(Delphi ActiveX) AES Encrypt and Decrypt a File

Delphi ActiveX demonstrates how to AES encrypt a file of any size, and then decrypt.

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
crypt: TChilkatCrypt2;
ivHex: WideString;
keyHex: WideString;
inFile: WideString;
outFile: WideString;
success: Integer;
decrypt: TChilkatCrypt2;

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

crypt := TChilkatCrypt2.Create(Self);

crypt.CryptAlgorithm := 'aes';

// CipherMode may be "ecb" or "cbc"
crypt.CipherMode := 'cbc';

// KeyLength may be 128, 192, 256
crypt.KeyLength := 256;

// The padding scheme determines the contents of the bytes
// that are added to pad the result to a multiple of the
// encryption algorithm's block size.  AES has a block
// size of 16 bytes, so encrypted output is always
// a multiple of 16.
crypt.PaddingScheme := 0;

// An initialization vector is required if using CBC mode.
// ECB mode does not use an IV.
// The length of the IV is equal to the algorithm's block size.
// It is NOT equal to the length of the key.
ivHex := '000102030405060708090A0B0C0D0E0F';
crypt.SetEncodedIV(ivHex,'hex');

// The secret key must equal the size of the key.  For
// 256-bit encryption, the binary secret key is 32 bytes.
// For 128-bit encryption, the binary secret key is 16 bytes.
keyHex := '000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F';
crypt.SetEncodedKey(keyHex,'hex');

// Encrypt a file, producing the .aes as output.
// The input file is unchanged, the output .aes contains the encrypted
// contents of the input file.

// Note: The .aes output file has no file format.  It is simply a stream
// of bytes that resembles random binary data.
inFile := '/Users/chilkat/testData/pdf/sample.pdf';
outFile := '/Users/chilkat/testData/p7m/sample.pdf.aes';
success := crypt.CkEncryptFile(inFile,outFile);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// For demonstration purposes, a different instance of the object will be used
// for decryption.
decrypt := TChilkatCrypt2.Create(Self);

// All settings must match to be able to decrypt:
decrypt.CryptAlgorithm := 'aes';
decrypt.CipherMode := 'cbc';
decrypt.KeyLength := 256;
decrypt.PaddingScheme := 0;
decrypt.SetEncodedIV(ivHex,'hex');
decrypt.SetEncodedKey(keyHex,'hex');

// Decrypt the .aes
inFile := '/Users/chilkat/testData/p7m/sample.pdf.aes';
outFile := '/Users/chilkat/testData/pdf/recovered.pdf';
success := decrypt.CkDecryptFile(inFile,outFile);
if (success = 0) then
  begin
    Memo1.Lines.Add(decrypt.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Success!');
end;