Definition of CryptoAPI in the Network Encyclopedia.
What is CryptoAPI?
CryptoAPI is a core component of the latest versions of Microsoft Windows that provides application programming interfaces (APIs) for cryptographic security services that provide secure channels and code signing for communication between applications.

CryptoAPI provides a set of standard Win32 libraries for managing cryptographic functions using a single consistent interface independent of the underlying cryptographic algorithms and ciphers. CryptoAPI interfaces with modules called cryptographic service providers (CSPs), such as the Microsoft RSA Base Cryptographic Provider, to provide cryptography functions such as hashing, data encryption and decryption, key generation and exchange, digital signature issuance and verification, and so forth.
CryptoAPI is natively supported by the latest versions of Windows NT, Windows 98, and Windows 2000. Microsoft Internet Explorer version 4 provides CryptoAPI support for Windows 95. The current version of CryptoAPI is version 2.
CNG – Cryptography API: Next Generation
Windows Vista features an update to the Crypto API known as Cryptography API: Next Generation (CNG). It has better API factoring to allow the same functions to work using a wide range of cryptographic algorithms and includes a number of newer algorithms that are part of the National Security Agency (NSA) Suite B. It is also flexible, featuring support for plugging custom cryptographic APIs into the CNG runtime. However, CNG Key Storage Providers still do not support symmetric keys. CNG works in both user and kernel mode, and also supports all of the algorithms from the CryptoAPI. The Microsoft provider that implements CNG is housed in Bcrypt.dll.