Pascal (Lazarus/Delphi)

SFTP Authenticate with a Private Key

Demonstrates the Chilkat SFtp.AuthenticatePk method, which authenticates the connected session using public-key authentication. The first argument is the username and the second is an SshKey private key. The matching public key must already be authorized for the account on the server.

Note: The private-key path is relative to the application's current working directory. Supply the path to your own key file.

Background: Public-key authentication is the standard for unattended SFTP transfers: the private key stays on the client, the server trusts the corresponding public key, and no reusable password crosses the wire. The SshKey object imports keys in several formats — this example loads an OpenSSH private key. For an encrypted key, set its Password property before importing.

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Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.SFtp,
  Chilkat.SshKey;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  sftp: TSFtp;
  port: Integer;
  privKey: TSshKey;
  keyText: string;

begin
  success := False;

  //  Demonstrates the SFtp.AuthenticatePk method, which authenticates the connected session using
  //  public-key authentication.  The 1st argument is the username and the 2nd is an SshKey private
  //  key.  The matching public key must already be authorized for the account on the server.

  sftp := TSFtp.Create;

  //  Step 1: Connect the SSH transport.  Port 22 is the usual port.
  port := 22;
  success := sftp.Connect('sftp.example.com',port);
  if (success = False) then
    begin
      WriteLn(sftp.LastErrorText);
      Exit;
    end;

  //  Load the SSH private key.  LoadText reads the file's text, which is then imported.
  privKey := TSshKey.Create;
  keyText := privKey.LoadText('qa_data/id_rsa');
  if (privKey.LastMethodSuccess = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;
  success := privKey.FromOpenSshPrivateKey(keyText);
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  success := sftp.AuthenticatePk('mySshLogin',privKey);
  if (success = False) then
    begin
      WriteLn(sftp.LastErrorText);
      Exit;
    end;

  //  Step 3: Open the SFTP subsystem.  This must be done after authentication and before any
  //  file or directory operations.
  success := sftp.InitializeSftp();
  if (success = False) then
    begin
      WriteLn(sftp.LastErrorText);
      Exit;
    end;

  WriteLn('Authenticated with a private key.');

  sftp.Disconnect();


  sftp.Free;
  privKey.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.