In the field of computer security
, a system is said to be tamper-resistant
if it is difficult to modify or subvert, even for an assailant who has physical access to the system. A common form of tamper-resistance is a device or sub-system which contains information which is difficult to extract under these circumstances.
It has been argued that it is very difficult to make simple electronic devices secure against tampering, because numerous attacks are possible,
  including :
- physical attack of various forms (drills, files, solvents, etc)
- freezing the device
- applying out-of-spec voltages or power surges
- applying unusual clock signals
- inducing software errors using radiation
has, however, challenged this argument by developing the 4758 secure cryptoprocessor
, which includes defences
against numerous mechanical, chemical, electrical, and radiological attacks. Despite some hiccups, 
it appears possible that such systems could be impenetrable to adversaries with limited time or resources.