[This is preliminary documentation and subject to change.]
The CryptFormatObject function formats the encoded data and returns a Unicode string in the allocated buffer according to the certificate encoding type.
#include <wincrypt.h>
BOOL WINAPI CryptFormatObject(
DWORD dwCertEncodingType, // in
DWORD dwFormatType, // in
DWORD dwFormatStrType, // in
void *pFormatStruct, // in
LPCSTR lpszStructType, // in
const BYTE *pbEncoded, // in
DWORD cbEncoded, // in
void *pbFormat, // out
DWORD *pcbFormat // in/out
);
| Encoding type | Value |
|---|---|
| X509_ASN_ENCODING | 0x00000001 |
Currently defined values are shown in the following table:
| Format value | Description |
|---|---|
| 0 | Display the data in single line. Each subfield is concatenated with a ", " (see Remarks). |
| CRYPT_FORMAT_ STR_MULTI_LINE |
Display the data in multiple lines rather than the default of a single line display (see Remarks). |
| CRYPT_FORMAT_ STR_NO_HEX |
Disables the hex dump (see Remarks). |
The following table is a listing of supported OIDs with the associated OID extension:
| OID Name | OID |
|---|---|
| SPC_FINANCIAL_CRITERIA_OBJID | 1.3.6.1.4.1.311.2.1.27 |
| SPC_SP_AGENCY_INFO_OBJID | 1.3.6.1.4.1.311.2.1.10 |
| szOID_AUTHORITY_INFO_ACCESS | 1.3.6.1.5.5.7.1.1 |
| szOID_AUTHORITY_KEY_IDENTIFIER2 | 2.5.29.35 |
| szOID_BASIC_CONSTRAINTS2 | 2.5.29.19 |
| szOID_CERT_POLICIES | 2.5.29.32 |
| szOID_CRL_DIST_POINTS | 2.5.29.31 |
| szOID_CRL_REASON_CODE | 2.5.29.21 |
| szOID_ENHANCED_KEY_USAGE | 2.5.29.37 |
| szOID_ISSUER_ALT_NAME2 | 2.5.29.18 |
| szOID_KEY_ATTRIBUTES | 2.5.29.2 |
| szOID_KEY_USAGE | 2.5.29.15 |
| szOID_KEY_USAGE_RESTRICTION | 2.5.29.4 |
| szOID_NEXT_UPDATE_LOCATION | 1.3.6.1.4.1.311.10.2 |
| szOID_RSA_SMIMECapabilities | 1.2.840.113549.1.9.15 |
| szOID_SUBJECT_ALT_NAME2 | 2.5.29.17 |
| szOID_SUBJECT_KEY_IDENTIFIER | 2.5.29.14 |
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.
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.
If the function succeeds, the return value is TRUE. If it does not succeed, the return value is FALSE. To retrieve extended error information, use the GetLastError function.
The default behavior of CryptFormatObject is to return single line display of the encoded data, that is, each subfield will be concatenated with a ", " on one line. If a user prefers to display the data in multiple line, set the flag CRYPT_FORMAT_STR_MULTI_LINE, that is, each subfield will be displayed on a separate line.
If there is no formatting routine installed or registered for the lpszStructType, the hex dump of the encoded BLOB Structure will be returned. A user can set the flag CRYPT_FORMAT_STR_NO_HEX to disable the hex dump.
// EXAMPLE CODE FOR USING CryptFormatObject().
// Assume that a pointer to an encoded data structure
// (pbEncoded) is already known.
// Set up the variables.
DWORD dwCertEncodingType; // Type of encoding
DWORD dwFormatType; // Format type
DWORD dwFormatStrType; // Structure format flags
LPCSTR pFormatStruct; // Pointer to structure format- set to NULL
LPCSTR lpszStructType; // Pointer to type of encoding
const BYTE *pbEncoded; // Pointer to the encoded object to be read
// and formatted
DWORD cbEncoded; // size of structure
BYTE *pbFormat; // Pointer to the formatted string
DWORD pcbFormat;
DWORD cbFormat; // size of the formated object
BOOL fResult; // Return value- True if function successful
// False if function fails
// initalize the pointers/ structure
cout<< "Begin initalization."<< endl;
fResult= CryptFormatObject(
X509_ASN_ENCODING, // in- dwCertEncodingType
0, // in- dwFormatType set to 0
CRYPT_FORMAT_STR_MULTI_LINE,// in- dwFormatStrType- print
// in multiple line format
NULL, // in- FormatStruct set to NULL
szOID_CERT_POLICIES, // in- Structure name
pbEncoded, // in- Pointer to data
// structure to be formatted
// initialized elsewhere
1024, // in- size in bytes
NULL, // out- set to NULL to allocate
// memory
&cbFormat); // in/out- pbFormat size
if (!fResult){
cout<< "First call to CryptFormatObject failed"<< endl;
}
else {
cout<< "First call to CryptFormatObject successful"<< endl;
pbFormat = (BYTE*)malloc (cbFormat);
cout<< "memory allocated" << endl;
// Function call to format the object
fResult= CryptFormatObject(
X509_ASN_ENCODING, // in- dwCertEncodingType
0, // in- dwFormatType set to 0
CRYPT_FORMAT_STR_MULTI_LINE,// in- dwFormatStrType- print
// in multiple line format
NULL, // in- FormatStruct set to NULL
szOID_CERT_POLICIES, // in- Structure name
pbEncoded, // in- initialized elsewhere
1024, // in- size in bytes
pbFormat, // out- pbFormat
&cbFormat); // in/out- pbFormat size
if (!fResult){
cout<< "Second call to CryptFormatObject failed"<< endl;
}
else {
cout<< "Second call to CryptFormatObject successful"<< endl
<< "The string is "<< pbFormat<< endl
<< "size of pbFormat (cbFormat)= "<< cbFormat<< endl;
}
free(pbFormat);
}
}
Windows NT: Requires version 5.0 or later.
Windows: Unsupported.
Windows CE: Unsupported.
Header: Declared in wincrypt.h.
Import Library: Use crypt32.lib.