Device to generate a machine specific identification key
An integrated circuit assembly having monitoring circuitry for observing the internal signals of the system so that its properties are captured. The system properties are manipulated so that they can be used as a pseudo random number and or as the basis number for an encryption key. The monitoring circuitry having: manipulation circuitry to transform monitored data and combine it with previously manipulated values; and registers to store previously manipulated values; and counters to count events; and condition detection circuitry for detecting when a signal is at a specific value or range of values. Optionally the monitoring circuitry which has the functionality for capturing system properties may be combined with other monitoring circuitry, which has the functionality required by a debug support circuit. The monitoring circuitry avoids replication of resources by sharing parts of specific monitoring circuits like counters.
1. A device for generating a machine-specific identification key, the device comprising:
a machine having a machine circuit comprising debug circuitry and at least one other machine circuit for transmitting signals, said machine having sub components;
monitoring circuitry incorporated in said debug circuitry, for monitoring said transmitted signals and for generating signal information based on said monitored signals;
a register in which said generated signal information is stored; and
means for converting said generated signal information into a machine-specific identification key;
whereby said monitoring circuitry incorporated in said debug circuitry monitors transmitted signals within said at least one other machine circuit and generates said signal information to be converted into said machine-specific identification key by said means for converting said generated signal information into a machine specific identification key; and
wherein said monitoring circuitry of said debug circuitry is re-used to monitor digital logic signal values present in said sub components of said machine.
2. A device according to claim 1 , further comprising:
key generation circuitry which uses time-stable portions of said generated signal information to generate said machine-specific identification key.
3. A device according to claim 2 , wherein:
said key generation circuitry includes a system timer; and wherein said key generation circuitry periodically generates new machine-specific identification keys based on a value of said system timer.
4. A device according to claim 3 , further comprising:
encryption related circuitry which generates an encryption key based on a resulting value of said register.
5. A device according to claim 1 , wherein:
said monitoring circuitry includes condition detection circuitry, said condition detection circuitry preventing said monitoring circuitry from changing said signal information stored in said register.
6. A device according to claim 1 , further comprising:
a data bus assembly, wherein said monitoring circuitry monitors said data bus assembly.
7. A device according to claim 1 , wherein said means for converting said generated signal information performs a hash operation on said generated signal information stored in said register.
8. A device according to claim 7 , wherein said hash operation is a bitwise exclusive-or operation.
9. A device according to claim 1 , further comprising:
means for determining a change in a monitored value.