System and method for detecting fault injection attacks

A security system configured for deployment on a chip which is to be protected, the system comprising:

• at least one fault injection detection subsystem configured for deployment on the chip, each said fault injection detection subsystem having plural sensitivity levels which are selectable in real time and comprising:
• at least one hardware fault injection detector circuit/s, configured for deployment on the chip,
• and, coupled thereto,
• fault injection detection sensitivity level control logic configured for deployment on the chip and operative, in real time, to transition the fault injection detection subsystem, from its current fault injection detection sensitivity level from among said plural selectable fault injection detection sensitivity levels, to a next fault injection detection sensitivity level from among said plural selectable fault injection detection sensitivity levels, by generating fault injection detection sensitivity control signals including fault injection detection sensitivity level selections, and feeding the fault injection detection sensitivity control signals to at least one hardware fault injection detector in the fault injection detection subsystem,
• wherein the fault injection detection subsystem has a response time comprising a time-period which elapses from an indication, comprising an opcode indicative of a required sensitivity level for the fault injection detection subsystem, which is provided to sensitivity level selection logic employed by said sensitivity level control logic, and until the fault injection detection subsystem is set at the required sensitivity level, and the chip being protected has a decode-execution cycle, for each single instruction the chip executes, and wherein said response time is shorter than said decode-execution cycle,
• wherein the plural fault injection detection sensitivity levels include:
• a first level of fault injection detection sensitivity;
• and
• a second level of fault injection detection sensitivity higher than the first level of fault injection detection sensitivity,
• and wherein the fault injection detection subsystem, when at the second, higher, of fault injection detection sensitivity level, detects more events as fault injections, than would be detected as fault injections when the system's fault injection detection sensitivity level is at the first, lower level.