FIPS 140-2
By National Institute of Standards and Technology
S. government standard specifying security requirements for cryptographic modules, the hardware or software components that perform encryption, key management, and related cryptographic operations.
Definition
FIPS 140-2 is a U.S. government standard specifying security requirements for cryptographic modules, the hardware or software components that perform encryption, key management, and related cryptographic operations. It defines four increasing security levels covering aspects like physical tamper resistance and role-based authentication, and validation is performed by accredited independent laboratories under the Cryptographic Module Validation Program, jointly run by NIST and Canada's Communications Security Establishment.
Overview
FIPS 140-2 exists because cryptography is only as trustworthy as its implementation, and a cryptographic algorithm proven secure in theory can still be undermined by a flawed module design, weak key management, or inadequate physical protection. U.S. federal agencies needed an assurance mechanism confirming that a specific cryptographic product, not just the algorithm it uses, met defined implementation and operational security requirements before being trusted to protect sensitive government data. Mechanically, the standard defines requirements across several areas, including cryptographic module specification, roles and authentication, physical security, and self-tests, organized into four increasing security levels. Level 1 requires only that approved algorithms be used correctly, with no specific physical protection requirements, suiting software-only implementations. Higher levels add requirements such as tamper-evident coatings, role-based operator authentication, and, at the highest level, tamper-responsive mechanisms that can actively zeroize keys if physical intrusion is detected, suiting hardware security modules protecting the most sensitive keys. Validation testing is conducted by accredited third-party laboratories, and NIST maintains a public registry of validated modules. FIPS 140-2 differs from Common Criteria in scope: it validates cryptographic modules specifically against a fixed technical specification, while Common Criteria evaluates broader product categories against flexible, customizable Protection Profiles, and the two are sometimes combined when a product's cryptographic component needs FIPS validation alongside a broader Common Criteria evaluation of the whole product. It differs from a protocol standard like TLS in that TLS defines how secure communication happens at a protocol level, while FIPS 140-2 validates whether the underlying cryptographic implementation performing TLS's encryption meets government assurance requirements. In practice, vendors selling cryptographic hardware or software into U.S. federal government or regulated industries, such as hardware security modules, VPN appliances, and encryption libraries, obtain FIPS 140-2 validation to satisfy procurement requirements. Many cloud providers offer a FIPS-validated cryptographic module option specifically so government customers and regulated enterprises can configure services to rely only on validated cryptography rather than the provider's default implementation. An important limitation is that FIPS validation is version-specific: even a minor code change to a validated module can require re-validation, creating friction for software that updates frequently, which is one reason many products maintain a separately versioned FIPS mode alongside their general release. The standard has also been succeeded in newer procurement by FIPS 140-3, an updated revision aligning more closely with international standards, though many existing validations under 140-2 remain referenced and relevant during the transition period.
Key Concepts
- Defines four increasing security levels for cryptographic modules
- Covers module specification, authentication, physical security, and self-tests
- Validated by accredited labs under the Cryptographic Module Validation Program
- Jointly administered by NIST and Canada's Communications Security Establishment
- Maintains a public registry of validated cryptographic modules
- Required for many U.S. federal government cryptography procurements
- Distinct from algorithm-level standards, focusing on implementation assurance
- Being succeeded by FIPS 140-3 as the updated validation standard