Method for providing blind access to an encryption key

• US 5,564,106 A
• Filed: 03/09/1995
• Issued: 10/08/1996
• Est. Priority Date: 03/09/1995
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Puhl, Larry C., Dabbish, Ezzat A., Finkelstein, Louis D.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Laufer, Pinchus M.
• Application Number:
  US08/401,592
• Time in Patent Office: 579 Days
• Field of Search: 380/21, 380/45, 380/9, 380/49
• US Class Current: 380/286
• CPC Class Codes: H04L 9/0833 involving conference or group key network architectures or network communication protocols for key management in group communication in a packet data network H04L63/065

Abstract

Blind access (100, 300, 400) to a desired encryption key of a predetermined first group member is provided to a second group. The first group encrypts a plurality of first group member encryption keys using a predetermined algorithm and transfers to the second group, the encrypted plurality of first group member encryption keys with corresponding unencrypted first group member identification fields, IDs, and a list of IDs corresponding to the first group members. The desired ID-free encryption key is selected and encrypted by the second group using a predetermined algorithm. The doubly encrypted key is transferred to the first group, decrypted by the first group and transferred to the second group for decryption. Thus, the encryption key is provided without knowledge to the first group of which member'"'"'s encryption key is being examined and with knowledge to the second group of only the desired encryption key.

Claims

1. A method for providing, to a second group, blind access to an encryption key of a predetermined first group member, comprising the steps of:

1A) encrypting, by the first group, a plurality of first group member encryption keys using a predetermined algorithm and transferring, to the second group, the encrypted plurality of first group member encryption keys with corresponding unencrypted first group member identification fields, IDs, and a list of IDs corresponding to the first group members;

1B) selecting an encryption key from the encrypted plurality of first group member encryption keys in accordance with an ID corresponding to the predetermined member of the first group;

1C) encrypting, by the second group, the selected encryption key using the predetermined algorithm and transferring, to the first group, a doubly encrypted ID-free encryption key;

1D) decrypting, by the first group, the doubly encrypted ID-free encryption key to obtain a singly encrypted key and transferring the singly encrypted key to the second group; and

1E) decrypting, by the second group, the singly encrypted key to obtain the encryption key of the predetermined first group member.

2. The method of claim 1 wherein the predetermined member of the first group is specified in an order of a court of law.

3. The method of claim 1 wherein the predetermined algorithm is a commutative encryption algorithm.

4. The method of claim 1 wherein the transferring of step 1A is directly from the first group to the second group.

5. The method of claim 1 wherein:

5A) the transferring of step 1A includes transferring to a third group, by the first group, of the encrypted plurality of first group member encryption keys with corresponding unencrypted identification codes, IDs, and a list of IDs corresponding to the first group members; and

5B) the step of selecting of step 1B includes selecting by the third group and transferring by the third group to the second group, an encryption key from the encrypted plurality of first group member encryption keys in accordance with an ID corresponding to the predetermined member of the first group.

6. The method of claim 5 wherein the third group is a verification center/government oversight committee.

7. The method of claim 1 wherein at least one of communication and data files are generated by the first group members and at least one of the communication and data files have a corporate identity field that is utilized by the second group to determine files generated by the first group.

8. A method for blind access decrypting, by a second group, of an encryption key of a predetermined member of a first group, utilizing an encrypted plurality of first group member encryption keys, received from the first group, that has been encrypted using a predetermined commutative encryption algorithm and a list of IDs corresponding to first group members, wherein the first group member encryption keys have corresponding unencrypted first group member identification fields, IDs, comprising, by the second group, the steps of:

8A) selecting an encryption key from the encrypted plurality of first group member encryption keys in accordance with an ID corresponding to the predetermined member of the first group;

8B) encrypting the selected encryption key using the predetermined commutative encryption algorithm and transferring, to the first group, a doubly encrypted ID-free encryption key; and

8C) decrypting, upon decryption by the first group of the doubly encrypted ID-free encryption key to obtain a singly encrypted key and receipt of the singly encrypted key from the first group, the singly encrypted key to obtain the encryption key of the predetermined member of the first group.

9. The method of claim 8 wherein the predetermined member of the first group is specified in an order of a court of law.

10. The method of claim 8 wherein at least one of:

communication and data files are generated by first group members and the communication and data files have a corporate identity field that is utilized by the second group to determine files generated by the first group.

11. A method for blind access decrypting, by a second group, of an encryption key of a predetermined member of a first group, utilizing an encrypted encryption key obtained by a third group from an encrypted plurality of first group member encryption keys provided to the third group by the first group, wherein the encrypted plurality of first group member encryption keys has been encrypted using a predetermined commutative encryption algorithm and the third group has preselected the encrypted encryption key as the encrypted encryption key of the predetermined member of the first group based on a list of first group member unencrypted identification fields, IDs, corresponding to first group members, comprising, for the second group, the steps of:

11A) encrypting the encrypted encryption key using the predetermined commutative encryption algorithm and transferring, to the first group, a doubly encrypted ID-free encryption key;

11B) decrypting, upon receipt of a singly encrypted key obtained by decryption by the first group of the doubly encrypted ID-free encryption key, the singly encrypted key to obtain the encryption key of the predetermined member of the first group.

12. The method of claim 11 wherein the predetermined member of the first group is specified in an order of a court of law.

13. The method of claim 11 wherein at least one of:

communication and data files are generated by first group members and the communication and data files have a corporate identity field that is utilized by the second group to determine files generated by the first group.