Control function implementing selective transparent data authentication within an integrated system

• US 7,266,842 B2
• Filed: 04/18/2002
• Issued: 09/04/2007
• Est. Priority Date: 04/18/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hall, William E., Rosu, Marcel-Catalin, Foster, Eric M.
• Primary Examiner(s): Moise; Emmanuel L.
• Assistant Examiner(s): Khoshnoodi; Nadia
• Application Number:
  US10/125,708
• Publication Number:
  US 20030200448A1
• Time in Patent Office: 1,965 Days
• Field of Search: 713/161, 713/151, 726/30
• US Class Current: 726/17
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: G06F 21/85 interconnection devices, e.g. bus-connected or in-line devices

Abstract

A data authentication technique is provided for a data access control function of an integrated system. The technique includes passing a data request from a functional master of the integrated system through the data access control function, and responsive to the data request, selectively authenticating requested data. The selective authentication, which can occur transparent to the functional master initiating the data request, includes employing integrity value generation on the requested data when originally stored and when retrieved, in combination with encryption and decryption thereof to ensure the authenticity of the requested data. As an enhancement, cascading integrity values may be employed to facilitate data authentication.

Claims

1. A data authentication method for an integrated device having multiple functional masters, the multiple functional masters having multiple master ids, said method comprising:

defining different levels of data access security to the multiple functional masters, where the different levels of data access security are predefined in an access table, the access table enforcing the defined access rights for the multiple functional masters to ensure security within the integrated device;

passing a data request, comprising an address associated with requested data, from a functional master through a data access control function disposed within a data path between a bus controller and a slave device coupled to memory, the data access control function residing within a secure memory subsystem of the integrated device;

responsive to the data request, selectively authenticating the requested data by the data access control function transparent to the functional master of the integrated device initiating the data request, the selectively authenticating comprising selectively verifying integrity of the requested data by the data access control function within the secure memory subsystem based on a master ID of the requesting master, the data access level for the requesting master defined in the access table and the address of the requested data, the verifying integrity employing an encrypted integrity check value comprising an encrypted digest of the requested data, the encrypted digest being an encrypted reduced version of the requested data;

when authenticating the requested data, deciding by the data access control function, with reference to the data access level of the requesting master, whether to decrypt the data when the request is a read request, and whether to encrypt the data when the request is a write request; and

wherein the verifying integrity employs a common encryption/decryption engine of the data access control function when encrypting/decrypting integrity check values as used for encrypting/decrypting the requested data.

2. The method of claim 1, wherein the selectively authenticating further comprises:

obtaining a predetermined first integrity value representative of the requested data;

employing a data address associated with the data request to read encrypted, requested data responsive to the data request;

decrypting, by the data address control function, the encrypted, requested data;

calculating a second integrity value from the decrypted requested data; and

comparing the first integrity value and the second integrity value to authenticate the requested data, and with authentication thereof, returning the requested data to the functional master initiating the data request.

3. The method of claim 2, wherein the obtaining comprises:

calculating an integrity value address from the data address associated with the data request wherein the calculating includes employing an integrity table address;

generating a request to read an encrypted integrity value from a secure integrity table; and

receiving and decrypting the read encrypted integrity value by the data access control function to obtain the first integrity value representative of the requested data.

4. The method of claim 1, further comprising receiving by the data access control function a request to write data, and wherein the selectively authenticating further comprises facilitating subsequent authentication of the write data by:

storing an encrypted version of the write data;

calculating an integrity value from the write data, and encrypting the integrity value;

calculating an integrity value address using a write data address associated with the write data; and

storing the encrypted integrity value using the calculated integrity value address.

5. The method of claim 4, wherein the selectively authenticating further comprises:

encrypting, by the data access control function, the write data of the write request and storing the encrypted write data, wherein the encrypted write data and the encrypted integrity value can both be retrieved in accordance with a subsequent read request to read requested data.

6. The method of claim 5, wherein receipt of the subsequent read request by the data access control function initiates retrieval of the encrypted requested data and the encrypted integrity value associated therewith, as well as decryption of the encrypted requested data and decryption of the encrypted integrity value for transparent authentication of the requested data prior to forwarding thereof to a functional master initiating the subsequent read request.

