CertGetCertificateContextProperty

Article
06/30/2006

This function retrieves the information contained in an extended property of a certificate context.

BOOL WINAPI CertGetCertificateContextProperty(
PCCERT_CONTEXT pCertContext,
DWORD dwPropId,
void *pvData,
DWORD *pcbData
);

Parameters

pCertContext
[in] Pointer to the CERT_CONTEXT structure of the certificate containing the property to be retrieved.

dwPropId
[in] Identifies the property to be retrieved. The following table shows the currently defined identifiers and the data type to be returned in the pvData parameter.

Property identified	pvData type	Description
CERT_ACCESS_STATE_PROP_ID	DWORD	Returns a DWORD value indicating whether write operations to the certificate are persisted. The DWORD value is not set if the certificate is in a memory store or in a registry-based store that is opened as read-only.
CERT_ARCHIVED_PROP_ID	NULL	Indicates the certificate is skipped during enumerations. A certificate with this property set is found with explicit search operations, such as those used to find a certificate with a specific hash or a serial number. No data in pvData is associated with this property.
CERT_AUTO_ENROLL_PROP_ID	Array of BYTEs	Returns a NULL-terminated Unicode string naming the certificate type for which the certificate has been auto enrolled.
CERT_DESCRIPTION_PROP_ID	Array of BYTEs	Returns the property displayed by the certificate UI. This property allows the user to describe the certificate's use.
CERT_ENHKEY_USAGE_PROP_ID	Array of BYTEs	Returns an array of bytes containing an ASN.1 encoded CERT_ENHKEY_USAGE structure. This structure contains an array of enhanced key usage OIDs, each specifying a valid use of the certificate.
CERT_FRIENDLY_NAME_PROP_ID	Array of BYTEs	Returns a NULL-terminated Unicode character string specifying the friendly name for the certificate.
CERT_HASH_PROP_ID	Array of BYTEs	Returns the SHA1 hash. If the hash does not exist, it is computed using the CryptHashCertificate function.
CERT_KEY_CONTEXT_PROP_ID	CERT_KEY_CONTEXT	Returns a CERT_KEY_CONTEXT structure.
CERT_KEY_IDENTIFIER_PROP_ID	Array of BYTEs	If nonexistent, searches for the szOID_SUBJECT_KEY_IDENTIFIER extension. If that fails, a SHA1 hash is done on the certificate's SubjectPublicKeyInfo to produce the identifier values.
CERT_KEY_PROV_HANDLE_PROP_ID	HCRYPTPROV	Returns the provider handle obtained from CERT_KEY_CONTEXT_PROP_ID.
CERT_KEY_PROV_INFO_PROP_ID	CRYPT_KEY_PROV_INFO	Returns a pointer to CRYPT_KEY_PROV_INFO.
CERT_KEY_SPEC_PROP_ID	DWORD	Returns a DWORD value specifying the private key obtained from CERT_KEY_CONTEXT_PROP_ID if it exists. Otherwise, if CERT_KEY_PROV_INFO_PROP_ID exists, it is the source of the dwKeySpec.
CERT_MD5_HASH_PROP_ID	Array of BYTEs	Returns the MD5 hash. If the hash does not exist, it is computed using the CryptHashCertificate function.
CERT_PUBKEY_ALG_PROP_ID	Array of BYTES	Returns the ASN.1 encoded public key algorithm parameters. This property will only be set for public keys supporting algorithm parameter inheritance and when the parameters have been omitted for the encoded and signed certificate.
CERT_PVK_FILE_PROP_ID	Array of BYTEs	Returns a NULL-terminated Unicode, wide character string specifying the file name containing the private key associated with the certificate's public key.
CERT_SHA1_HASH_PROP_ID	Array of BYTEs	Returns the SHA1 hash. If the hash does not exist, it is computed using the CryptHashCertificate function.
CERT_SIGNATURE_HASH_PROP_ID	Array of BYTEs	Returns the signature hash. If the hash does not exist, it is computed with the CryptHashToBeSigned function. The length of the hash is 20 bytes for SHA and 16 for MD5.

For all other property identifiers, the pvData parameter points to an array of bytes and not a CRYPT_DATA_BLOB structure as pointed to by the pvData parameter in the CertSetCertificateContextProperty function.

For more details about each property identifier, see the documentation on the dwPropId parameter in the CertSetCertificateContextProperty function.

pvData
[out] Pointer to a buffer to receive the data as determined by the dwPropId parameter. Structures pointed to by members of a structure returned are also returned following the base structure. Therefore, the size contained in the pcbData parameter often exceeds the size of the base structure.

This parameter can be NULL to set the size of the information for memory allocation purposes.
pcbData
[in/out] Pointer to a DWORD value specifying the size, in bytes, of the buffer pointed to by the pvData parameter. When the function returns, the DWORD value contains the number of bytes to be stored in the buffer.

Note When processing the data returned in the buffer, applications must 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 fits 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

If the function succeeds, the return value is TRUE.

If the function fails, the return value is FALSE.

For extended error information, call the GetLastError function. The following table lists some possible error codes.

Value	Description
CRYPT_E_NOT_FOUND	The certificate does not have the specified property.
ERROR_MORE_DATA	If the buffer specified by the pvData 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, in the variable pointed to by the pcbData parameter.

Note Errors from the called CryptHashCertificate function can be propagated to this function.

Requirements

Runs on	Versions	Defined in	Include	Link to
Windows CE OS	3.0 or later	Wincrypt.h		Crypt32.lib

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.

Last updated on Tuesday, July 13, 2004

CertGetCertificateContextProperty

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