BCryptQueryContextFunctionConfiguration function (bcrypt.h)

[BCryptQueryContextFunctionConfiguration is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions.]

The BCryptQueryContextFunctionConfiguration function obtains the cryptographic function configuration information for an existing CNG context.

Syntax

NTSTATUS BCryptQueryContextFunctionConfiguration(
  [in]      ULONG                          dwTable,
  [in]      LPCWSTR                        pszContext,
  [in]      ULONG                          dwInterface,
  [in]      LPCWSTR                        pszFunction,
  [in, out] ULONG                          *pcbBuffer,
  [in, out] PCRYPT_CONTEXT_FUNCTION_CONFIG *ppBuffer
);

Parameters

[in] dwTable

Identifies the configuration table that the context exists in. This can be one of the following values.

[in] pszContext

A pointer to a null-terminated Unicode string that contains the identifier of the context to obtain the function configuration information for.

[in] dwInterface

Identifies the cryptographic interface to obtain the function configuration information for. This can be one of the following values.

[in] pszFunction

A pointer to a null-terminated Unicode string that contains the identifier of the cryptographic function to obtain the configuration information for.

[in, out] 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 context information, this function will fail with STATUS_BUFFER_TOO_SMALL.

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

[in, out] ppBuffer

The address of a pointer to a CRYPT_CONTEXT_FUNCTION_CONFIG structure that receives the function configuration information 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.

For more information about the usage of this parameter, see Remarks.

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.

Remarks

Each cryptographic function has only one set of configuration information, so although the ppBuffer parameter appears to be a used as an array, this function treats this as an array with only one element. The following example helps clarify how this parameter is used.

// Get the function configuration information.
CRYPT_CONTEXT_FUNCTION_CONFIG FuncConfig;
ULONG uSize = sizeof(FuncConfig);
PCRYPT_CONTEXT_FUNCTION_CONFIG pFuncConfig = &FuncConfig;
status = BCryptQueryContextFunctionConfiguration(
    CRYPT_LOCAL, 
    pszContext, 
    NCRYPT_SCHANNEL_INTERFACE,
    pszFunction,
    &uSize, 
    &pFuncConfig);

BCryptQueryContextFunctionConfiguration can be called only in user mode.

Requirements

See also

CRYPT_CONTEXT_FUNCTION_CONFIG