BCryptEnumContextFunctions function

The BCryptEnumContextFunctions function obtains the cryptographic functions for a context in the specified configuration table.

Syntax

NTSTATUS BCryptEnumContextFunctions(
  ULONG                    dwTable,
  LPCWSTR                  pszContext,
  ULONG                    dwInterface,
  ULONG                    *pcbBuffer,
  PCRYPT_CONTEXT_FUNCTIONS *ppBuffer
);

Parameters

dwTable

Identifies the configuration table from which to retrieve the context functions. This can be one of the following values.

Value Meaning
CRYPT_LOCAL
Retrieve the context functions from the local-machine configuration table.
CRYPT_DOMAIN
This value is not available for use.

pszContext

A pointer to a null-terminated Unicode string that contains the identifier of the context to enumerate the functions for.

dwInterface

Identifies the cryptographic interface to retrieve the functions for. This can be one of the following values.

Value Meaning
BCRYPT_ASYMMETRIC_ENCRYPTION_INTERFACE
Retrieve the asymmetric encryption functions.
BCRYPT_CIPHER_INTERFACE
Retrieve the cipher functions.
BCRYPT_HASH_INTERFACE
Retrieve the hash functions.
BCRYPT_RNG_INTERFACE
Retrieve the random number generator functions.
BCRYPT_SECRET_AGREEMENT_INTERFACE
Retrieve the secret agreement functions.
BCRYPT_SIGNATURE_INTERFACE
Retrieve the signature functions.
NCRYPT_KEY_STORAGE_INTERFACE
Retrieve the key storage functions.
NCRYPT_SCHANNEL_INTERFACE
Retrieve the Schannel functions.

pcbBuffer

The address of a ULONG variable that, on entry, contains the size, in bytes, of the buffer pointed to by ppBuffer. If this size is not large enough to hold the set of context identifiers, this function will fail with STATUS_BUFFER_TOO_SMALL.

After this function returns, this value contains the number of bytes that were copied to the ppBuffer buffer.

ppBuffer

The address of a pointer to a CRYPT_CONTEXT_FUNCTIONS structure that receives the set of context functions retrieved by this function. The value pointed to by the pcbBuffer parameter contains the size of this buffer.

If the value pointed to by this parameter is NULL, this function will allocate the required memory. This memory must be freed when it is no longer needed by passing this pointer to the BCryptFreeBuffer function.

If this parameter is NULL, this function will place the required size, in bytes, in the variable pointed to by the pcbBuffer parameter and return STATUS_BUFFER_TOO_SMALL.

Return Value

Returns a status code that indicates the success or failure of the function.

Possible return codes include, but are not limited to, the following.

Return code Description
STATUS_SUCCESS
The function was successful.
STATUS_BUFFER_TOO_SMALL
The ppBuffer parameter is not NULL, and the value pointed to by the pcbBuffer parameter is not large enough to hold the set of contexts.
STATUS_INVALID_PARAMETER
One or more parameters are not valid.
STATUS_NO_MEMORY
A memory allocation failure occurred.
STATUS_NOT_FOUND
No context functions that match the specified criteria were found.

Remarks

BCryptEnumContextFunctions can be called only in user mode.

Examples

The following example shows how to use the BCryptEnumContextFunctions function to enumerate the key storage functions for all contexts in the local-machine configuration table.

C++
#include <windows.h>
#include <stdio.h>
#include <Bcrypt.h>
#pragma comment(lib, "Bcrypt.lib")

#ifndef NT_SUCCESS #define NT_SUCCESS(Status) ((NTSTATUS)(Status) >= 0) #endif

NTSTATUS EnumContextFunctions() { NTSTATUS status; ULONG uSize = 0; PCRYPT_CONTEXTS pContexts = NULL;

// Get the contexts for the local machine. 
// CNG will allocate the memory for us.
status = BCryptEnumContexts(CRYPT_LOCAL, &amp;uSize, &amp;pContexts);
if(NT_SUCCESS(status))
{
    // Enumerate the context identifiers.
    for(ULONG uContextIndex = 0; 
        uContextIndex &lt; pContexts-&gt;cContexts; 
        uContextIndex++)
    {
        wprintf(L"Context functions for %s:\n", 
            pContexts-&gt;rgpszContexts[uContextIndex]);

        // Get the functions for this context.
        // CNG will allocate the memory for us.
        PCRYPT_CONTEXT_FUNCTIONS pContextFunctions = NULL;
        status = BCryptEnumContextFunctions(
            CRYPT_LOCAL, 
            pContexts-&gt;rgpszContexts[uContextIndex], 
            NCRYPT_SCHANNEL_INTERFACE, 
            &amp;uSize, 
            &amp;pContextFunctions);
        if(NT_SUCCESS(status))
        {
            // Enumerate the functions.
            for(ULONG i = 0; 
                i &lt; pContextFunctions-&gt;cFunctions; 
                i++)
            {
                wprintf(L"\t%s\n", 
                    pContextFunctions-&gt;rgpszFunctions[i]);
            }

            // Free the context functions buffer.
            BCryptFreeBuffer(pContextFunctions);
        }
    }

    // Free the contexts buffer.
    BCryptFreeBuffer(pContexts);
}

return status;

}

Requirements

   
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Target Platform Windows
Header bcrypt.h
Library Bcrypt.lib
DLL Bcrypt.dll

See Also

CRYPT_CONTEXT_FUNCTIONS