CryptINI

CryptINI

PURPOSE

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This is a TiniFile implementation that is resistant to tampering. In normal (PlainTextMode = FALSE) mode, any calls to Write values are accompanied by an embedded MD5 hash value (and also reversed then Base64/IDEA Encrypted) This is invisible in normal use (i.e. read methods return normal results) but there are added methods to internally verify any entries. It also is able to write a standard ident section containing various details including authorship and copyright. A single function allows you to check on app startup whether this section has been altered. It also includes a useful 'First Run' functionality. It's intended purpose is to store information that cannot be easily altered in a text editor (such as HiScores etc) by a weekend scripter. The WriteInteger method is the most secure as it double-encrypts as well as embedding an MD5Hash value as a checksum. Very handy to save scores etc. It is paired with ReadInteger and VerifyInteger

DISCLAIMER

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This unit does not claim to pass any security tests nor be used in any environment where a moderate-level hacker could circumvent it.

ENCRYPTION

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By Default CryptINI uses the DCPCrypt package for string encryption. The mode is IDEA cipher with an MD5 hash for the key. The EncryptINI and DecryptINI methods use DCPCrypt RC4 Cipher (With SHA hash) There is a $DEFINE USE_DCPCRYPT directive at the top of this file.

If this DEFINE is commented out, then CryptINI will default to BASE64 string encryption, which is weaker. Encrypt/DecryptINI methods will be unavailable. You can then delete any requirement for dcpcrypt in the project inspector.

FREEPASCAL VERSIONS

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Starting in FPC V3.0 there are additional options in TINIFile which are implemented in TCryptINI if the FPC Version >= 3 is detected.

USE AND EXAMPLE CODE

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• • You can hard-code an Ident Section in your INI file
  • and check if it has been altered
  • Typical Form.Create()

procedure TForm1.FormCreate(Sender: TObject); const

 C_KEYPHRASE = 'I do like to be beside the seaside'; // Move this to the top of the unit

Begin

...other code
// Initialise the encrypted config file
INI := TCryptIniFile.Create(ChangeFileExt(Application.EXEName, '.cfg'));

// First ever run.  INI is absent
If INI.IsVirgin then INI.WriteIdent('minesadorada','(c)2016','minesadorada@charcodelvalle.com','Creative Commons',TRUE);l

if NOT INI.VerifyIdent('5b319674f5cb55f3ed1e404e33c25868') then // I got this from the INI file
  ShowMessage('This is not a genuine copy of ' + Application.Title + '!')
else INI.Deflower; // If not Deflowered then the default ini is used.

// After first run, use the encrypted version
If NOT INI.IsVirgin then
begin
  INI.DecryptINI(TRUE,C_KEYPHRASE);
// Check the unencrypted version..
  if NOT INI.VerifyIdent('5b319674f5cb55f3ed1e404e33c25868') then // I got this from the INI file
  ShowMessage('This is not a genuine copy of ' + Application.Title + '!');
end;
INI.KeyPhrase:=C_KEYPHRASE; // for subsequent read/writes
...other code

end;

procedure Tmainform.FormDestroy(Sender: TObject); const

 C_KEYPHRASE = 'I do like to be beside the seaside'; // Move this to the top of the unit

Begin

...other code
 INI.EncryptINI(TRUE,C_KEYPHRASE);
 ...other code

end;

• • Has the Ident been tampered with? Put this in Form.Create

// Use the MD5 value from the INI file (use your own!) If INI.VerifyIdent('92abf0deecbb25c435bff507a396d92a') then

 ShowMessage('Ident verified OK') // do nothing

else

 ShowMessage('Ident failed verification'); // Warning message/exit

• • Test for first run

If INI.IsVirgin then // note that doing the test Deflowers the app by default

  ShowMessage('First time run of this app');

• • Toggle to normal UnEncrypted INI use

(by default it is set to FALSE) INI.PlainTextMode:=TRUE; INI.WriteString('MySection', 'String', 'MyString'); // just writes normally

• • When PlainTextMode = FALSE (default),Write<anytype> encrypts the value

  and prefixes the encrypted value with an MD5Hash

INI.WriteInteger('MySection', 'Integer',1000);

• • Note WriteInteger adds a '+' (INTEGER_MARKER) to the written Key

  This is so that CryptINI can deal with Integers specially
  Using CryptINI in either mode, this is invisible in use
  (i.e. don't add a + to the ident for any methods)

• • When PlainTextMode = FALSE (default), use these convenient methods if you like:

INI.ReadUnencryptedString INI.WriteUnencryptedString INI.ReadUnEncryptedInteger INI.WriteUnencryptedInteger

• • Store 'First Run' status using these methods:

INI.IsVirgin INI.Deflower INI.ReFlower (useful for testing)

• • You can encrypt and decrypt the entire INI file usine EncryptINI and DecryptINI

  This uses a different cipher and hash method, so is extra-secure
  cryptINI methods and properties an only work with an unencrypted INI file
  So; Decrypt on startup, and Encrypt before exit.
  By default the routines use the KeyPhrase property, but you can override this
  in the method call along with whether to delete the "old" file and what
  file extension to use for the encrypted file.

• • Original IniFiles methods and properties

  Just use them as normal. Note: you can mix-and-match Plaintext and Encrypted
  in the same INI file. Just toggle the property PlainTextMode before Writing/Reading