Method for expanding secure kernel program memory

• US 6,397,331 B1
• Filed: 09/16/1998
• Issued: 05/28/2002
• Est. Priority Date: 09/16/1997
• Status: Expired due to Term

• Current Assignee: SafeNet Incorporated (Thales SA)
• Original Assignee: SafeNet Incorporated (Thales SA)
• Inventors: Reed, Peter, Ober, Timothy
• Primary Examiner(s): Barron, Jr., Gilberto
• Assistant Examiner(s): KABAKOFF, STEPHEN ERIC
• Application Number:
  US09/154,323
• Time in Patent Office: 1,350 Days
• Field of Search: 713/187,164-167 717/10
• US Class Current: 713/164
• CPC Class Codes: G06F 21/51 at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability
• CPC Class Codes: G06F 21/72 in cryptographic circuits
• CPC Class Codes: G06F 21/74 operating in dual or compartmented mode, i.e. at least one secure mode
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 21/82 Protecting input, output or interconnection devices
• CPC Class Codes: G06F 8/60 Software deployment

Abstract

A method of expanding a secure kernel memory area to accommodate additional software code includes the step of digitally signing the additional code by a trusted authority. The code has a digital signature to authenticate the source of the code and to control what code can be added to the secure kernel. The new code is copied into an unprotected memory where the digital signature is verified. The digital signature includes a unique integrated circuit (IC) identification number, which provides the IC manufacturer with the ability to control the secure kernel memory expansion of all or each of the ICs. If the code is authenticated via the digital signature, then those memory blocks are locked-in as protected memory and thus given “secure kernel” privileges.

Claims

1. A method of expanding secured memory into unprotected memory to define an additional secured memory area, the secured memory being expanded to accommodate storage of an extended code, the extended code being initially stored in the unprotected memory in a location which will become the additional secured memory area, the secured memory and the unprotected memory being portions of an integrated circuit, the integrated circuit having a serial number stored in a memory thereof, which comprises the steps of:

retrieving by an authorizing party the serial number stored in the memory of the integrated circuit and retrieving the extended code proposed to be stored in the requested expanded secured memory;

verifying by the authorizing party whether the extended code is acceptable to be stored in the expanded secured memory of the integrated circuit;

generating a token signal by the authorizing party and communicating the token signal to the integrated circuit, the token signal including at least a digital signature of the extended code, as computed by the authorizing party,

receiving the token signal by the integrated circuit;

parsing the token signal to separate the digital signature of the authorizing party;

verifying by the integrated circuit the digital signature of the authorizing party parsed from the token signal which, if verified, indicates that the authorizing party authorized the expansion of the secured memory by the integrated circuit; and

invoking by the integrated circuit a command to expand the secured memory so that the additional secured memory area now encompasses the location of the unprotected memory where the extended code is stored.

2. A method of expanding a secured memory as defined by claim 1, wherein the token signal further includes the serial number of the integrated circuit, and wherein the method further comprises the steps of:

parsing by the integrated circuit from the token signal returned by the authorizing party the serial number of the integrated circuit; and

verifying by the integrated circuit the serial number parsed by the token signal by comparing the parsed serial number with the serial number stored in non-volatile memory of the integrated circuit, thereby verifying whether the extended code is acceptable to be stored in the expanded secured memory of the integrated circuit.

3. A method of expanding a secure kernel memory area into an unprotected memory area, while providing security to the unprotected memory area and validating an extended code, the secure kernel memory area and the unprotected memory area forming portions of an integrated circuit, comprising the steps of:

obtaining a serial number associated with the integrated circuit by an application program;

transferring the serial number and the extended code to an authorizing party;

generating a token by the authorizing party if expansion of the secure kernel memory area is authorized, the token including at least one of the serial number, extended code, and a digital signature;

verifying that the digital signature is authentic by a secure kernel;

copying the extended code into the unprotected memory area if the digital signature is authentic;

invoking a command to expand the secure kernel memory area if the digital signature is authentic;

specifying which memory blocks are to be acquired from the unprotected memory area to expand the secure kernel memory area;

disabling further program access to those memory blocks acquired from the unprotected memory area to expand the secure kernel memory area if the digital signature is authentic;

designating those memory blocks acquired from the unprotected memory area to expand the secure kernel memory area as expanded secure kernel memory area; and

permitting the secure kernel to access the expanded secure kernel memory area.