Key derivation for a module using an embedded universal integrated circuit card
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Publication Number
US-10187206-B2
Publication Date
2019-01-22
Expiration Date
Abstract
A module with an embedded universal integrated circuit card (eUICC) can include a received eUICC profile and a set of cryptographic algorithms. The received eUICC profile can include an initial shared secret key for authentication with a wireless network. The module can receive a key K network token and send a key K module token to the wireless network. The module can use the key K network token, a derived module private key, and a key derivation function to derive a secret shared network key K that supports communication with the wireless network. The wireless network can use the received key K module token, a network private key, and the key derivation function in order to derive the same secret shared network key K derived by the module. The module and the wireless network can subsequently use the mutually derived key K to communicate using traditional wireless network standards.
Core Innovation
The disclosed method securely distributes a profile containing wireless network access credentials from a subscription manager system to a module. The subscription manager system records cryptographic parameters, verifies a module certificate and challenge, and generates a network key pair. Using Elliptic Curve Diffie-Hellman, the system and module mutually derive a shared key based on their respective keys. The system encrypts the profile using an Advanced Encryption Standard symmetric cipher with a 128-bit key length and transmits it to the module.
The disclosure relates to eUICC-enabled modules that receive and manage network profiles while deriving shared keys without transmitting the secret key. The arrangement supports remote credential changes, public key infrastructure key-pair renewal, cryptographic-parameter negotiation, and profile activation. Furthermore, elliptic curve cryptography certificates and parameter sets support multiple servers or networks while maintaining compatibility with conventional wireless authentication.
Claims Coverage
The claims identify one independent claim covering four inventive features directed to secure profile distribution from a subscription manager system to a module.
Cryptographic algorithms and server keys
The subscription manager system records a digital signature algorithm comprising an elliptic curve digital signature algorithm, a server private key and corresponding server public key using elliptic curve cryptography, and a symmetric ciphering algorithm comprising an Advanced Encryption Standard with a 128-bit key length.
Module certificate, challenge, and network public key
The subscription manager system receives a certificate associated with the module that includes a module public key, receives a challenge from the module, generates a network private key and corresponding network public key, and sends the generated network public key, a digital signature generated using the server private key, and the challenge to the module.
Mutually derived shared key
The subscription manager system generates a mutually derived shared key using Elliptic Curve Diffie-Hellman based on at least the module public key and the network private key, while the module derives the shared key based on at least the associated module private key and the network public key.
Encrypted wireless-network profile delivery
The subscription manager system encrypts the profile using the symmetric ciphering algorithm and the mutually derived shared key, and sends the encrypted profile containing network access credentials for a wireless network to the module.
The independent claim combines server-side cryptographic algorithm and key recording, exchange of module and network authentication information, mutual derivation of an ECDH shared key, and symmetric encryption and delivery of a wireless-network profile.
Stated Advantages
The resulting shared network key is derived without transmitting the key.
The described arrangement enables remote credential changes.
The described arrangement is compatible with conventional wireless authentication.
The method securely distributes a profile from a subscription manager system to a module.
Compared with RSA, elliptic curve cryptography is stated to reduce key size, bandwidth, memory, processing, and power requirements.
Documented Applications
Secure distribution of an encrypted profile containing network access credentials for a wireless network from a subscription manager system to a module.
Remote changes to network credentials and compatibility with conventional wireless authentication in eUICC-enabled modules.
Delivery of eUICC profiles wherein profiles are associated with distinct key pairs.
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