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An application programming interface included with Microsoft Windows operating systems that provides services to enable developers to secure Windows-based applications using cryptography. While providing a consistent API for applications, API allows for specialized cryptographic modules (cryptographic service providers) to be provided by third parties, such as hardware security module (HSM) manufacturers. This enables applications to leverage the additional security of HSMs while using the same APIs they use to access built-in Windows cryptographic service providers. (Also known variously as CryptoAPI, Microsoft Cryptography API, MS-CAPI or simply CAPI)
NIST SP 1800-16B
NIST SP 1800-16C
NIST SP 1800-16D