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4/8/2010

This function specifies the default cryptographic service provider (CSP) for the current user or the local device.

If a current user's default provider is set, that default provider is acquired by any call by that user to the CryptAcquireContextfunction specifying a dwProvTypeprovider type but not a CSP name.

If a local computer default is set, calls to the CryptAcquireContextfunction by a user not having a current user default set and not specifying a CSP result in the use of the local computer's default CSP.

Typical applications do not use this function. It is intended for use solely by administrative applications.

Syntax 

BOOL WINAPI CryptSetProviderEx( 
  LPCTSTR 
pszProvName, 
  DWORD 
dwProvType, 
  DWORD* 
pdwReserved, 
  DWORD 
dwFlags
);

Parameters

pszProvName

[in] Pointer to the null-terminated string that contains the name of the new default CSP. This must be a CSP installed on the computer.

dwProvType

[in] Specifies the provider type of the CSP specified by the pszProvNameparameter.

pdwReserved

[in] Reserved for future use and must be set to NULL.

dwFlags

[in] Bitmask of flags. The following table shows defined values for this parameter.

Value Description

CRYPT_MACHINE_DEFAULT

Sets the machine default CSP of the given type.

CRYPT_USER_DEFAULT

Sets the user default CSP of the given type.

CRYPT_DELETE_DEFAULT

Can be used in conjunction with CRYPT_MACHINE_DEFAULT or CRYPT_USER_DEFAULT to delete the default.

Return Value

TRUE indicates success. FALSE indicates failure. To get extended error information, call the GetLastErrorfunction.

The following table shows the common values for the GetLastErrorfunction. The error values prefaced by NTE are generated by the particular CSP you are using.

Value Description

ERROR_INVALID_PARAMETER

One of the parameters contains an invalid value. This is most often an illegal pointer.

ERROR_NOT_ENOUGH_MEMORY

The operating system ran out of memory.

Remarks

Most applications do not specify a CSP name when calling the CryptAcquireContextfunction; however, an application has the option of selecting a specific CSP. This gives the user the freedom to select a CSP with an appropriate level of security.

Because calling CryptSetProviderExdetermines the CSP of a specified type used by all applications that run from that point on, this function must not be called without the consent of the user.

Windows Embedded CE does not support the ANSI version of this function.

Example Code

Copy Code 
HCRYPTPROV hProv = 0;
// Specify the default PROV_RSA_SIG provider for the machine. Note
that this assumes that a
// CSP with a type of PROV_RSA_SIG and named "Joe's Provider" has
already been installed.
if (!CryptSetProviderEx(TEXT("Joe's Provider"), PROV_RSA_SIG, NULL,
 CRYPT_MACHINE_DEFAULT)) 
 {printf("Error %x during CryptSetProviderEx!\n", GetLastError);
 return;
 }
// Get a handle to the provider you just made default using
CryptAcquireContext
// For sample code, see <A
HREF="wce50lrfcryptacquirecontext.htm">CryptAcquireContext</A>.
...
...
// Free the provider handle.
if (!CryptReleaseContext(hProv, 0)) 
 {printf("Error %x during CryptReleaseContext!\n", GetLastError);
 return;
 }

Requirements

Header wincrypt.h
Library coredll.lib
Windows Embedded CE Windows CE 2.10 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also