Delphi DLL

AES Encrypt and Decrypt a File

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
crypt: HCkCrypt2;
ivHex: PWideChar;
keyHex: PWideChar;
inFile: PWideChar;
outFile: PWideChar;
decrypt: HCkCrypt2;

begin
success := False;

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

crypt := CkCrypt2_Create();

CkCrypt2_putCryptAlgorithm(crypt,'aes');

// CipherMode may be "ecb" or "cbc"
CkCrypt2_putCipherMode(crypt,'cbc');

// KeyLength may be 128, 192, 256
CkCrypt2_putKeyLength(crypt,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.
CkCrypt2_putPaddingScheme(crypt,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';
CkCrypt2_SetEncodedIV(crypt,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';
CkCrypt2_SetEncodedKey(crypt,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 := CkCrypt2_CkEncryptFile(crypt,inFile,outFile);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

// For demonstration purposes, a different instance of the object will be used
// for decryption.
decrypt := CkCrypt2_Create();

// All settings must match to be able to decrypt:
CkCrypt2_putCryptAlgorithm(decrypt,'aes');
CkCrypt2_putCipherMode(decrypt,'cbc');
CkCrypt2_putKeyLength(decrypt,256);
CkCrypt2_putPaddingScheme(decrypt,0);
CkCrypt2_SetEncodedIV(decrypt,ivHex,'hex');
CkCrypt2_SetEncodedKey(decrypt,keyHex,'hex');

// Decrypt the .aes
inFile := '/Users/chilkat/testData/p7m/sample.pdf.aes';
outFile := '/Users/chilkat/testData/pdf/recovered.pdf';
success := CkCrypt2_CkDecryptFile(decrypt,inFile,outFile);
if (success = False) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(decrypt));
    Exit;
  end;

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

CkCrypt2_Dispose(crypt);
CkCrypt2_Dispose(decrypt);

end;