CryptMsgDuplicate

[This is preliminary documentation and subject to change.]

The CryptMsgDuplicate function duplicates a cryptographic message handle by incrementing the reference count. The reference count keeps track of the lifetime of the message.

#include <wincrypt.h>
HCRYPTMSG WINAPI CryptMsgDuplicate(
  HCRYPTMSG hCryptMsg            // in
);

Parameters

hCryptMsg: Handle to the cryptographic message for which the reference count is being incremented.

Return Values

A copy is not made of the message, and the returned handle is the same as the handle that was input.

Remarks

CryptMsgDuplicate is used to increase the reference count on a HCRYPTMSG handle so that multiple calls to CryptMsgClose are required to actually release the handle.

Example

// EXAMPLE CODE FOR USING CryptMsgDuplicate().
// Duplicates a message handle by incrementing its reference count.

// Assume that the application has a handle (hCryptMsg) 
// to the message that is to be duplicated.

// Set up the variables.
HCRYPTMSG hCryptMsg;         // Message handle
HCRYPTMSG hResult;           // Duplicated message handle

// Function call to CryptMsgDuplicate to duplicate the handle.
hResult = CryptMsgDuplicate(
            hCryptMsg);      // in- Initialized elsewhere

if (hResult){                // returned value is the handle
  cout<< "CryptMsgDuplicate is successful"<< endl
      << "original handle (hCryptMsg) = "<< hCryptMsg<< endl
      << "Duplicate handle (hResult) = "<< hResult<< endl
      << "Note that they are identical"<< endl
      << "The handle reference count has been incremented"<< endl
      << endl;

  // Free memory. Multiple calls to CryptMsgClose are required to
  // decrement the reference count and actually release the handle.
  CryptMsgClose(hResult);
  CryptMsgClose(hCryptMsg);
  }
else{                        // returned value is NULL
  cout<< "CryptMsgDuplicate is not successful"<< endl<< endl;
  }

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