Using Cryptor DLL Functions

If you use Cryptor from XiTech for encryption in VFP, you may be aware that its FLL is sensitive to the version of VFP you're using. For example, C40Fox80.FLL is for VFP 8, C40Fox70.FLL is for VFP 7, etc. Although Cryptor 5 has been available for some time, I haven't bothered to upgrade because version 4 does everything I need it to. Also, there are some installation issues with Cryptor 5 on Vista, since it's now a COM object, while version 4 doesn't need registration. One problem with version 4, though, is that it doesn't come with an FLL for VFP 9.

Fortunately, you don't need one. Cryptor comes with a DLL, XICrCore.DLL, that contains functions providing Cryptor features. I use a class called SFCryptor that's a wrapper for the DLL. You can download it from the Technical Papers page of my Web site.

Here are the declarations for these functions:

lcDLL = fullpath('XICrCore.dll', addbs(.cCryptorPath))
declare integer CRYIni_Initialize      in (lcDLL) ;
    integer LoadMode
declare integer CRYIni_InitializeEx    in (lcDLL) ;
    integer dwLoadMode, integer hModule, string strExclusionList
declare integer CRYIni_UnInitialize    in (lcDLL)
declare integer CRYUtl_EncodeString    in (lcDLL) ;
    string strSrc, string @ strDest, integer dwLength, ;
    string strPassword, integer dwMethod
declare integer CRYUtl_DecodeString    in (lcDLL) ;
    string strSrc, string @ strDest, integer dwLength, ;
    string strPassword, integer dwMethod
declare string  CRYUtl_GetErrorMessage in (lcDLL) ;
    integer errorCode
declare integer CRYUtl_Encode          in (lcDLL) ;
    string strFilename, string strPassword, string strBackupExt, ;
    integer bKeepBackup, integer dwMethod
declare integer CRYUtl_Decode          in (lcDLL) ;
    string strFilename, string strPassword, string strBackupExt, ;
    integer bKeepBackup, integer dwMethod
declare integer CRYMan_Register        in (lcDLL) ;
    string strFilename, string strPassword, integer dwFlags, ;
    integer dwMethod
declare integer CRYMan_Unregister      in (lcDLL) ;
    string strFilename
declare integer CRYMan_List            in (lcDLL) ;
    integer dwFunction, string @ strFilename, integer @ pdwFlags, ;
    integer @ pdwMethod, integer @ pdwCount

This code initializes Cryptor:

#define CRYPTOR_ERR_SUCCESS             0x00000000
#define CRYPTOR_ERR_ALREADY_INITIALIZED 0xFFFFFF02 - 0x100000000
if version(2) = 0
    declare integer GetModuleHandle in Win32API string ModuleName
    lnHookModule = GetModuleHandle('VFP' + ;
        left(transform(version(5)), 1) + 'R.DLL')
    if lnHookModule <> 0 
        lnStatus = CRYIni_InitializeEx(2, lnHookModule, ';')
    else    
        lnStatus = -1
    endif lnHookModule <> 0
else
    lnStatus = CRYIni_InitializeEx(2, 0, ';')
endif version(2) = 0
if inlist(lnStatus, CRYPTOR_ERR_SUCCESS, ;
    CRYPTOR_ERR_ALREADY_INITIALIZED)
    llInitialized = .T.
else
    lcErrorMessage = 'Could not initialize Cryptor: status ' + ;
        'code ' + transform(lnStatus)
    llInitialized = .F.
endif inlist(lnStatus ... 

This code registers, unregisters, encrypts, or decrypts a file; pass it the filename, password, encryption method, and "register" to register the file, "unregister" to unregister it, "encrypt" to encrypt it, or "decrypt" to decrypt it. Error handling code was removed for brevity.

lparameters tcFileName, ;
    tcPassword, ;
    tnMethod, ;
    tcProcess
local laFiles[1], ;
    lnFiles, ;
    lcPath, ;
    lnI, ;
    lcFile, ;
    lnStatus, ;
    llReturn

* Get the file to process. Use ADIR() because we may a file skeleton
* like SOMETHING.*.

lnFiles = adir(laFiles, tcFileName)

* Try to process the file(s).

lcPath = addbs(justpath(tcFileName))
for lnI = 1 to lnFiles
    lcFile = lower(lcPath + laFiles[lnI, 1])
    do case
        case tcProcess = 'encrypt'
         lnStatus = CRYUtl_Encode(lcFile, tcPassword, .NULL., 0, ;
             tnMethod)
      case tcProcess = 'decrypt'
         lnStatus = CRYUtl_Decode(lcFile, tcPassword, .NULL., 0, ;
              tnMethod)
      case tcProcess = 'register'
          lnStatus = CRYMan_Register(lcFile, tcPassword, 0, tnMethod)
      case tcProcess = 'unregister'
          lnStatus = CRYMan_Unregister(lcFile)
    endcase
    llReturn = lnStatus = CRYPTOR_ERR_SUCCESS
    if not llReturn
        lcErrorMessage = 'Could not ' + tcProcess + ' ' + lcFile + ;
            ': ' + CRYUtl_GetErrorMessage(lnStatus)
       exit
  endif not llReturn
next lnI
return llReturn