ECC P-256 problem (KSeF)

VCL TMS Cryptography Pack
21

Hi Bermard.

our activities have crossed on the fly :smile: .

I just added this routine:

procedure TECCEncSign.FromPrivateKeyStringList(ts: TStringList);
const RSA_FILE = 0;ECC_FILE = 1;
varKeyStr: string;
I: Integer;
Conv: TConvert;
ASN: TASN1;
fileType: integer;
pubK, privK: TBytes;
LocalType: TConvertType;
begin
ASN := TASN1.Create;
ASN.Password := Self.Password;
LocalType := Self.OutputFormat;
Self.OutputFormat := raw;
try

  fileType := ECC_FILE;
  if ts.count <> 0 then begin
    if (ts.Strings[0] = '-----BEGIN PRIVATE KEY-----') then begin
      if (ts.Strings[ts.count - 1] <> '-----END PRIVATE KEY-----') then
        raise ECryptoPack.Create('This is not a valid private key file [01]')
    end
    else if (ts.Strings[0] = '-----BEGIN RSA PRIVATE KEY-----') then begin
      if (ts.Strings[ts.count - 1] <> '-----END RSA PRIVATE KEY-----') then
        raise ECryptoPack.Create('This is not a valid RSA private key file [02]')
    end
    else if (ts.Strings[0] = '-----BEGIN ENCRYPTED PRIVATE KEY-----') then begin
      if (ts.Strings[ts.count - 1] <> '-----END ENCRYPTED PRIVATE KEY-----') then
        raise ECryptoPack.Create('This is not a valid encrypted private key file [03]')
    end
    else if (ts.Strings[0] = '-----BEGIN EC PRIVATE KEY-----') then begin
      if (ts.Strings[ts.count - 1] <> '-----END EC PRIVATE KEY-----') then
        raise ECryptoPack.Create('This is not a valid EC private key file [04]');
      fileType := ECC_FILE;
    end
    else
      raise ECryptoPack.Create('This is not a private key file');

    KeyStr := '';
    for I := 1 to ts.count - 2 do
      KeyStr := KeyStr + ts.Strings[I];
    // Convert from base64 to raw ASN.1
    Conv := TConvert.Create;
    Conv.Base64ToChar(KeyStr, KeyStr);
    Conv.Free;
    if fileType = ECC_FILE then
      Asn.ExtractECCPrivateKey(KeyStr)
    else
      raise ECryptoPack.Create('This is not an EC private key file');
  end;

  FPublicKey  := ASN.ECKeySet.PublicKey;
  FPrivateKey := ASN.ECKeySet.PrivateKey;
  self.ECCType := ASN.ECKeySet.ECCType;

  if (self.ECCType <> ex25519) and (self.ECCType <> ex448) and
    (self.ECCType <> cc25519) and (self.ECCType <> cc448)  then
    self.FCurve.SetOpenSSL(true)
  else begin
    privK := conv.StringToTBytes(FPrivateKey);
    SetLength(pubK, Length(FPrivateKey));
    self.FCurve.GeneratePublicKey(pubK, privK);
    FPublicKey := conv.TBytesToString(pubK);
  end;

finally
  ASN.Free;
end;
Self.OutputFormat := LocalType;
end;

And this is basically the copy of procedure TECCEncSign.FromPrivateKeyFile
but without loading the file.

And then procedure TECCEncSign.FromPrivateKeyFile can be simplified to just load the ts variable and call procedure FromPrivateKeyStringList(ts);

Anyway, I will follow your official implementation when it’s available.

Thank you so much for your help.

Kind regards

Arek

22

Funny!

I have cleaned up the initial FromPrivateKeyFile, as many lines are irrelevant for EC keys and my function is a lot simpler, but similar.

23

Great! I will get the update as soon as it is available.

Thanks again!