Function C_Decrypt 

pub unsafe extern "C" fn C_Decrypt(
    hSession: CK_SESSION_HANDLE,
    pEncryptedData: CK_BYTE_PTR,
    ulEncryptedDataLen: CK_ULONG,
    pData: CK_BYTE_PTR,
    pulDataLen: CK_ULONG_PTR,
) -> CK_RV