CRYPT_KEY_PROV_INFO

This structure contains fields that are passed as the arguments to the CryptAcquireContext function to acquire a handle to a particular key container within a particular cryptographic service provider (CSP) or to create or destroy a key container.

typedef struct _CRYPT_KEY_PROV_INFO {
LPWSTR pwszContainerName;
LPWSTR pwszProvName;
DWORD dwProvType;
DWORD dwFlags;
DWORD cProvParam;
PCRYPT_KEY_PROV_PARAM rgProvParam;
DWORD dwKeySpec;
} CRYPT_KEY_PROV_INFO,  *PCRYPT_KEY_PROV_INFO;

Members

• pwszContainerName
  String naming a key container within a particular CSP.

• pwszProvName
  String that names a CSP.

• dwProvType
  CSP type. The dwProvType values are as follows:

  PROV_RSA_FULL

  PROV_RSA_SIG

  PROV_DSS

  PROV_FORTEZZA

  PROV_MS_EXCHANGE

  PROV_SSL

  PROV_RSA_SCHANNEL

  PROV_DSS_DH

  PROV_DH_SCHANNEL

dwFlags

Values indicating whether a key container is to be created or destroyed and whether an application is allowed access to a key container.

The following flags are defined and must not collide with any CryptAcquireContext function dwFlags definitions.

See the CryptAcquireContext function for the list of the flags passed through. The flags listed in the previous table are cleared before the CryptAcquireContext function is called. The cryptographic functions CryptDecryptMessage, CryptSignMessage, CryptDecryptAndVerifyMessageSignature, and CryptSignAndEncryptMessage internally perform CryptAcquireContext operations using CRYPT_KEY_PROV_INFO from a certificate. When the CERT_SET_KEY_CONTEXT_PROP_ID or CERT_SET_KEY_PROV_HANDLE_PROP_ID flag is set, these cryptographic functions then can call CertSetCertificateContextProperty (CERT_KEY_CONTEXT_PROP_ID). This call enables the handle to the key provider to be kept open for subsequent calls to the cryptographic functions mentioned that use that same certificate, which eliminates the need to perform another CryptAcquireContext, improving efficiency. Also, because some providers can require that a password be entered for calls to CryptAcquireContext, it is desirable for applications to minimize the number of CryptAcquireContext calls made. Handles to key providers that were kept open are automatically released when the store is closed.

For example, consider an e-mail application where five encrypted messages have been received, all encrypted with the public key from the same certificate. If the handle to the key provider is kept open after the first message is processed, calls to CryptAcquireContext are not required for the four remaining messages.

• cProvParam
  Number of elements in the rgProvParam array.
• rgProvParam
  Array of pointers to CRYPT_KEY_PROV_PARAM structures.
• dwKeySpec
  Specification of the private key to retrieve. The following dwKeySpec values are defined for the default provider.

  Value	Description
  AT_KEYEXCHANGE	Keys used to encrypt/decrypt session keys.
  AT_SIGNATURE	Keys used to create and verify digital signatures.

Requirements

Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

See Also

CertGetCertificateContextProperty, CertSetCertificateContextProperty, CryptAcquireContext, CRYPT_KEY_PROV_PARAM

 Last updated on Tuesday, July 13, 2004

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