Pascal (Lazarus/Delphi)

AES and CHACHA20 Encrypt/Decrypt Text

See more Encryption Examples

Demonstrates the use of the new EncryptSb and DecryptSb methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt the contents of StringBuilder objects.

Note: This example requires Chilkat v9.5.0.67 or greater.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.StringBuilder,
  Chilkat.BinData,
  Chilkat.Crypt2;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  sb: TStringBuilder;
  i: Integer;
  crypt: TCrypt2;
  ivHex: string;
  keyHex: string;
  bdEncrypted: TBinData;
  sbOriginal: TStringBuilder;

begin
  success := False;

  //  This example assumes the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  //  First build a string to be encrypted
  sb := TStringBuilder.Create;
  i := 1;
  while i < 10 do
    begin
      sb.AppendInt(i);
      sb.Append(' the quick brown fox jumped over the lazy dog.' + #13#10);
      i := i + 1;
    end;

  WriteLn(sb.GetAsString());

  //  The string to be encrypted looks like this:

  //  1 the quick brown fox jumped over the lazy dog.
  //  2 the quick brown fox jumped over the lazy dog.
  //  3 the quick brown fox jumped over the lazy dog.
  //  4 the quick brown fox jumped over the lazy dog.
  //  5 the quick brown fox jumped over the lazy dog.
  //  6 the quick brown fox jumped over the lazy dog.
  //  ...

  crypt := TCrypt2.Create;

  //  Specify the encryption to be used.
  //  First we'll do AES-128 CBC
  crypt.CryptAlgorithm := 'aes';
  crypt.CipherMode := 'cbc';
  crypt.KeyLength := 128;

  ivHex := '000102030405060708090A0B0C0D0E0F';
  crypt.SetEncodedIV(ivHex,'hex');

  keyHex := '000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F';
  crypt.SetEncodedKey(keyHex,'hex');

  //  When EncryptSb is called, the contents of the source (sb)
  //  remains unmodified.  The encrypted bytes are written into bdEncrypted.
  //  If bdEncrypted already contained data, it is replaced with the encrypted bytes.
  bdEncrypted := TBinData.Create;
  success := crypt.EncryptSb(sb,bdEncrypted);
  if (success <> True) then
    begin
      WriteLn(crypt.LastErrorText);
      Exit;
    end;

  //  Examine the encrypted bytes:
  WriteLn(bdEncrypted.GetEncoded('base64_mime'));

  //  Sample encrypted data:

  //  0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
  //  df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
  //  EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
  //  g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
  //  PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
  //  2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
  //  eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
  //  H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

  //  Decrypt to restore back to the original:
  sbOriginal := TStringBuilder.Create;
  success := crypt.DecryptSb(bdEncrypted,sbOriginal);
  if (success <> True) then
    begin
      WriteLn(crypt.LastErrorText);
      Exit;
    end;

  //  Examine the original data:
  WriteLn(sbOriginal.GetAsString());

  //  ----------------------------------------------------------------------------------
  //  To do chacha20 encryption, just change the settings:

  crypt.CryptAlgorithm := 'chacha20';
  crypt.KeyLength := 256;
  //  The initial count is the initial block counter for the chacha20 algorithm.
  //  It can be any integer, but must be set to the same when decrypting.
  crypt.InitialCount := 22;

  //  EncryptSb completely replaces the contents of bdEncrypted.
  success := crypt.EncryptSb(sb,bdEncrypted);

  //  However.. DecryptSb appends the decrypted text to whatever may
  //  have already existed within sbOriginal.
  success := crypt.DecryptSb(bdEncrypted,sbOriginal);

  WriteLn('----');
  WriteLn('The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt.');
  WriteLn(sbOriginal.GetAsString());
  WriteLn('Success.');


  sb.Free;
  crypt.Free;
  bdEncrypted.Free;
  sbOriginal.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.