Tamper resistance of a digital data processing unit

A system for increasing a tamper resistance of a digital data processing device for cryptographically processing, comprising:

• means for computing at least one first value,
• means for inserting the at least one first value into first digital data to form second digital data, the at least one first value for verifying a look-up table of look-up tables in a look-up table network, the look-up tables operatively coupling each other, the at least one first value causing the processing device to look up a predefined entry of the at least one look-up table when processing the second digital data having the at least one first value, and
• a transmitter for distributing the second digital data having the at least one first value to the processing device to verify the at least one look-up table in the look-up table network of the look-up tables by enforcing the processing device to look up the predefined entry of the at least one look-up table based on the at least one first value inserted in the first digital data and comparing an output of the processing device with a reference value.

A system for increasing a tamper resistance of a digital data processing device, comprising:

• means for cryptographically processing first digital data using one or more first values looked up in at least one look-up table;
• a memory for storing a bit representation of software to be executed by the means for cryptographically processing first digital data at a memory address, the memory address being shared by at least part of the bit representation of the software and at least part of the at least one look-up table used by the means for cryptographically processing first digital data such that the at least part of the bit representation of the software is equal to the at least part of the at least one look-up table;
• where the first digital data contains at least one second value for verifying the at least one look-up table, the at least one second value causing the means for cryptographically processing first digital data to look up a predefined entry of the at least one look-up table when processing the first digital data.

A method for increasing a tamper resistance of a digital data processing device, comprising:

• cryptographically processing, by a processor, incoming first digital data using one or more first values looked up in at least one look-up table based on at least one second value in the first digital data;
• storing in a memory a bit representation of software to be executed by the processor at a memory address, the memory address being shared by at least part of the bit representation of the software and at least part of the at least one look-up table used by the processor such that the at least part of the bit representation of the software is equal to the at least part of the at least one look-up table;
• where the first digital data contains at least one second value for verifying the at least one look-up table, the at least one second value causing the processor to look up a predefined entry of the at least one look-up table when processing the first digital data.