Cryptographic API

The Cryptographic Application Programming Interface (also known variously as CryptoAPI, Microsoft Cryptography API, or simply CAPI) is an application programming interface included with Microsoft Windows operating systems that provides services to enable developers to secure Windows-based applications using cryptography. It is a set of dynamically-linked libraries that provides an abstraction layer which isolates programmers from the code used to encrypt the data.

CryptoAPI supports both public-key and symmetric key cryptography. It includes functionality for encrypting and decrypting data and for authentication using digital certificates. It also includes a cryptographically secure pseudorandom number generator function CryptGenRandom.

CryptoAPI works with a number of CSPs (Cryptographic Service Providers) installed on the machine. CSPs are the modules that do the actual work of encoding and decoding data by performing the cryptographic functions.

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 the inclusion of a number of newer algorithms that are part of the National Security Agency (NSA) [http://www.nsa.gov/ia/industry/crypto_suite_b.cfm Suite B] . It is also flexible, featuring support for plugging in custom cryptographic APIs into the CNG runtime. 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.

CNG also supports Elliptic Curve Cryptography which is also secure and uses shorter keys than RSA.Fact|date=March 2008 The CNG API integrates with the smart card subsystem by including a Base Smart Card Cryptographic Service Provider (Base CSP) module which encapsulates the smart card API. Smart card manufacturers just have to make their devices compatible with this, rather than provide a from-scratch solution.

ee also

* CAPICOM
* DPAPI
* Public-key cryptography
* Cryptographic Service Provider

External links

* [http://msdn2.microsoft.com/en-us/library/aa380256.aspx Cryptography Reference on MSDN]
* [http://www.cryptodox.com/Microsoft_CAPI Microsoft CAPI] at CryptoDox (link should be removed - excessive advertisement)