Word-individual key generation

• US 20060265563A1
• Filed: 03/30/2006
• Published: 11/23/2006
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Gammel, Berndt, Goettfert, Rainer, Sonnekalb, Steffen, Elbe, Astrid
• Granted Patent: US 7,451,288 B2
• Time in Patent Office: Days
• US Class Current: 711/164
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00

Abstract

Apparatus and method for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units. The apparatus includes a calculator for calculating a page pre-key based on a page address, a determiner for determining the individual key based on the page pre-key and a unit address, a memory for storing the calculated page pre-key, and a checker for checking whether during a next access to a further predetermined unit to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address, and, if so, transmitting the already calculated page pre-key to the determiner by bypassing the calculator, and, if not, transmitting the page address of the further unique address to the calculator.

Claims

1. An apparatus for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable unit belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising:

a calculator for calculating a page pre-key based on the page address;

a determiner for determining the individual key based on the page pre-key and the unit address;

a memory for storing the calculated page pre-key; and

a checker for checking whether during a next access to a further predetermined unit to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address, and, if this is the case, transmitting the already calculated page pre-key to the determiner by bypassing the calculator, and, if this is not the case, transmitting the page address of the further unique address to the calculator.

2. The apparatus according to claim 1, wherein the calculator for calculating the page pre-key comprises more chip area and/or more processing run time than the determiner for determining the individual key.

3. The apparatus according to claim 1, wherein the calculator comprises a cipherer for ciphering the page address or a data block derived from the same with a master key to obtain the page pre-key.

4. The apparatus according to claim 3, wherein the cipherer comprises an expander for expanding the page address to obtain an expanded data block by mapping every bit of the page address to at least one different bit of the expanded data block, and mapping at least one bit of the page address to at least two bits of the expanded data block, and wherein the cipherer is adapted to cipher the expanded data block.

5. The apparatus according to claim 1, wherein the determiner for determining the individual key comprises an XOR gate for XORing bits of the unit address bit by bit with predetermined bits of the page pre-key to obtain the individual key.

6. The apparatus according to claim 1, wherein the determiner for determining the individual key further comprises:

a look-up table with masking vectors, each of the masking vectors being associated with a possible unit address;

a look-up unit for looking up in the look-up table with the unit address as index to obtain the associated masking vector; and

an XOR gate for XORing the masking vector and the page pre-key bit by bit to obtain the individual key.

7. The apparatus according to claim 1, wherein the determiner for determining the individual key comprises a controllable permuter for permuting bits of the page address according to a permutation regulation depending on the unit address to obtain the individual key.

8. The apparatus according to claim 1, wherein the determiner for determining the individual key comprises a selector for selecting bits of the page address according to a selection regulation depending on the unit address to obtain the individual key.

9. The apparatus according to claim 1, wherein the determiner for determining the individual key comprises:

a deriver for deriving several round keys from the page pre-key; and

a definer for defining an order among the round keys to obtain a sequence of round keys, wherein the order depends on the unit address and the sequence represents the individual key.

10. A system comprising:

an apparatus for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable unit belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising;

a calculator for calculating a page pre-key based on the page address;

a determiner for determining the individual key based on the page pre-key and the unit address;

a memory for storing the calculated page pre-key; and

a checker for checking whether during a next access to a further predetermined unit to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address, and, if this is the case, transmitting the already calculated page pre-key to the determiner by bypassing the calculator, and, if this is not the case, transmitting the page address of the further unique address to the calculator; and

an apparatus for decrypting an encrypted memory content in the predetermined addressable unit based on the individual key.

11. A system comprising:

an apparatus for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated to the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable unit belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising;

a calculator for calculating a page pre-key based on the page address;

a determiner for determining the individual key based on the page pre-key and the unit address;

a memory for storing the calculated page pre-key; and

a checker for checking whether during a next access to a further predetermined unit to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address, and, if this is the case, transmitting the already calculated page pre-key to the determiner by bypassing the calculator, and, if this is not the case, transmitting the page address of the further unique address to calculator; and

an apparatus for encrypting data to be stored based on the individual key and writing the encrypted data to be written into the predetermined addressable unit.

12. A method for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable unit belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising:

calculating a page pre-key based on the page address in a calculator;

determining the individual key based on the page pre-key and the unit address in a determiner;

temporarily storing the calculated page pre-key in a memory for temporary storage; and

checking whether during a next access to a further predetermined unit, to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address;

if an already calculated page pre-key exists, transmitting the already calculated page pre-key to the determiner by bypassing the calculator; and

if no already calculated page pre-key exists, transmitting the page address of the further unique address to the calculator.

13. An apparatus for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable units belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising:

a calculator for calculating a page pre-key based on the page address; and

a determiner for determining the individual key based on the page pre-key and the unit address,

wherein the determiner for determining the individual key comprises;

a deriver for deriving several round keys from the page pre-key; and

a definer for defining an order among the round keys to obtain a sequence of the round keys, wherein the sequence depends on the unique address and the order represents the individual key.

14. A method for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable units belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising the steps of:

calculating a page pre-key based on the page address in a calculator; and

determining the individual key based on the page pre-key and the unit address in a determiner,

wherein the step of determining the individual key comprises the following substeps;

deriving several round keys from the page pre-key; and

defining an order among the round keys to obtain a sequence of the round keys, wherein the sequence depends on the unique address and the order represents the individual key.

15. A computer program with a program code for performing a method for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable unit belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, the method comprising the steps of:

calculating a page pre-key based on the page address in a calculator;

determining the individual key based on the page pre-key and the unit address in a determiner;

temporarily storing the calculated page pre-key in a memory for temporary storage; and

checking whether during a next access to a further predetermined unit, to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address;

if an already calculated page pre-key exists, transmitting the already calculated page pre-key to the determiner by bypassing the calculator; and

if no already calculated page pre-key exists, transmitting the page address of the further unique address to the calculator,

when the computer program runs on a computer.

16. A computer program with a program code for performing the method for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable units belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, the method comprising the steps of:

calculating a page pre-key based on the page address in a calculator; and

determining the individual key based on the page pre-key and the unit address in a determiner,

wherein the step of determining the individual key comprises the following substeps;

deriving several round keys from the page pre-key; and

defining an order among the round keys to obtain a sequence of the round keys, wherein the sequence depends on the unique address and the order represents the individual key,

when the computer program runs on a computer.

17. An apparatus for generating an individual key for accessing a predetermined addressable unit of a memory divided into addressable units, wherein the addressable units are combined into pages in groups, wherein a unique address is associated with the predetermined addressable unit, which is made up of a page address indicating the page to which the addressable unit belongs, and a unit address identifying the addressable unit among the other addressable units belonging to the page, comprising:

a calculating means for calculating a page pre-key based on the page address;

a determining means for determining the individual key based on the page pre-key and the unit address; and

a memory means for storing the calculated page pre-key; and

a checking means for checking whether during a next access to a further predetermined unit to which a further unique address is associated, an already calculated page pre-key exists in a temporary memory, which has been calculated based on a page address of a unique address, which is identical to the page address of the further unique address, and, if this is the case, transmitting the already calculated page pre-key to the determining means by bypassing the calculating means, and, if this is not the case, transmitting the page address of the further unique address to the calculating means.