NIST SP800-57pt1r4.pdf

The use of cryptographic mechanisms is one of the strongest ways to provide security services for electronic applications and protocols and for data storage. The National Institute of Standards and Technology (NIST) publishes Federal Information Processing Standards (FIPS) and NIST Recommendations (which are published as Special Publications) that specify cryptographic techniques for protecting sensitive, unclassified information.
Since NIST published the Data Encryption Standard (DES) in 1977, the suite of approved standardized algorithms has been growing. New classes of algorithms have been added, such as secure hash functions and asymmetric key algorithms for digital signatures. The suite of algorithms now provides different levels of cryptographic strength through a variety of key sizes. The algorithms may be combined in many ways to support increasingly complex protocols and applications. This NIST Recommendation applies to U.S. government agencies using cryptography for the protection of their sensitive, unclassified information. This Recommendation may also be followed, on a voluntary basis, by other organizations that want to implement sound security principles in their computer systems.
The proper management of cryptographic keys is essential to the effective use of cryptography for security. Keys are analogous to the combination of a safe. If an adversary knows the combination, the strongest safe provides no security against penetration. Similarly, poor key management may easily compromise strong algorithms. Ultimately, the security of information protected by cryptography directly depends on the strength of the keys, the effectiveness of the mechanisms and protocols associated with the keys, and the protection afforded the keys. Cryptography can be rendered ineffective by the use of weak products, inappropriate algorithm pairing, poor physical security, and the use of weak protocols.
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