FIPS 140-2 (Federal Information Processing Standards Publication 140-2) is a standard developed by the National Institute of Standards and Technology (NIST) in the United States. It defines the security requirements for cryptographic modules used in protecting sensitive information.

The FIPS 140-2 standard focuses on the security aspects of cryptographic modules, which can include both hardware and software components. It provides a framework for evaluating the security of these modules and assigning them to one of four increasing levels of security, known as Security Levels (Level 1 to Level 4).

Here's an overview of the key aspects of FIPS 140-2:

1. Security Levels: FIPS 140-2 defines four security levels, each representing an increasing level of security requirements and assurance. The security levels consider factors such as the strength of cryptographic algorithms, key management, physical security, and operational environments.

2. Cryptographic Algorithms: FIPS 140-2 specifies a list of approved cryptographic algorithms that can be used within the cryptographic modules. These algorithms include symmetric encryption, asymmetric encryption, digital signatures, hashing, and random number generation algorithms. Only approved algorithms can be used for FIPS 140-2 compliance.

3. Module Interfaces: FIPS 140-2 defines requirements for the interfaces through which cryptographic modules interact with external systems. These interfaces include input/output, key management, and self-tests. The standard provides guidelines to ensure the secure handling of sensitive information within the module.

4. Validation Process: To achieve FIPS 140-2 certification, a cryptographic module must undergo a formal testing and validation process. Accredited laboratories conduct the evaluation, following the requirements outlined in the FIPS 140-2 validation program. The testing involves assessing the module's compliance with the specified security requirements.

5. Certifications: Once a cryptographic module successfully meets the requirements of FIPS 140-2, it is granted certification by NIST. The certification indicates that the module has been evaluated and found to comply with the applicable security standards. The certified modules are listed on the NIST's Cryptographic Module Validation Program (CMVP) website.

FIPS 140-2 certification is often required or recommended for cryptographic modules used in various industries, especially in government agencies and other organizations dealing with sensitive data. It provides assurance that the cryptographic module meets specified security requirements, contributing to the overall security of information systems and communications.