FIPS 140 - Security Levels

Security Levels

FIPS 140-2 defines four levels of security, simply named "Level 1" to "Level 4". It does not specify in detail what level of security is required by any particular application.

• FIPS 140-2 Level 1 the lowest, imposes very limited requirements; loosely, all components must be "production-grade" and various egregious kinds of insecurity must be absent.
• FIPS 140-2 Level 2 adds requirements for physical tamper-evidence and role-based authentication.
• FIPS 140-2 Level 3 adds requirements for physical tamper-resistance (making it difficult for attackers to gain access to sensitive information contained in the module) and identity-based authentication, and for a physical or logical separation between the interfaces by which "critical security parameters" enter and leave the module, and its other interfaces.
• FIPS 140-2 Level 4 makes the physical security requirements more stringent, and requires robustness against environmental attacks.

In addition to the specified levels, Section 4.1.1 of the specification describes additional attacks that may require mitigation, such as differential power analysis. If a product contains countermeasures against these attacks, they must be documented and tested, but protections are not required to achieve a given level. Thus, a criticism of FIPS 140-2 is that the standard gives a false sense of security at Levels 2 and above because the standard implies that modules will be tamper-evident and/or tamper-resistant, yet modules are permitted to have side channel vulnerabilities that allow simple extraction of keys.