how do I export a certificate to x.509?

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A

Anyone

From Visual C++ how can I export a certificate to x.509? I need to pass
this to a third party crypt library we're migrating away from. There are
many Cert?????? functions but no CertExport().


Thanks in advance
 
I'm clear about your question. Do you already have a certifiate? Or do you
want to export a certificate from an existing store on Windows machine?

If you want to export a certificate from an existing store, you need to open
the store (use CertOpenStore API) and then find the certificate you want to
export (CertFindCerticateInStore API) and then you can just store the
pbCertEncoded field on CERT_CONTEXT structure in a file.

Thanks,
Vishal [MSFT]
 
Just this morning I realized CERT_CONTEXT contained the x.509 certificate in
the pbCertEncoded member.

Thanks.


Vishal Agarwal said:
I'm clear about your question. Do you already have a certifiate? Or do you
want to export a certificate from an existing store on Windows machine?

If you want to export a certificate from an existing store, you need to open
the store (use CertOpenStore API) and then find the certificate you want to
export (CertFindCerticateInStore API) and then you can just store the
pbCertEncoded field on CERT_CONTEXT structure in a file.

Thanks,
Vishal [MSFT]

--
This posting is provided "AS IS" with no warranties, and confers no rights
Anyone said:
From Visual C++ how can I export a certificate to x.509? I need to pass
this to a third party crypt library we're migrating away from. There are
many Cert?????? functions but no CertExport().


Thanks in advance
Click to expand...
Click to expand...
 
// sorry about the formatting but you can enumerate certificates (PFX and Public Keys like below.

*iNumCerts = 0;
HCERTSTORE hTempStore = 0;
HCERTSTORE hLocalStore = NULL;
HCRYPTPROV *phProv = 0;
PCCERT_CONTEXT pContext = 0;
HCRYPTPROV hCryptProv = 0;
DWORD dwReturnCode = 0;
__try




{
__try






{
DWORD dwCertStore = CERT_SYSTEM_STORE_CURRENT_USER;




​
if(!(hLocalStore = CertOpenStore(
CERT_STORE_PROV_SYSTEM,


0,
NULL,
dwCertStore,

L"MY")))
{
dwReturnCode = GetLastError();

_tprintf(_T("Failed to open store %s (%d)\n"), lpszStoreName, dwReturnCode);

__leave;

}

while ( (pContext = CertEnumCertificatesInStore(hLocalStore,

pContext)) )

{



BOOL bPfxFile = FALSE;


DWORD dwKeySpec = AT_SIGNATURE;
BOOL bFreeCertKey = TRUE;
// if its a PFX file we get a private key, if standard public CERT not private key available.




bPfxFile = CryptAcquireCertificatePrivateKey(pContext,
0,


NULL,
&hCryptProv,
&dwKeySpec,
&bFreeCertKey);


​
// got private key for this item. Open certificate







​
if ( !( hTempStore = CertOpenStore(
CERT_STORE_PROV_MEMORY,


hCryptProv,
NULL,
(bPfxFile?CERT_STORE_OPEN_EXISTING_FLAG:0), 0)) )


​
{





​
if ( bPfxFile )



{
// failed to open certificate store so leave.
CryptReleaseContext(hCryptProv, 0);

hCryptProv = 0;

}

DWORD dwErr = GetLastError();

_tprintf(_T("Warning CertOpenStore failed (%d)\n"), dwErr);

continue;

}

// get friendly name



TCHAR lpszFriendlyName[MAX_PATH] = {'\0'};

DWORD dwSize = sizeof(lpszFriendlyName) * sizeof(TCHAR);

LPSTR dwStrType = szOID_COMMON_NAME;



CertGetNameString(pContext,
CERT_NAME_SIMPLE_DISPLAY_TYPE,
CERT_NAME_STR_ENABLE_PUNYCODE_FLAG,
&dwStrType,
lpszFriendlyName,

dwSize);

CRYPT_DATA_BLOB pPFX = {'\0'};
// add the certificate to our memory store
CertAddCertificateContextToStore(hTempStore,

pContext,

CERT_STORE_ADD_USE_EXISTING,

NULL);
// if its a PFX key we want the private keys
DWORD dwExportFlags = EXPORT_PRIVATE_KEYS|PKCS12_INCLUDE_EXTENDED_PROPERTIES;

if ( bPfxFile )



{
// export the keys to a blob to write out to file
if ( !PFXExportCertStoreEx(hTempStore,

&pPFX,

lpszPassCode,

NULL,

dwExportFlags) )

{

CertCloseStore(hTempStore, 0);

if ( bPfxFile )
{
CryptReleaseContext(hCryptProv, 0);
hCryptProv = 0;
}
hTempStore = 0;
continue;

}
pPFX.pbData = (BYTE *)CryptMemAlloc(pPFX.cbData * sizeof(BYTE));

PFXExportCertStoreEx(hTempStore,
&pPFX,
lpszPassCode,
NULL,
dwExportFlags);
// the pPFX blob now has our binary certificate and size so simply write out to an external file
}

else

{
// this is not a PFX so we can simply write the blob directly.
// pContext->cbCertEncoded;
// pPFX.pbData = pContext->pbCertEncoded;
}

if ( bPfxFile )

CryptMemFree(pPFX.pbData);

CertCloseStore(hTempStore, 0);

if ( bPfxFile )

{

CryptReleaseContext(hCryptProv, 0);

hCryptProv = 0;

}

hTempStore = 0;

}



​
}



__finally

{

if ( hLocalStore )

CertCloseStore(hLocalStore,0);

return dwReturnCode;

}



​
}



__except(0)

{

dwReturnCode = GetExceptionCode();

return dwReturnCode;

}

 
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