7. The method of claim 6, wherein the storing of the encrypted write data and the storing of the encrypted integrity value associated therewith occur such that the encrypted write data and the associated encrypted integrity value are retrievable in a single read operation.

8. The method of claim 1, wherein the selectively authenticating includes employing cascading integrity values, the cascading integrity values including at least one composite integrity value maintained by the data access control function, the at least one composite integrity value comprising an integrity value derived from other integrity values.

9. The method of claim 8, further comprising maintaining the at least one composite integrity value in persistent storage associated with the data access control function.

10. The method of claim 1, wherein the verifying integrity comprises for a read request employing a saved encrypted first integrity check value comprising a previously encrypted digest of the requested data, the previously encrypted digest being an encrypted reduced version of the requested data previously encrypted employing the same encryption/decryption engine of the data access control function as employed to encrypt the requested data itself, the verifying integrity of the requested data comprising:

retrieving and decrypting the encrypted first integrity check value, and retrieving and decrypting the encrypted requested data;

generating a second integrity check value using a same mathematical function as employed in generating the first integrity check value; and

comparing the first and second integrity check values, and if matching, the requested data is authenticated, otherwise, the requested data has been corrupted and corrective action is to be taken.

11. The method of claim 1, wherein the verifying integrity comprises for a write request:

generating a first integrity check value as a mathematically condensed version of the requested data to be secured and authenticated;

encrypting the requested data and encrypting the first integrity check value using a common encryption/decryption engine of the data access control function; and

storing the encrypted integrity check value and storing the encrypted requested data in memory, wherein encrypting the integrity check value employing the encryption/decryption engine of the data access control function simplifies integrity value calculations employed in protecting the requested data.

12. A data authentication system for an integrated device having multiple functional masters, the multiple functional master having multiple master ids, said system comprising:

means for defining different levels of data access security to the multiple functional masters, where the different levels of data access security are predefined in an access table, the access table enforcing the defined access rights for the multiple functional masters to ensure security within the integrated device;

a data access controller for receiving a data request from a functional master, the data request comprising an address associated with requested data, and the data access controller being disposed in a data path between a bus controller and a slave device coupled to memory, the data access control function residing within a secure memory subsystem of the integrated device;

means for selectively authenticating the requested data at the data access controller responsive to the data request, wherein the means for selectively authenticating is transparent to the functional master of the integrated device initiating the data request, the selectively authenticating comprising means for selectively verifying integrity of the requested data by the data access control function within the secure memory subsystem based on a master ID of the requesting master, the data access level for the requesting master defined in the access table and the address of the requested data, the means for selectively verifying integrity employing an encrypted integrity check value comprising an encrypted digest of the requested data, the encrypted digest being an encrypted reduced version of the requested data;

wherein the means for selectively authenticating comprises means for deciding by the data access controller, with reference to the data access level of the requesting master, whether to decrypt the data when the request is a read request, and whether to encrypt the data when the request is a write request; and

wherein the means for selectively verifying integrity further employs a common encryption/decryption engine of the data access control function when encrypting/decrypting integrity check values as used for encrypting/decrypting the requested data.

13. The system of claim 12, wherein the means for selectively authenticating further comprises:

means for obtaining a predetermined first integrity value representative of the requested data;

means for employing a data address associated with the data request to read encrypted, requested data responsive to the data request;

means for decrypting, by the data address controller, the encrypted, requested data;

means for calculating a second integrity value from the decrypted requested data; and

means for comparing the first integrity value and the second integrity value to authenticate the requested data, and with authentication thereof, for returning the requested data to the functional master initiating the data request.

14. The system of claim 13, wherein the means for obtaining comprises:

means for calculating an integrity value address from the data address associated with the data request, wherein the means for calculating includes means for employing an integrity table address;

means for generating a request to read an encrypted integrity value from a secure integrity table; and

means for receiving and decrypting the read encrypted integrity value by the data access controller to obtain the first integrity value representative of the requested data.

