(Delphi ActiveX) AES and CHACHA20 Encrypt/Decrypt Text

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.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
sb: TChilkatStringBuilder;
i: Integer;
crypt: TChilkatCrypt2;
ivHex: WideString;
keyHex: WideString;
bdEncrypted: TChilkatBinData;
sbOriginal: TChilkatStringBuilder;

begin
// 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 := TChilkatStringBuilder.Create(Self);
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;

Memo1.Lines.Add(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 := TChilkatCrypt2.Create(Self);

// 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 := TChilkatBinData.Create(Self);
success := crypt.EncryptSb(sb.ControlInterface,bdEncrypted.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// Examine the encrypted bytes:
Memo1.Lines.Add(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 := TChilkatStringBuilder.Create(Self);
success := crypt.DecryptSb(bdEncrypted.ControlInterface,sbOriginal.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// Examine the original data:
Memo1.Lines.Add(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.ControlInterface,bdEncrypted.ControlInterface);

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

Memo1.Lines.Add('----');
Memo1.Lines.Add('The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt.');
Memo1.Lines.Add(sbOriginal.GetAsString());
Memo1.Lines.Add('Success.');
end;