Computer system employing a split-secret cryptographic key linked to a password-based cryptographic key security scheme

• US 20020071566A1
• Filed: 12/11/2000
• Published: 06/13/2002
• Est. Priority Date: 12/11/2000
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Kurn, David Michael
• Application Number:
  US09/735,215
• Publication Number:
  US 20020071566A1
• Time in Patent Office: Days
• US Class Current: 380/281
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 63/062 for key distribution, e.g. centrally by trusted party cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes

Abstract

In computer environments where passwords are used to compute retained secrets by methods such as password-based encryption, a need often arises to update these secrets. Retaining the password value, or the keys computed from the password, would be unwise; and requiring each password owner to type in their password would be cumbersome. The present invention describes a method that allows a fully operational system to modify the retained secrets without retaining passwords or requiring human intervention.

Claims

1. A cryptographic system in a computer system, comprising:

at least one server; and

at least one secret value including a master key, the master key being split into two or more parts wherein fewer than all the parts are required for reassembling the master key, the parts being encrypted by a password-derived or token-based key, each part being associated with a password wherein the at least one server can update the master key by requiring only some of the passwords to be revealed.

2. A cryptographic system as in claim 1, wherein the master key is used for protecting sensitive information processed by the at least one server.

3. A cryptographic system as in claim 1 further comprising a database, wherein the sensitive information is stored in the database.

4. A cryptographic system as in claim 1 in which the master key is split into the two or more parts according to the Bloom-Shamir methodology.

5. A method used in a cryptographic system, comprising:

providing at least one secret value including a master key;

splitting the master key into two or more parts wherein fewer than all the parts are required for reassembling the master key; and

encrypting the parts by a password-derived or token-based key, each part being associated with a password, wherein the master key can be reassembled by requiring only some of the passwords to be revealed.

6. A method as in claim 5, wherein the master key is used for protecting sensitive information processed by a server in the cryptographic system.

7. A method as in claim 5 wherein the master key is split into the two or more parts according to the Bloom-Shamir methodology.