Managing Keys for Encrypted Shared Documents

• US 20100325732A1
• Filed: 06/19/2009
• Published: 12/23/2010
• Est. Priority Date: 06/19/2009
• Status: Active Grant

• Current Assignee: Valtrus Innovations Limited (f/k/a Dolya Holdco 9 Limited) (Key Patent Innovations Limited)
• Original Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Inventors: MITTAL, Hemant, Nadiminti, Syama Sundararao, Wang, Sue Pei
• Granted Patent: US 9,031,876 B2
• Time in Patent Office: Days
• US Class Current: 726/26
• CPC Class Codes: G06F 21/604 Tools and structures for managing or administering access control systems
• CPC Class Codes: G06Q 2220/10 Usage protection of distributed data files
• CPC Class Codes: G06Q 2220/12 Usage or charge determination
• CPC Class Codes: H04L 63/065 for group communications cryptographic mechanisms or cryptographic arrangements for key management involving conference or group key H04L9/0833
• 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 9/0833 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

A system administrator, while logged into a system-administrator account, creates and configures a key-administrator account and a member account. A key administrator, while logged into said key-administrator account, creates a group private key, a group public key, and a group symmetric key, a member private key, and a member public key. The key administrator encrypts the group private key with the group symmetric key, and encrypts said group symmetric key with the member public key. A publisher encrypts a document using the group public key. The publisher distributes the resulting encrypted group document so that it is accessible via said member account but not through said key-administrator account.

Claims

1. A method comprising:

a system administrator, while logged into a system-administrator account, creating and configuring a key-administrator account and a member account;

a key administrator, while logged into said key-administrator account

creating a group private key, a group public key, and a group symmetric key, a member private key, and a member public key, and

encrypting said group private key with said group symmetric key and said group symmetric key with said member public key; and

a publisher encrypting a document using said group public key and distributing the resulting encrypted group document so that it is accessible via said member account but not through said key-administrator account.

2. A method as recited in claim 1 further comprising a member, while logged into said member account, decrypting said group symmetric key with said member private key, decrypting said group private key using said group symmetric key, and decrypting said document using said group private key.

3. A method as recited in claim 1 wherein:

said creating involves creating a user symmetric key, and

said encrypting involves encrypting a copy of said user private key with said user symmetric key, and encrypting a copy of said user symmetric key with a key-administrator public key.

4. A method as recited in claim 3 further comprising:

said key administrator using said key-administrator private key to access said member symmetric key;

said key administrator using said member symmetric key to access said member private key; and

wrapping said member private key in a temporary passphrase; and

replacing a previous passphrase-protected member private key with said member private key wrapped in said temporary passphrase.

5. A method as recited in claim 4 further comprising a member resetting said temporary passphrase to a member passphrase.

6. A method comprising:

a key administrator logging into a key manager program to access a key administrator private key;

said key administrator using said key-administrator private key to access a user symmetric key;

said key administrator using said user symmetric key to access a user private key; and

said key administrator replacing a pre-existing passphrase-protected copy of said user private key with a copy of said user private key wrapped with a temporary passphrase.

7. A method as recited in claim 6 further comprising a user resetting said temporary passphrase so that said copy of said user private key is protected with a new passphrase.

8. A method as recited in claim 7 further comprising:

said user entering said new passphrase to access said user private key;

said user using said user private key to access a group symmetric key;

said user using said group symmetric key to access a group private key; and

said user using said group private key to decrypt a document.

9. A method as recited in claim 8 wherein said using said group private key involves using said group private key to access a document encryption key, said method further involving using said document encryption key to decrypt said document.

10. A method as recited in claim 9 further comprising a publisher

encrypting said document in clear form with said document encryption key;

encrypting said document encryption key with said group public key; and

inserting the result into a header of said document.

11. A system comprising:

computer-readable storage media encoded with code defining data structures, data, and computer-executable instructions, some of said computer-executable instructions defining a key manager providing for

authenticating a key administrator,

in response to input from said key administrator, generating a group public key, a group private key, a group symmetric key, member public keys, and respective member private keys,

encrypting said group private key with said group symmetric key, encrypting respective copies of said group symmetric key with said member public keys, and

restricting said key administrator from accessing documents encrypted using said group private key.

12. A system as recited in claim 11 further comprising one or more processors for executing said instruction and said key manager.

13. A system as recited in claim 11 wherein said code defines copies of said user private keys encrypted with respective user symmetric keys, and copies of said user symmetric keys encrypted using a common key administrator public key.

14. A system as recited in claim 11 wherein said code defines a system-administrator account and a key-administrator account, said system-administrator account having access to encrypted copies of said documents but not to clear versions of said group and member private keys, said key-administrator account having at least indirect access to clear versions of said group and private keys, but not to said documents.

15. A system as recited in claim 14 wherein said code defines passphrase protected copies of said user private keys, said passphrase protected copies being resettable using said key administrator account but not using said system administrator account.

16. A system comprising:

computer-readable storage media encoded with code defining data structures, data, and computer-executable instructions, said structures including;

a member account for accessing and decrypting a document encrypted using a group public key, said decrypting involving using a group private key,

a key administrator account for generating said group private key and said group public key, encrypting said group private key with a group symmetric key, encrypting said group symmetric key with said member public key to yield an encrypted group symmetric key, and distributing said encrypted group symmetric key so that it can be accessed from said member account and used for decrypting said group private key, said key-administrator account being restricted from accessing said document; and

a system administrator account for managing said key-administrator account and said user account, said system administrator account having access to said document but not to any unencrypted copy of said group private key or to any unencrypted copy of said symmetric key.

17. A system as recited in claim 16 further comprising one or more processors for executing said instructions.

18. A system as recited in claim 16 wherein said key-administrator account provides for generating a member public key and a member private key, and encrypting said group symmetric key with said member public key.

19. A system as recited in claim 16 wherein said member account provides for accessing said user private key so that said group symmetric key can be accessed so that said group private key can be accessed so that said document can be decrypted.

20. A system as recited in claim 16 further comprising a member private key, a member public key, a member symmetric key, an administrator public key, and an administrator private key, a copy of said member private key being protected by said member symmetric key, a copy of said member symmetric key being encrypted by said key administrator public key so as to be accessible using said key administrator private key.