Exporting Cryptographic Keys

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4/8/2010

There are two occasions when it is necessary to export keys from the more secure Cryptographic Service Provider (CSP) environment—into a key BLOB:

To save a session key for use by an application.
For example, if your application encodes a database file, and you want your application to decode it later, then your application must store the session key. This is necessary because CSPs do not preserve symmetric keys between sessions.
To send a key to someone.
It would be much easier for your application if the respective CSPs could communicate directly, but they cannot. This means that the key must be exported from your CSP, transmitted by your application to the destination application, and then imported to the destination CSP.

The following table lists the functions you can use to create, configure, and destroy cryptographic keys, and to exchange them with other users.

Function	Description
CryptDestroyKey	Destroys a key.
CryptExportKey	Exports a key from a CSP into a key BLOB in the application memory space.
CryptGenRandom	Generates random data, usually for salt values.
CryptGetKeyParam	Retrieves key parameters.
CryptGetUserKey	Gets a handle to the key exchange or signature key.
CryptImportKey	Imports a key from a key BLOB into a CSP.
CryptSetKeyParam	Specifies key parameters.

See Also