# US 11,445,376 B2 · Security establishment method, terminal device, and network device

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- Number: US 11,445,376 B2
- Document ID: US11445376B2
- Status: Granted
- Kind: B2
- Application number: 16/753,933
- Filed: 2018-10-10
- Published: 2020-11-12
- Granted: 2022-09-13
- Earliest claimed: 2017-10-10
- Assignees: Ntt Docomo, Inc.
- Applicants: Ntt Docomo, Inc.
- Inventors: Hiroshi Aono; Alf Zugenmaier
- Web page: https://patentgrep.com/patent/US11445376B2

## CPC

- H04W 12/06: Authentication
- H04W 12/50: Secure pairing of devices
- G09C 1/00: Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00)
- H04L 9/08: Key distribution {or management, e.g. generation, sharing or updating, of cryptographic keys or passwords (network architectures or network communication protocols for supporting key management in a packet data network H04L63/06)}
- H04L 9/3073: {involving pairings, e.g. identity based encryption [IBE], bilinear mappings or bilinear pairings, e.g. Weil or Tate pairing}
- H04L 9/32: including means for verifying the identity or authority of a user of the system {or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials}
- H04W 8/12: between location registers or mobility servers
- H04W 12/041: Key generation or derivation
- H04W 12/40: Security arrangements using identity modules
- H04W 12/43: using shared identity modules, e.g. SIM sharing
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- G09C: CIPHERING OR DECIPHERING APPARATUS FOR CRYPTOGRAPHIC OR OTHER PURPOSES INVOLVING THE NEED FOR SECRECY
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A security establishment method includes generating a pair of keys via mutual authentication between a terminal device (110) and a serving network, and the terminal device (110) and the serving network sharing KASME by using the generated pair of keys (Steps S50 and S100), the terminal device (110) and a roaming destination network of the terminal device (110) generating, by using the KASME, KSEAF mapped with SEAF (50) (Steps S140 and S150), and the terminal device (110) and the roaming destination network generating, by using at least the KSEAF and SUPI used to recognize a subscriber in the serving network, KAMF mapped with AMF (60) (Steps S140 and S150).

## Claims

### Claim 1

A security establishment method of establishing a security of a terminal device, in which a subscriber identity module used to recognize a subscriber has been mounted, by using secret information stored in the subscriber identity module and a pair of keys consisting of an encryption key and an integrity key generated based on the secret information, the security establishment method comprising:
generating the pair of keys via mutual authentication between the terminal device and a serving network;
sharing in which the terminal device and the serving network share a first temporary key by using the pair of keys generated at the generating;
acquiring in which the terminal device and a roaming destination network of the terminal device acquire a second temporary key mapped with a security anchor function of the roaming destination network, the second temporary key being generated by using the first temporary key; and
generating a third temporary key mapped with access and mobility administration function of the roaming destination network, in which the terminal device and the roaming destination network:
input, into a Key Derivation Function (KDF), the second temporary key and a subscription permanent identifier (SUPI) used to recognize the subscriber in the serving network; and
generate the third temporary key, by using at least:
the second temporary key;
the SUPI; and
information of capabilities or a feature set of the security anchor function of the roaming destination.

### Claim 2

A terminal device in which a subscriber identity module used to recognize a subscriber can be mounted, the terminal device comprising:
a first key generating unit that generates a first temporary key by using a pair of keys consisting of an encryption key and an integrity key generated based on secret information stored in the subscriber identity module;
a second key generating unit that generates, by using the first temporary key, a second temporary key mapped with a security anchor function of a roaming destination network of the terminal device; and
a third key generating unit that:
inputs, into a Key Derivation Function (KDF), the second temporary key and a subscription permanent identifier (SUPI) used to recognize the subscriber in the serving network; and
generates a third temporary key mapped with access and mobility administration function of the roaming destination network, by using at least:
the second temporary key;
the SUPI; and
information of capabilities or a feature set of the security anchor function of the roaming destination.

### Claim 3

A network device capable of performing communication with a terminal device in which a subscriber identity module used to recognize a subscriber can be mounted, the network device comprising:
a first key generating unit that generates a first temporary key by using a pair of keys consisting of an encryption key and an integrity key generated based on secret information stored in the subscriber identity module;
a second key generating unit that generates, by using the first temporary key, a second temporary key mapped with a security anchor function of a roaming destination network of the terminal device; and
a third key generating unit that:
inputs, into a Key Derivation Function (KDF), the second temporary key and a subscription permanent identifier (SUPI) used to recognize the subscriber in the serving network; and
generates a third temporary key mapped with access and mobility administration function of the roaming destination network, by using at least:
the second temporary key;
the SUPI; and
information of capabilities or a feature set of the security anchor function of the roaming destination.