CryptExportPublicKeyInfo

The CryptExportPublicKeyInfo function exports the public key information associated with the provider's corresponding private key.

#include <wincrypt.h>
BOOL WINAPI CryptExportPublicKeyInfo(
  HCRYPTPROV hCryptProv,        // in
  DWORD dwKeySpec,              // in
  DWORD dwCertEncodingType,     // in
  PCERT_PUBLIC_KEY_INFO pInfo,  // out
  DWORD *pcbInfo                // in, out
);

Parameters

hCryptProv
Specifies the Cryptographic Service Provider to use when exporting the public key information.
dwKeySpec
Identifies the public key to use from the provider's container. For example, AT_KEYEXCHANGE or AT_SIGNATURE.
dwCertEncodingType
The type of encoding used on the certificate. Currently defined certificate encoding types are shown in the following table:
Encoding type Value
X509_ASN_ENCODING 0x00000001

pInfo
Pointer to a buffer that receives the public key information to be exported.

This parameter can be NULL to set the size of this information for memory allocation purposes. For more information, see Common In/Out Parameter Conventions.

pcbInfo
Pointer to a DWORD that contains the size, in bytes, of the buffer pointed to by the pInfo parameter. When the function returns, the variable pointed to by the pcbInfo parameter contains the number of bytes stored in the buffer. This parameter can be NULL, only if pInfo is NULL.

Note  When processing the data returned in the buffer, applications need to use the actual size of the data returned. The actual size may be slightly smaller than the size of the buffer specified on input. (On input, buffer sizes are usually specified large enough to insure that the largest possible output data will fit in the buffer.) On output, the variable pointed to by this parameter is updated to reflect the actual size of the data copied to the buffer.

Return Values

TRUE if the function succeeded, FALSE if the function failed.

Call GetLastError to see the reason for any failures. Note that errors from the called functions CryptGetUserKey and CryptExportKey may be propagated to this function. This function has the following error codes.

Error code Description
CRYPT_E_OSS_ERROR Public key ASN.1 encoding error. Note, to get the OSS error subtract CRYPT_E_OSS_ERROR from the returned error and see asn1code.h for details on the error.
ERROR_MORE_DATA If the buffer specified by the pInfo parameter is not large enough to hold the returned data, the function sets the ERROR_MORE_DATA code, and stores the required buffer size, in bytes, into the variable pointed to by pcbInfo.
ERROR_FILE_NOT_FOUND Invalid certificate encoding type. Currently only X509_ASN_ENCODING is supported.

Example

See Certificate Request Example Code.

QuickInfo

  Windows NT: Requires version 4.0 SP3 or later. Available also in IE 3.02 and later.
  Windows: Requires Windows 98 (or Windows 95 with IE 3.02 or later).
  Windows CE: Unsupported.
  Header: Declared in wincrypt.h.
  Import Library: Use crypt32.lib.

See Also

CryptImportPublicKeyInfo