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CryptExportPublicKeyInfo function

The CryptExportPublicKeyInfo function exports the public key information associated with the corresponding private key of the provider. For an updated version of this function, see CryptExportPublicKeyInfoEx.

Syntax


BOOL WINAPI CryptExportPublicKeyInfo(
  _In_     HCRYPTPROV_OR_NCRYPT_KEY_HANDLE hCryptProvOrNCryptKey,
  _In_     DWORD dwKeySpec,
  _In_     DWORD dwCertEncodingType,
  _Out_    PCERT_PUBLIC_KEY_INFO pInfo,
  _Inout_  DWORD *pcbInfo
);

Parameters

hCryptProvOrNCryptKey [in]

Handle of the cryptographic service provider (CSP) to use when exporting the public key information. This handle must be an HCRYPTPROV handle that has been created by using the CryptAcquireContext function or an NCRYPT_KEY_HANDLE handle that has been created by using the NCryptOpenKey function. New applications should always pass in the NCRYPT_KEY_HANDLE handle of a CNG CSP.

dwKeySpec [in]

Identifies the private key to use from the container of the provider. It can be AT_KEYEXCHANGE or AT_SIGNATURE. This parameter is ignored if an NCRYPT_KEY_HANDLE is used in the hCryptProvOrNCryptKey parameter.

dwCertEncodingType [in]

Specifies the encoding type used. It is always acceptable to specify both the certificate and message encoding types by combining them with a bitwise-OR operation as shown in the following example:

X509_ASN_ENCODING | PKCS_7_ASN_ENCODING

Currently defined encoding types are:

  • X509_ASN_ENCODING
  • PKCS_7_ASN_ENCODING
pInfo [out]

A pointer to a CERT_PUBLIC_KEY_INFO structure to receive the public key information to be exported.

To set the size of this information for memory allocation purposes, this parameter can be NULL. For more information, see Retrieving Data of Unknown Length.

pcbInfo [in, out]

A pointer to a DWORD that contains the size, in bytes, of the buffer pointed to by the pInfo parameter. When the function returns, the DWORD contains the number of bytes needed for the return buffer.

Note  When processing the data returned in the buffer, applications need to use the actual size of the data returned. The actual size can be slightly smaller than the size of the buffer specified on input. (On input, buffer sizes are usually specified large enough to ensure 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 value

If the function succeeds, the function returns nonzero (TRUE).

If the function fails, it returns zero (FALSE). For extended error information, call GetLastError.

Note  Errors from the called functions CryptGetUserKey and CryptExportKey might be propagated to this function.

This function has the following error codes.

Return codeDescription
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.

 

If the function fails, GetLastError may return an Abstract Syntax Notation One (ASN.1) encoding/decoding error. For information about these errors, see ASN.1 Encoding/Decoding Return Values.

Examples

For an example that uses this function, see Example C Program: Making a Certificate Request.

Requirements

Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]

Header

Wincrypt.h

Library

Crypt32.lib

DLL

Crypt32.dll

See also

Data Management Functions
CryptImportPublicKeyInfo

 

 

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