DCPCrypt Transportability

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FOV_2001:
Dear All,

After a lot of test, I have a problem with DCPCrypt Library from one machine encrypting in Delphi, to be decrypted in other machine using Lazarus

Same Library (DCPCrypt) same Hash and Same Cypher.

Here the Encrypt and Decrypt functions SAME at both programs (Delphi & Lazarus)

--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---function TMod_Encripcion.Encrypt_String(KeyStr, Texto : String): string; var i: integer; Cipher: TDCP_3des; begin if KeyStr <> '' then // get the passphrase begin Cipher:= TDCP_3des.Create(Self); Cipher.InitStr(KeyStr,TDCP_sha256); // initialize the cipher with a hash of the passphrase Result := Cipher.EncryptString(Texto); Cipher.Burn; Cipher.Free; end; end; function TMod_Encripcion.Decrypt_String(KeyStr, Texto : String): string; var i: integer; Cipher: TDCP_3des; begin if KeyStr <> '' then // get the passphrase begin Cipher:= TDCP_3des.Create(Self); Cipher.InitStr(KeyStr,TDCP_sha256); // initialize the cipher with a hash of the passphrase Result := Cipher.DecryptString(Texto); Cipher.Burn; Cipher.Free; end; end;
The result on the same machine Works perfectly, BUT if I take the Encrypted result on one machine, and try to decrypt on the other, the result is literally garbage.

Any thougths, & or help to makle this transportable, Will be appreciated.

Xor-el:
Direct encryption on strings is always bound to end in tears because of encoding and OS format settings differences.
Also do note that Modern Delphi strings are UTF16 while Lazarus/FPC is ANSI, UTF8 or UTF16 depending on the mode.

All these been said, I suggest you operate on bytes directly to avoid issues like this.

Thaddy:
Indeed, especially for Ansi vs UTF8 .
IBut when both sides use the Unicodestring versions (That is UTF16) it should work on every machine.

That said, better to use the EncryptDecrypt versions on the data as bytes, or the streams.
Make sure that the string types are properly and specifically declared. If you use unicodestring as string type it is likely to work,

FOV_2001:

--- Quote from: Thaddy on February 10, 2020, 07:05:29 pm ---Indeed, especially for Ansi vs UTF8 .
IBut when both sides use the Unicodestring versions (That is UTF16) it should work on every machine.

That said, better to use the EncryptDecrypt versions on the data as bytes, or the streams.
Make sure that the string types are properly and specifically declared. If you use unicodestring as string type it is likely to work,

--- End quote ---

Yes, I'm trying to find the differences and where they are, in order to get a solution.

Thanks a lot to both of you for the comments.

till now, UTF-8 vs UTF-16 seems to bee relevant, the length of the keys and paddings, may be other ones.

Keep you posted.

ezlage:
Maybe the problem is at storing an encrypted output at a string variable type. I always transport the ciphertext in base64, base85 or hexadecimal. This way we avoid unexpected treatment from different scenarios.

I mean, I get the output bytes - not the string - and encode them to a hex/base64/base85 string.

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