Security Module Authentication Key Generation Protocol
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Solution Overview
Problem
Existing methods for changing network operators in mobile devices with security modules, such as SIM cards, require manual intervention and storage of root keys for all potential operators, posing security risks and logistical challenges, especially when devices are difficult to access.
Innovation Solution
A method for generating an authentication key in a security module that involves sending a transfer request to a second network entity, receiving and verifying secrets, and generating a second root key to access the new network without prior installation of the second entity's root key, ensuring secure transfer of control without manual intervention or storage of all root keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the root key of the second network entity is pre-installed on the security module before commissioning, then the authentication key can be generated for the second network, but the security module must be preconfigured for all potential operators which increases device complexity and storage requirements
Solution Approach 1:
The security module is preconfigured with only the root key of the first network entity before commissioning. The root key of the second network entity is generated on-demand through a key generation protocol initiated after the security module is already deployed and authenticated with the first network, eliminating the need for advance preconfiguration of all potential operators.
Solution Approach 2:
A key generation protocol acts as an intermediary mechanism between the security module and the network entities. This protocol enables secure generation and transmission of authentication keys without requiring pre-installation of all possible root keys, using the first network entity as a trusted intermediary to facilitate key generation for the second network entity.
2Reliability
If manual intervention is required to change security modules or authentication keys, then security can be maintained, but the ease of operation deteriorates especially when devices are difficult to access
Solution Approach 1:
The security module autonomously generates its own authentication key for the second network entity using the key generation protocol, without requiring manual intervention or physical access to the device. The process is initiated remotely through network communication, allowing the security module to service itself by generating and installing new authentication keys independently.
Solution Approach 2:
The manual mechanical process of physically replacing security modules or accessing devices is replaced by an electronic/key-based system. The key generation protocol substitutes the need for physical intervention with a cryptographic process that can be executed remotely through network communication, maintaining security while dramatically improving ease of operation.
3Ease of operation
If the second root key is transmitted over the network, then the authentication key can be generated, but security is compromised due to potential interception
Solution Approach 1:
The critical root key material is extracted from network transmission. Instead of transmitting the second root key over the network, the protocol generates authentication keys through a mathematical protocol where only non-sensitive intermediate values are exchanged. The actual root key remains localized and never leaves the security module or the generating network entity, eliminating the security risk of network interception.
Solution Approach 2:
The protocol transforms the transmission of sensitive key material into transmission of transformed parameters. Rather than sending the root key itself, the system exchanges mathematical parameters (such as random challenges and intermediate computation results) that can be used to derive authentication keys without revealing the root key, changing the nature of what is transmitted from sensitive to non-sensitive data.
Data Source
AI summary
The invention relates to a method for generating an authentication key in a security module which stores a first root key (K_root_A) shared with a first network entity, the method including the following steps:sending a transfer request to a second network entity,receiving a first secret (S_b1) from the second network entity,generating a secret generation key (Kb1) from the first root key and from the first secret,receiving from the second network entity a second secret (S_b2) and an authentication message of the second secret calculated by means of the secret generation key transmitted to the second network entity by the first network entity,verifying the authentication message by means of the secret generation key,generating a second root key (K_root_B) if the verification is positive, said second root key being generated from the second secret (S_b2) and from the secret generation key (Kb1), and used to generate an authentication key to access a network of the second network entity.