Delphi DLL Requires Chilkat v11.0.0+

RSA Sign with PKCS8 Encrypted Key

See more RSA Examples

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Delphi DLL

var
success: Boolean;
privKey: HCkPrivateKey;
rsa: HCkRsa;
strData: PWideChar;
hexSig: PWideChar;
cert: HCkCert;
pubKey: HCkPublicKey;
rsa2: HCkRsa;

begin
success := False;

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

privKey := CkPrivateKey_Create();

//  Load the private key from an RSA PEM file:
success := CkPrivateKey_LoadAnyFormatFile(privKey,'raul_privateKey.key','a0123456789');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

rsa := CkRsa_Create();

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

//  This example will sign a string, and receive the signature
//  in a hex-encoded string.  Therefore, set the encoding mode
//  to "hex":
CkRsa_putEncodingMode(rsa,'hex');

strData := 'This is the string to be signed.';

//  Sign the string using the sha256 hash algorithm.
//  Other valid choices are sha1, sha384, sha512 and others.
hexSig := CkRsa__signStringENC(rsa,strData,'sha256');
if (CkRsa_getLastMethodSuccess(rsa) = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

Memo1.Lines.Add(hexSig);

//  Now verify with the public key.
//  This example shows how to use the public key from 
//  a digital certificate (.cer file)
cert := CkCert_Create();
success := CkCert_LoadFromFile(cert,'raul_publicKey.cer');
if (success = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

pubKey := CkPublicKey_Create();
CkCert_GetPublicKey(cert,pubKey);

rsa2 := CkRsa_Create();
success := CkRsa_UsePublicKey(rsa2,pubKey);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa2));
    Exit;
  end;

//  Verify the signature against the original data:
CkRsa_putEncodingMode(rsa2,'hex');
success := CkRsa_VerifyStringENC(rsa2,strData,'sha256',hexSig);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa2));
    Exit;
  end;

Memo1.Lines.Add('Signature verified!');

//  Verify with incorrect data:
success := CkRsa_VerifyStringENC(rsa2,'something else','sha256',hexSig);
if (success <> True) then
  begin
    Memo1.Lines.Add('Signature not verified! (which was expected in this case)');
  end
else
  begin
    Memo1.Lines.Add('Hmmm... that''s not right...');
  end;

CkPrivateKey_Dispose(privKey);
CkRsa_Dispose(rsa);
CkCert_Dispose(cert);
CkPublicKey_Dispose(pubKey);
CkRsa_Dispose(rsa2);