CPHashSessionKey

The CPHashSessionKey function is used by applications to feed a cryptographic key to a specified hash object. This allows session keys to be hashed without the application having access to the key material.

BOOL CPHashSessionKey(
  HCRYPTPROV hProv,  // in
  HCRYPTHASH hHash,  // in
  HCRYPTKEY hKey,    // in
  DWORD dwFlags      // in
);

Parameters

hProv
Handle to a particular key container (or "context") within the CSP. This handle is obtained via a call to CPAcquireContext.
hHash
Handle to a hash object. An application obtains this handle by using the CryptCreateHash function (in the CryptoAPI).
hKey
Handle to the session key object to be hashed.
dwFlags
Flag values. No flags are currently defined.

Return Values

If the function succeeds, TRUE should be returned; otherwise, return FALSE. When FALSE is returned, the appropriate error code (see the following table) must be set via SetLastError.

Error Description
NTE_BAD_ALGID The hHash handle specifies a hash algorithm that this function does not support.
NTE_BAD_FLAGS The dwFlags parameter is non-zero.
NTE_BAD_HASH The hash object specified by the hHash parameter is invalid.
NTE_BAD_HASH_STATE An attempt was made to add data to a hash object that is already marked as "finished."
NTE_BAD_KEY A keyed hash algorithm is being used, but the session key is no longer valid. This error will be generated if the session key passed to CPCreateHash is destroyed before the hashing operating is complete.
NTE_BAD_UID The CSP context that was specified when the hash object was created cannot now be found.
NTE_FAIL The function failed in some unexpected way.

Remarks

The only data that this function is to add to the hash object is the session key material itself. If necessary, the application itself can hash in the key's salt, initialization vector, and so on. Depending on the CSP type, the key material may need to be formatted or padded in some specific way before being added to the hash. This is discussed further in Interoperability with RSA CSPs.

See Also

CPCreateHash, CPGenKey, CPHashData, CryptHashSessionKey