Delphi DLL

RSA Signature using Private Key from .snk File

See more RSA Examples

A .snk file (Strong Name Key file) is a file format used in the .NET ecosystem to store an RSA public/private key pair. This key pair is typically used for strong-naming assemblies, which is a process of signing .NET assemblies to ensure their integrity and to uniquely identify them.

This example loads a private key from a .snk file and creates an RSA signature.

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;
rsa: HCkRsa;
xmlStr: PWideChar;
privKey: HCkPrivateKey;
sigBase64: PWideChar;

begin
success := False;

rsa := CkRsa_Create();

// Load the .snk and return the private key as XML.
xmlStr := CkRsa__snkToXml(rsa,'./test.snk');
if (CkRsa_getLastMethodSuccess(rsa) = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

privKey := CkPrivateKey_Create();
success := CkPrivateKey_LoadXml(privKey,xmlStr);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

success := CkRsa_UsePrivateKey(rsa,privKey);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

// Sign the SHA-256 hash of the utf-8 byte representation of the contents of sb
// Return the signature in base64 format.
CkRsa_putEncodingMode(rsa,'base64');
CkRsa_putCharset(rsa,'utf-8');
sigBase64 := CkRsa__signStringENC(rsa,'This is the text to be hashed and signed.','sha256');
if (CkRsa_getLastMethodSuccess(rsa) = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

Memo1.Lines.Add('RSA signature as base64: ' + sigBase64);

CkRsa_Dispose(rsa);
CkPrivateKey_Dispose(privKey);

end;