Method for Securing Electronic Device Data Processing

Abstract

A method for securing electronic device processes against attacks (e.g. side channel attacks) during the processing of sensitive and/or confidential data by a Central Processing Unit (CPU) to the volatile memory (e.g. RAM) of an electronic device such as, for example, a smart card, a PDA or a cellular phone is described herein. The method involves the storage of the confidential data to a dynamically and randomly assigned memory location, thereby rendering more difficult the analysis and subsequently the attacks (e.g. side channel attacks).

1 . A method for storing an item of confidential data having a predetermined length, in a volatile memory, comprising the following steps:
 allocating a buffer in said volatile memory for the storage of said item of confidential data, wherein the length of said buffer is allocated based on a predetermined multiplier of the length of said item of confidential data, said multiplier being a value greater than one;   selecting a random number that is based on the predetermined multiplier and the length of the item of confidential data;   determining a memory location within said buffer that is offset from the beginning of said buffer by an amount corresponding to said random number; and   loading said item of confidential data into said buffer, beginning at said determined memory location.   
     
     
         2 . The method of  claim 1 , wherein said random number is selected from within the range of zero to the difference between the length of said buffer and said predetermined length, minus one. 
     
     
         3 . The method of  claim 1 , wherein the step of loading said item of confidential data comprises loading the data bits of said item in consecutive memory locations, starting at said determined memory location. 
     
     
         4 . A portable electronic device, comprising:
 a volatile memory; and   a processor which executes the following operations:
 allocate a buffer in said volatile memory for the storage of an item of confidential data having a predetermined length, wherein the length of said buffer is allocated based on a predetermined multiplier of the length of said item of confidential data, said multiplier being a value greater than one; 
 select a random number that is based on the predetermined multiplier and the length of the item of confidential data; 
 determine a memory location within said buffer that is offset from the beginning of said buffer by an amount corresponding to said random number; and 
 load said item of confidential data into said buffer, beginning at said determined memory location. 
   
     
     
         5 . The portable electronic device of  claim 4 , wherein said processor loads the data bits of said item in consecutive memory locations, starting at said determined memory location. 
     
     
         6 . The portable electronic device of  claim 4 , wherein said processor selects said random number from within the range of zero to the difference between the length of said buffer and said predetermined length, minus one. 
     
     
         7 . A secure electronic device for processing data received from an input/output device, said device comprising:
 an Electrically-Erasable Programmable Read-Only Memory (EEPROM) for receiving the data from the input/output device;   an input/output port for transferring the data from the input/output device to the EEPROM;   a volatile memory for transferring the data during processing, said volatile memory including a dedicated area, the length of the dedicated area being greater than the length of the data to be transferred; and   a data processing CPU configured to implement:
 a random offset determining means that determines a random offset based upon the difference between the length of the dedicated area and the length of the data to be transferred, and 
 a data transfer means that is responsive to the random offset and configured to transfer the data to the dedicated data area beginning at a memory location of the dedicated area that is determined by the offset. 
   
     
     
         8 . The secure electronic device according to  claim 7 , wherein said volatile memory is selected from the group consisting of Random Access Memory (RAM), Internal Register and Cache Memory. 
     
     
         9 . The secure electronic device according to  claim 7 , wherein the electronic device is selected from the group consisting of a smart card, a Personal Digital Assistant (PDA) and a cellular phone. 
     
     
         10 . The secure electronic device of  claim 7 , wherein said data transfer means transfers the data bits of said item to consecutive memory locations in the dedicated area, starting at said determined memory location.