(Delphi DLL) RSA Decrypt using PEM

This example demonstrates decryping RSA encrypted data that is base64 encoded. It uses a private key loaded from a PEM file.

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, PrivateKey, Rsa;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
rsa: HCkRsa;
key: HCkPrivateKey;
encryptedStr: PWideChar;
usePrivateKey: Boolean;
decryptedStr: PWideChar;

begin
success := False;

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

rsa := CkRsa_Create();

key := CkPrivateKey_Create();

// Load an RSA private key from an unencrypted PEM file:
// (To load from an encrypted PEM file, call LoadEncryptedPemFile instead.)

success := CkPrivateKey_LoadPemFile(key,'qa_data/rsa/decryptTest/priv.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(key));
    Exit;
  end;

// Make the key available to the RSA object
success := CkRsa_UsePrivateKey(rsa,key);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

encryptedStr := 'pP9XFJEsGgxPNHEgNiLB5H5ksCOXDk/G49BPTog1jKLAhYofV4UTH5k2TOYiqRnDnKs8+8uPoN/IxdiGXvuYG8HRzN0HtkhoZO/AxeyaB9S7eddCUlT0Pl2PEB2yQ9HG5rM7jqYOD6MAM4cuX7hqT8fa8tbzJzmBwdfFDBz94bwQjULHiO+gklIBC4vhkXT4yjuvEjxTAKU6tJeZYkBooJNdS/vE5RZRpuF6bGZU41Qc17qFR+iReBq+9f8IMmw8WR8fMbOCaygOfFS1nw7JVsIMGsAIXS8rUaJ/2DfGPfQx5HCiVtTOreGYRUI3esAQjnvUCnavZyQgs53nl7e2aA==';

CkRsa_putEncodingMode(rsa,'base64');

usePrivateKey := True;
decryptedStr := CkRsa__decryptStringENC(rsa,encryptedStr,usePrivateKey);

Memo1.Lines.Add('Decrypted:');
Memo1.Lines.Add(decryptedStr);

CkRsa_Dispose(rsa);
CkPrivateKey_Dispose(key);

end;