Re: round and round they go, keys in ram are ripe for picking...

[Michael Holstein <michael.holstein () csuohio edu>]

> Countermeasures and their Limitations

FIPS 140-1 [http://www.itl.nist.gov/fipspubs/fip140-1.htm] addresses this.

[snip]

*SECURITY LEVEL 4*

In addition to the requirements for Security Levels 1, 2 and 3, the 
following requirements shall also apply to a multiple-chip embedded 
cryptographic module for Security Level 4.

    * The contents of the module shall be completely contained within a
      tamper detection envelope (e.g., a flexible mylar printed circuit
      with a serpentine geometric pattern of conductors or a wire- wound
      package or a non-flexible, brittle circuit) which will detect
      tampering by means such as drilling, milling, grinding or
      dissolving of the potting material or cover.

    * The module shall contain tamper response and zeroization
      circuitry. The circuitry shall continuously monitor the tamper
      detection envelope for tampering, and upon the detection of
      tampering, shall immediately zeroize all plaintext cryptographic
      keys and other unprotected critical security parameters (see
      Section 4.8.5). The circuitry shall be operational whenever
      plaintext cryptographic keys or other unprotected critical
      security parameters are contained within the cryptographic module.

    * The module shall either include environmental failure protection
      (EFP) features or undergo environmental failure testing (EFT) as
      specified in Section 4.5.4.

[snip]

Consider the IBM 4758 
[http://www-03.ibm.com/security/cryptocards/pcicc/overproduct.shtml] as 
a good example of how it's implemented.

Cheers,

Michael Holstein CISSP GCIA
Cleveland State University

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