Blinded Token Authentication and IMSI Swapping for Mobile Privacy
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Solution Overview
Problem
Existing mobile device authentication methods expose user privacy risks due to the static and unencrypted nature of International Mobile Subscriber Identity (IMSI) values, and require users to trust service providers with their identifying information.
Innovation Solution
A method utilizing blinded tokens in a blind signature scheme for mobile device authentication, which allows devices to prove possession of a validated receipt identifier without revealing their identity, combined with an IMSI value swapping mechanism that changes IMSI values in response to triggers to enhance privacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional authentication methods using username and password are used, then user identity can be verified, but user privacy is compromised as identifying information must be exposed to the service provider
Solution Approach 1:
The patent introduces blinded tokens as an intermediary mechanism between the user and service provider. The token contains proof of authentication credentials without exposing the actual credentials. The service provider can verify the token's validity without learning the underlying username or password, thus maintaining authentication reliability while protecting user privacy through cryptographic blinding techniques.
Solution Approach 2:
The patent creates a cryptographic copy or representation of authentication credentials in the form of blinded tokens. Instead of transmitting actual credentials, the system transmits a verified copy that proves authenticity without revealing the original sensitive information. This allows the service provider to verify user identity without accessing or storing actual username-password pairs.
2Ease of operation
If IMSI values are transmitted unencrypted during network attach, then mobile device can connect to network, but device is exposed to unauthorized tracking
Solution Approach 1:
The patent applies preliminary cryptographic blinding to the IMSI value before transmission. The mobile device generates a blinded version of the IMSI through cryptographic operations before sending it to the network. This preliminary action ensures that even though the IMSI is transmitted during network attach, it remains encrypted and unusable for tracking purposes, while still allowing network connectivity through the blinded identifier.
Solution Approach 2:
The patent transforms the IMSI parameter from its original unencrypted form to a blinded cryptographic form. By changing the state of the IMSI through cryptographic blinding operations, the system maintains the functional property of network identification while removing the harmful property of traceability. The blinded IMSI can still be used for network attachment but cannot be used to track the user's movement or behavior.
3Device complexity
If static IMSI values are used for authentication, then device identification is simplified, but user privacy is compromised through consistent identification
Solution Approach 1:
The patent transforms the static IMSI value into a dynamic identifier through cryptographic blinding. Each time the mobile device needs to authenticate or attach to the network, a new blinded version of the IMSI is generated. This dynamic approach maintains the simplicity of device identification (the device still has one underlying IMSI) while preventing privacy exposure because the identifier changes with each use, making tracking infeasible.
Data Source
AI summary
A mobile device performs authentication with blinded tokens and swaps its international mobile subscriber identity (IMSI) value. For authentication with blinded tokens, the mobile device generates a blinded token and provides it to a server to encrypt. To redeem the token, the mobile device unblinds the encrypted blinded token and provides it to the server along with a public key. To complete authentication, the mobile device receives, from the server, a nonce encrypted with the public key and decrypts the nonce with a private key. For swapping its IMSI value, the mobile device retrieves two eSIM profiles with corresponding IMSI values and configures the first of the two profiles as active. In response to a trigger, the mobile device changes the active profile from the first to the second, swaps the first IMSI value with a new IMSI value, and changes the active profile back to the first profile.