CryptHashSessionKey function

The CryptHashSessionKey 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 CryptHashSessionKey can be interspersed with calls to CryptHashData.

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

Syntax

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

Parameters

hHash [in]

A handle to the hash object.

hKey [in]

A handle to the key object to be hashed.

dwFlags [in]

The following flag value is defined.

Value	Meaning
CRYPT_LITTLE_ENDIAN 0x00000001	When this flag is set, the bytes of the key are hashed in little-endian form. Note that by default (when dwFlags is zero), the bytes of the key are hashed in big-endian form.

 

Return value

If the function succeeds, the return value is TRUE.

If the function fails, the return value is FALSE. For extended error information, call GetLastError.

The error codes prefaced by "NTE" are generated by the particular CSP you are using. Some possible error codes follow.

Examples

The following example shows computing the cryptographic hash of a session key object.

//--------------------------------------------------------------------
//  This code assumes that a cryptographic context handle has been 
//  acquired, that a hash object handle (hHash) has been
//  created, and that a session key handle (hKey) has been 
//  created.
//--------------------------------------------------------------------
// Compute the cryptographic hash on the key object.

if(CryptHashSessionKey(
   hHash, 
   hKey, 
   0))
{
    printf("The session key has been hashed. \n");
}
else
{
    printf("Error during CryptHashSessionKey!\n");
    exit(1);
}

// 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 the message originator 
// if the session key used is also exported to them.

//--------------------------------------------------------------------
// Clean up. Destroy the hash object and the session key.

if(hHash) 
   CryptDestroyHash(hHash);
if(hKey) 
   CryptDestroyKey(hKey);

For an example that includes the complete context for this example, see Example C Program: Creating and Hashing a Session Key.

Requirements

See also

Hash and Digital Signature Functions

CryptCreateHash

CryptGenKey

CryptHashData