15. The system of claim 12, further comprising means for receiving by the data access controller a request to write data, and wherein the means for selectively authenticating further comprises means for facilitating subsequent authentication of the write data by:

storing an encrypted version of the write data;

calculating an integrity value from the write data, and encrypting the integrity value;

calculating an integrity value address using a write data address associated with the write data; and

storing the encrypted integrity value using the calculated integrity value address.

16. The system of claim 15, wherein the means for selectively authenticating further comprises:

means for encrypting, by the data access controller, the write data of the write request and storing the encrypted write data, wherein the encrypted write data and the encrypted integrity value can both be retrieved in accordance with a subsequent read request to read requested data.

17. The system of claim 16, wherein receipt of the subsequent read request by the data access controller initiates retrieval of the encrypted requested data and the encrypted integrity value associated therewith, as well as decryption of the encrypted requested data and decryption of the encrypted integrity value for transparent authentication of the requested data prior to forwarding thereof to a functional master initiating the subsequent read request.

18. The system of claim 17, wherein the storing of the encrypted write data and the storing of the encrypted integrity value associated therewith occur such that the encrypted write data and the associated encrypted integrity value are retrievable in a single read operation.

19. The system of claim 12, wherein the means for selectively authenticating includes means for employing cascading integrity values, the cascading integrity values including at least one composite integrity value maintained by the data access controller, the at least one composite integrity value comprising an integrity value derived from other integrity values.

20. The system of claim 19, further comprising means for maintaining the at least one composite integrity value in persistent storage associated with the data access control function.

21. The system of claim 12, wherein the means for selectively verifying integrity comprises for a read request means for employing a saved encrypted integrity check value comprising a previously encrypted digest of the requested data, the previously encrypted digest being an encrypted reduced version of the requested data previously encrypted employing the same encryption/decryption engine of the data access control function as employed to encrypt the requested data itself, the means for selectively verifying integrity of the requested data further comprising:

means for retrieving and decrypting the encrypted first integrity check value, and for retrieving and decrypting the encrypted requested data;

means for generating a second integrity check value using a same mathematical function as employed in generating the first integrity check value; and

means for comparing the first and second integrity check values, and if matching, the requested data is authenticated, otherwise, the requested data has been corrupted and corrective action is to be taken.

22. The system of claim 12, wherein the means for selectively verifying integrity comprises for a write request:

means for generating an integrity check value as a mathematically condensed version of the requested data to be secured and authenticated;

means for encrypting the requested data and encrypting the first integrity check value using a common encryption/decryption engine of the data access control function; and

means for storing the encrypted integrity check value and for storing the encrypted requested data in memory, wherein employing the encryption/decryption engine of the data access control function to encrypt the integrity check valve simplifies integrity value calculations employed in protecting the requested data.

23. At least one program storage device readable by a machine, tangibly embodying at least one program of instructions executable by the machine to perform a data authentication method for an integrated device having multiple functional masters, the multiple functional masters having multiple master ids, the method comprising:

defining different levels of data access security to the multiple functional masters, where the different levels of data access security are predefined in an access table, the access table enforcing the defined access rights for the multiple functional masters to ensure security within the integrated device;

passing a data request, comprising an address associated with requested data, from a functional master through a data access control function disposed within a data path between a bus controller and a slave device coupled to memory, the data access control function residing within a secure memory subsystem of the integrated device;

responsive to the data request, selectively authenticating the requested data by the data access control function transparent to the functional master of the integrated device initiating the data request, the selectively authenticating comprising selectively verifying integrity of the requested data by the data access control function within the secure memory subsystem based on a master ID of the requesting master, the data access level for the requesting master defined in the access table and the address of the requested data, the verifying integrity employing an encrypted integrity check value comprising an encrypted digest of the requested data, the encrypted digest being an encrypted reduced version of the requested data;

when authenticating the requested data, deciding by the data access control function, with reference to the data access level of the requesting master, whether to decrypt the data when the request is a read request, and whether to encrypt the data when the request is a write request; and

wherein the verifying integrity employs a common encryption/decryption engine of the data access control function when encrypting/decrypting integrity check values as used for encrypting/decrypting the requested data.