(Delphi DLL) Encrypt with Chilkat, Decrypt with OpenSSL

Demonstrates how to RSA encrypt a string using Chilkat, and then shows the corresponding OpenSSL command to RSA decrypt. The OpenSSL command to decrypt is as follows:

openssl rsautl -decrypt -inkey VP_Private.pem -in rsa_encrypted.bin -out original.txt

Note: This example requires Chilkat v11.0.0 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, FileAccess, Rsa, PublicKey, CkByteData;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
rsa: HCkRsa;
key: HCkPublicKey;
strToEncrypt: PWideChar;
usePrivateKey: Boolean;
encryptedBytes: HCkByteData;
fac: HCkFileAccess;

begin
success := False;

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

rsa := CkRsa_Create();

// Note: RSA encryption uses the public key.  
// RSA decryption uses the private key.
// The reason is that the public key can be freely provided to anybody.  This allows anybody
// to send an encrypted message to the private key owner, and only the private key owner 
// can decrypt.
key := CkPublicKey_Create();

// Load an RSA public key from a PEM file:
success := CkPublicKey_LoadFromFile(key,'qa_data/pem/VP_Public.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(key));
    Exit;
  end;

// Load the public key into the RSA object.
success := CkRsa_UsePublicKey(rsa,key);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

strToEncrypt := '00000000;XYZ2-3BHQ-ABCD-MMVV;6MY1-GHJK-9LRR;0';

// The LittleEndian property is False by default, but it is set here
// anyway to show that LittleEndian byte ordering is required for OpenSSL compatibility.
CkRsa_putLittleEndian(rsa,False);

usePrivateKey := False;
encryptedBytes := CkByteData_Create();
success := CkRsa_EncryptString(rsa,strToEncrypt,usePrivateKey,encryptedBytes);
if (CkRsa_getLastMethodSuccess(rsa) = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

// The OpenSSL command to decrypt would be this:
// openssl rsautl -decrypt -inkey VP_Private.pem -in rsa_encrypted.bin -out original.txt

fac := CkFileAccess_Create();
success := CkFileAccess_WriteEntireFile(fac,'qa_output/rsa_encrypted.bin',encryptedBytes);
if (success = False) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(fac));
    Exit;
  end;

Memo1.Lines.Add('RSA Encryption Succeeded.');

CkRsa_Dispose(rsa);
CkPublicKey_Dispose(key);
CkByteData_Dispose(encryptedBytes);
CkFileAccess_Dispose(fac);

end;