Delphi ActiveX Requires Chilkat v11.0.0+

RSASSA-PSS Sign String to Create Base64 PCKS7 Signature

See more Digital Signatures Examples

Signs a string to create a PKCS7 signature in the base64 encoding. The signature algorithm is RSASSA-PSS with SHA256. Delphi ActiveX

var
success: Integer;
crypt: TChilkatCrypt2;
pfx: TChilkatPfx;
cert: TChilkatCert;
originalText: WideString;
pkcs7sig: WideString;
opaqueSig: WideString;
origTxt: WideString;

begin
success := 0;

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

crypt := TChilkatCrypt2.Create(Self);

//  Get a digital certificate with private key from a .pfx
//  (Chilkat has many different ways to provide a cert + private key for siging.
//  Using a PFX is just one possible option.)
pfx := TChilkatPfx.Create(Self);
success := pfx.LoadPfxFile('qa_data/rsassa-pss/privatekey.pfx','PFX_PASSWORD');
if (success = 0) then
  begin
    Memo1.Lines.Add(pfx.LastErrorText);
    Exit;
  end;

//  Get the certificate to be used for signing.
//  (The typical case for a PFX is that it contains a cert with an associated private key,
//  as well as other certificates in the chain of authentication.  The cert with the private
//  key should be in the first position at index 0.)

cert := TChilkatCert.Create(Self);
success := pfx.CertAt(0,cert.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(pfx.LastErrorText);
    Exit;
  end;

crypt.SetSigningCert(cert.ControlInterface);

//  Indicate that RSASSA-PSS with SHA256 should be used.
crypt.SigningAlg := 'pss';
crypt.HashAlgorithm := 'sha256';

crypt.EncodingMode := 'base64';

//  Sign a string and return the base64 PKCS7 detached signature
originalText := 'This is a test';
pkcs7sig := crypt.SignStringENC(originalText);
Memo1.Lines.Add('Detached Signature:');
Memo1.Lines.Add(pkcs7sig);

//  This signature looks like this:
//  MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBgl .. YToLqEwTdU87ox5g7rvw==

//  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
//  then copy-and-paste the Base64 signature into the form and decode..

//  The signature can be verified against the original data like this:
success := crypt.VerifyStringENC(originalText,pkcs7sig);
Memo1.Lines.Add('Signature verified: ' + IntToStr(Ord(success)));
success := crypt.VerifyStringENC('Not the original text',pkcs7sig);
Memo1.Lines.Add('Signature verified: ' + IntToStr(Ord(success)));

//  Now we'll create an opaque signature (the opposite of a detached signature). 
//  An opaque signature is a PKCS7 message that contains both the original data and
//  the signature.  The verification process extracts the original data.
opaqueSig := crypt.OpaqueSignStringENC(originalText);
Memo1.Lines.Add('Opaque Signature:');
Memo1.Lines.Add(opaqueSig);

//  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
//  then copy-and-paste the Base64 signature into the form and decode..

//  We can verify and extract the original data:
origTxt := crypt.OpaqueVerifyStringENC(opaqueSig);
if (crypt.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add('Signature verification failed.');
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Signature verified.');
Memo1.Lines.Add('Extracted text:' + origTxt);