CryptHashSessionKey

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This function computes the cryptographic hash of a session key object. This function can be called multiple times with the same hash handle to compute the hash of multiple keys. Calls to the CryptHashSessionKey function can be interspersed with calls to the CryptHashData function.

Before calling this function, the CryptCreateHash function must be called to get a handle to a hash object.

Syntax

BOOL WINAPI CryptHashSessionKey( 
  HCRYPTHASH hHash,
  HCRYPTKEY hKey, 
  DWORD dwFlags
);

Parameters

• hHash
  [in] HCRYPTHASH handle to the hash object created by calling the CryptCreateHash function.

• hKey
  [in] HCRYPTKEY handle to the key object to be hashed.

• dwFlags
  [in] Reserved for future use and must be set to zero.

Return Value

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

The following table shows the common values for the GetLastError function. The error values prefaced by NTE are generated by the particular cryptographic service provider (CSP) you are using.

Example Code

#include <wincrypt.h>
HCRYPTPROV hProv = 0;
HCRYPTHASH hHash = 0;
HCRYPTKEY hKey = 0;
// Get a handle to the default provider using CryptAcquireContext.
// For sample code, see <A HREF="wce50lrfcryptacquirecontext.htm">CryptAcquireContext</A>.
...
...
// Create a hash object.
if(!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash)) {
 printf("Error %x during CryptBeginHash!\n", GetLastError());
 goto done;
}
// Create a random session key.
if(!CryptGenKey(hProv, CALG_RC2, CRYPT_EXPORTABLE, &hKey)) {
 printf("Error %x during CryptGenKey!\n", GetLastError());
 goto done;
}
// Compute the cryptographic hash on the key object.
if(!CryptHashSessionKey(hHash, hKey, 0)) {
 printf("Error %x during CryptHashSessionKey!\n", GetLastError());
 goto done;
}
// Use the hash of the key object. For instance, additional 
// data could be hashed and sent in a message to several recipients. 
// The recipients will be able to verify who the message originator 
// is if the key used is also exported to them..
...
done:
// Destroy the hash object.
if(hHash) CryptDestroyHash(hHash);
// Destroy the session key.
if(hKey) CryptDestroyKey(hKey);
// Free the CSP handle.
if(hProv) CryptReleaseContext(hProv,0);
 

Requirements

See Also

Reference

CryptCreateHash
CryptGenKey
CryptHashData