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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, StringBuilder, BinData, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sb: HCkStringBuilder;
i: Integer;
crypt: HCkCrypt2;
ivHex: PWideChar;
keyHex: PWideChar;
bdEncrypted: HCkBinData;
sbOriginal: HCkStringBuilder;

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 := CkStringBuilder_Create();
i := 1;
while i < 10 do
  begin
    CkStringBuilder_AppendInt(sb,i);
    CkStringBuilder_Append(sb,' the quick brown fox jumped over the lazy dog.' + #13#10);
    i := i + 1;
  end;

Memo1.Lines.Add(CkStringBuilder__getAsString(sb));

// 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 := CkCrypt2_Create();

// Specify the encryption to be used.
// First we'll do AES-128 CBC
CkCrypt2_putCryptAlgorithm(crypt,'aes');
CkCrypt2_putCipherMode(crypt,'cbc');
CkCrypt2_putKeyLength(crypt,128);

ivHex := '000102030405060708090A0B0C0D0E0F';
CkCrypt2_SetEncodedIV(crypt,ivHex,'hex');

keyHex := '000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F';
CkCrypt2_SetEncodedKey(crypt,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 := CkBinData_Create();
success := CkCrypt2_EncryptSb(crypt,sb,bdEncrypted);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

// Examine the encrypted bytes:
Memo1.Lines.Add(CkBinData__getEncoded(bdEncrypted,'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 := CkStringBuilder_Create();
success := CkCrypt2_DecryptSb(crypt,bdEncrypted,sbOriginal);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

// Examine the original data:
Memo1.Lines.Add(CkStringBuilder__getAsString(sbOriginal));

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

CkCrypt2_putCryptAlgorithm(crypt,'chacha20');
CkCrypt2_putKeyLength(crypt,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.
CkCrypt2_putInitialCount(crypt,22);

// EncryptSb completely replaces the contents of bdEncrypted.
success := CkCrypt2_EncryptSb(crypt,sb,bdEncrypted);

// However.. DecryptSb appends the decrypted text to whatever may
// have already existed within sbOriginal.
success := CkCrypt2_DecryptSb(crypt,bdEncrypted,sbOriginal);

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(CkStringBuilder__getAsString(sbOriginal));
Memo1.Lines.Add('Success.');

CkStringBuilder_Dispose(sb);
CkCrypt2_Dispose(crypt);
CkBinData_Dispose(bdEncrypted);
CkStringBuilder_Dispose(sbOriginal);

end;