Methods and systems for providing high-security cryptographic keys to mobile radios

• US 9,288,043 B1
• Filed: 10/17/2014
• Issued: 03/15/2016
• Est. Priority Date: 10/17/2014
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Mihm, Thomas J Jr., Fuchs, Kenneth C
• Primary Examiner(s): Zecher, Dede
• Assistant Examiner(s): Doan, Trang
• Application Number:
  US14/516,761
• Time in Patent Office: 515 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 9/006 involving public key infrastructure [PKI] trust models network architecture or network communication protocol for supporting authentication of entities using certificates in a packet data network H04L63/0823
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]

Abstract

At least one embodiment takes the form of a process carried out by a key-management infrastructure (KMI). The KMI receives first and second disassembly products of a high-security cryptographic key and provides the first and second disassembly products to a mobile radio for reassembly of the high-security cryptographic key. Providing the first disassembly product to the mobile radio includes providing the first disassembly product to the mobile radio over a local connection via a restricted-access key variable loader. Providing the second disassembly product to the mobile radio includes (i) generating a medium-security-encrypted second disassembly product at least in part by encrypting the second disassembly product based on at least one medium-security cryptographic key, and (ii) providing the medium-security-encrypted second disassembly product to the mobile radio over an air interface.

Claims

1. A method carried out by a key-management infrastructure, the method comprising:

receiving first and second disassembly products of a high-security cryptographic key; and

providing the first and second disassembly products to a mobile radio for reassembly of the high-security cryptographic key,

wherein providing the first disassembly product to the mobile radio comprises providing the first disassembly product to the mobile radio over a local connection via a restricted-access key variable loader, and

wherein providing the second disassembly product to the mobile radio comprises;

generating a medium-security-encrypted second disassembly product at least in part by encrypting the second disassembly product based on at least one medium-security cryptographic key; and

providing the medium-security-encrypted second disassembly product to the mobile radio over an air interface.

2. The method of claim 1, wherein:

the key-management infrastructure comprises an Association of Public-Safety Communications Officials-International (APCO) Project 25 (P25) key-management facility, and

the method being carried out by the key-management infrastructure comprises the method being carried out by the APCO P25 key-management facility.

3. The method of claim 1, wherein:

the first disassembly product comprises a random number, and

the second disassembly product is based on both the high-security cryptographic key and the random number.

4. The method of claim 3, wherein the second disassembly product comprises an XOR of the high-security cryptographic key and the random number.

5. The method of claim 1, further comprising confirming that the mobile radio is authorized to receive the high-security cryptographic key prior to completing the providing of both the first and second disassembly products to the mobile radio.

6. The method of claim 1, wherein:

the at least one medium-security cryptographic key comprises a medium-security traffic encryption key (MS-TEK), and

encrypting the second disassembly product based on the at least one medium-security cryptographic key comprises encrypting the second disassembly product based on the MS-TEK.

7. The method of claim 6, wherein:

the at least one medium-security cryptographic key further comprises a medium-security key encryption key (MS-KEK), and

encrypting the second disassembly product based on the MS-TEK comprises encrypting the second disassembly product based on both the MS-KEK and the MS-TEK.

8. The method of claim 7, wherein encrypting the second disassembly product based on both the MS-KEK and the MS-TEK comprises:

generating a first encryption result at least in part by encrypting the second disassembly product based on the MS-KEK; and

encrypting the first encryption result based on the MS-TEK.

9. The method of claim 1, wherein:

the at least one medium-security cryptographic key comprises a medium-security key encryption key (MS-KEK), and

encrypting the second disassembly product based on the at least one medium-security cryptographic key comprises encrypting the second disassembly product based on the MS-KEK.

10. The method of claim 1, wherein the high-security cryptographic key comprises a high-security key encryption key (HS-KEK).

11. The method of claim 10, further comprising:

receiving a high-security traffic encryption key (HS-TEK) that is encrypted based on the HS-KEK; and

providing the high-security-encrypted HS-TEK to the mobile radio over the air interface for decryption by the mobile radio based on the HS-KEK.

12. The method of claim 11, further comprising:

encrypting the HS-TEK based on at least one medium-security cryptographic key prior to providing the HS-TEK to the mobile radio over the air interface.

13. The method of claim 11, wherein a radio access network (RAN) comprises the key-management infrastructure, the method further comprising the RAN:

receiving inbound high-security traffic that is encrypted based on the HS-TEK;

generating medium-security-encrypted inbound high-security traffic at least in part by encrypting the received inbound high-security traffic based on at least one medium-security cryptographic key; and

forwarding the medium-security-encrypted inbound high-security traffic over the air interface to the mobile radio.

14. The method of claim 11, wherein a radio access network (RAN) comprises the key-management infrastructure, the method further comprising the RAN:

receiving medium-security-encrypted outbound high-security traffic over the air interface from the mobile radio, the outbound high-security traffic being encrypted based on the HS-TEK;

decrypting the received medium-security-encrypted outbound high-security traffic based on at least one medium-security cryptographic key; and

forwarding the outbound high-security traffic via a packet-data connection.

15. The method of claim 1, wherein the high-security cryptographic key comprises a high-security traffic encryption key (HS-TEK).

16. The method of claim 15, wherein a radio access network (RAN) comprises the key-management infrastructure, the method further comprising the RAN:

receiving inbound high-security traffic that is encrypted based on the HS-TEK;

generating medium-security-encrypted inbound high-security traffic at least in part by encrypting the received inbound high-security traffic based on at least one medium-security cryptographic key; and

forwarding the medium-security-encrypted inbound high-security traffic over the air interface to the mobile radio.

17. The method of claim 15, wherein a radio access network (RAN) comprises the key-management infrastructure, the method further comprising the RAN:

receiving medium-security-encrypted outbound high-security traffic over the air interface from the mobile radio, the outbound high-security traffic being encrypted based on the HS-TEK;

decrypting the received medium-security-encrypted outbound high-security traffic based on at least one medium-security cryptographic key; and

forwarding the outbound high-security traffic via a packet-data connection.

18. The method of claim 1, further comprising, prior to providing the medium-security-encrypted second disassembly product to the mobile radio over the air interface:

generating a storage-encrypted second disassembly product at least in part by encrypting the second disassembly product based on a storage cryptographic key;

storing the storage-encrypted second disassembly product in a cryptographic key storage;

retrieving the storage-encrypted second disassembly product from the cryptographic key storage; and

decrypting the storage-encrypted second disassembly product based on the storage cryptographic key.

19. The method of claim 1, wherein:

the mobile radio comprises a high-security hardware module, and

providing the first and second disassembly products to the mobile radio for reassembly of the high-security cryptographic key comprises providing the first and second disassembly products to the high-security hardware module.

20. A key-management infrastructure comprising:

a communication interface;

a processor; and

a non-transitory data storage medium containing instructions executable by the processor for causing the key-management infrastructure to carry out a set of functions, the set of functions including;

receiving first and second disassembly products of a high-security cryptographic key; and

providing the first and second disassembly products to a mobile radio for reassembly of the high-security cryptographic key,

wherein providing the first disassembly product to the mobile radio comprises providing the first disassembly product to the mobile radio over a local connection via a restricted-access key variable loader,

wherein providing the second disassembly product to the mobile radio comprises;

generating a medium-security-encrypted second disassembly product at least in part by encrypting the second disassembly product based on at least one medium-security cryptographic key; and

providing the medium-security-encrypted second disassembly product to the mobile radio over an air interface.