent, but the protection can be disabled by the user and does not support biometric authentication
Solution Approach 1:
The token seed is divided into multiple shares using secret sharing techniques. The first share is derived from the user's PIN through key derivation, the second share is stored on a remote server, and the third share is stored locally on the device. This segmentation allows the system to reconstruct the token seed without relying on a single protection method, enabling both strong security and biometric authentication support.
2Ease of operation
If the token seed is stored on the user device, then it is readily available for authentication, but the device theft or loss exposes the token seed to malicious parties
Solution Approach 1:
The token seed is split into multiple shares distributed across different locations (local device and remote server). Even if the device is stolen, the attacker only obtains one share which is insufficient to reconstruct the token seed. The user can recover authentication capability by providing biometric data to retrieve the remote share and reconstruct the token seed on a new device.
Solution Approach 2:
A remote server acts as an intermediary to store one share of the token seed. This intermediary enables the system to balance between having the token seed readily available locally and protecting it from device theft. The server can be accessed through secure biometric authentication to retrieve the necessary share for reconstruction.
3Reliability
If password-based encryption is used to protect the token seed, then the token seed is encrypted, but the method lacks flexibility and does not allow biometric integration
Solution Approach 1:
The system replaces traditional password-based mechanical encryption with a cryptographic approach using key derivation functions and secret sharing. Instead of relying on device-native protection mechanisms, the system uses cryptographic operations that can work with multiple authentication methods including biometrics. The key derivation function transforms the PIN into a cryptographic key, while biometric data serves as an alternative authentication credential to retrieve stored shares.
Data Source
AI summary
New techniques are disclosed for protecting a token seed in a multifactor authentication system. A personal identification number is used to derive a fixed share, and the token seed is split, using a secret sharing technique, into a set of three shares made up of the fixed share, a remote share, and a local share, such that the token seed can only be reconstructed using any two of the three shares. The remote share is stored on a remote authentication server, and an encrypted version of the local share is stored on the user device. The remote share may be encrypted by performing a key wrapping operation on the remote share using the local share, and then storing the encrypted version of the remote share on the remote authentication server. The token seed, fixed share, remote share and local share may then be deleted from the user device.