Delphi DLL

Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

See more RSA Examples

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

Delphi 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;
pkey: HCkPrivateKey;
rsa: HCkRsa;
strData: PWideChar;
base64Sig: PWideChar;

begin
success := False;

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

pkey := CkPrivateKey_Create();

// Load the private key from an RSA PEM file:
success := CkPrivateKey_LoadPemFile(pkey,'myKey.pem');

rsa := CkRsa_Create();

// Import the private key into the RSA component:
success := CkRsa_UsePrivateKey(rsa,pkey);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

// OpenSSL uses BigEndian byte ordering:
CkRsa_putLittleEndian(rsa,False);

// The resulting signature will be a Base64 string:
CkRsa_putEncodingMode(rsa,'base64');

// For simplicity, we're not loading
// the data to be signed from a file.  We are instead simply
// using a literal string value.  
strData := 'This is the text to be signed.';

// Hash the input using MD5, and then sign the hash:
// Other valid hash algorithm choices are "md2" and "sha-1".
base64Sig := CkRsa__signStringENC(rsa,strData,'md5');

Memo1.Lines.Add(base64Sig);

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

CkPrivateKey_Dispose(pkey);
CkRsa_Dispose(rsa);

end;