CODEWITHSUNDEEP
delphiencryptionrijndael
Peacelyk
Peacelyk

Reputation: 1146

Rijndael encryption

i'm using DCPcrypt library found here.

Here is a little code to encrypt a string

InitializationVector: AnsiString;
const Key: Ansistring = 'keykeykeykey';
// Encrypt a string and return the Base64 encoded result
function Encrypt(DataToEncrypt: ansistring):ansistring;
var
  Cipher : TDCP_rijndael;
  Data: string;
  IV: array[0..15] of byte;      // the initialization vector
  i:Integer;
begin
  // Pad Key, IV and Data with zeros as appropriate
  FillChar(IV,Sizeof(IV),0);            // make the IV all zeros

  Data := PadWithZeros(DataToEncrypt,BlockSize);

  for i := 0 to (Length(IV) - 1) do   //just random values for the IV
    IV[i] := Random(256);

  Cipher := TDCP_rijndael.Create(nil);

  if Length(Key) <= 16 then
    Cipher.Init(Key[1],128,@IV[1])
  else if Length(Key) <= 24 then
    Cipher.Init(Key[1],192,@IV[1])
  else
    Cipher.Init(Key[1],256,@IV[1]);
  // Encrypt the data
  Cipher.EncryptCBC(Data[1],Data[1],Length(Data));
  // Free the cipher and clear sensitive information
  Cipher.Free;

  SetString(InitializationVector,PAnsiChar(@IV[1]),Length(IV));
  InitializationVector := Base64EncodeStr(InitializationVector);

  //Base64 encoded result
  Result := Base64EncodeStr(Data);
end;

I can decrypt the resulted string, but only half of it. Found one similar post, but he found answer when encoding cryptogram with base64 which i'm doing. Here.

Any help is appreciated!

Upvotes: 2

Views: 5006

Answers (1)

Johan
Johan

Reputation: 76537

Strings in Delphi 2009/2010 and XE are Unicode strings by default.
This means that individual characters can take up 1 or more bytes.
You put good old AnsiString in the code, but forgot one.

This means that the translation to Unicode is messing up your decryption, since with encryption even a single changed bit will mess everything up.

Stick with AnsiStrings throughout and you should be fine.

Change:

function Encrypt(DataToEncrypt: ansistring):ansistring;
var
  Cipher : TDCP_rijndael;
  Data: string;
  IV: array[0..15] of byte;      // the initialization vector
  i:Integer;
begin

to

// Encrypt a string and return the Base64 encoded result
function Encrypt(DataToEncrypt: AnsiString): AnsiString;
var
  Cipher: TDCP_rijndael;
  //Data: string; <<- change to ansistring
  Data: AnsiString;
  IV: array[0..15] of byte;      // the initialization vector
  i: Integer;

Upvotes: 4

Related Questions