Is there a chance to deal with unknown format of private key & certificate?

I'm working on a Delphi project where I will sign an invoice. I tested some OpenSSL Delphi ports and I had success in signing and verifying data. The problem is that I can't read either the key or the certificate files. I think there is a problem with key and certificate formats.

Private key (private-key.pem)

MHQCAQEEIP0tXvA0mhzTBgjZaAGt+V3tWIr79nG/gs56jKFJb6gboAcGBSuBBAAKoUQDQgAE+39UxFUCaF5p51RTvwXL+YODEpITlTdI27S72pSPJEAjQs2jBb1sLS/xg8/y5555+d19KoLmLo6gMrxvINXaHw==

Certificate (cert.pem)

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

Code to read private key

    bp := BIO_new_file(PAnsiChar(PrivKeyFile), 'r');
    if CheckError() then Exit;
    try
      FPrivateKeyData := PEM_read_bio_PrivateKey(bp, nil, nil, PAnsiChar(FCertPassword));
      if CheckError() then Exit;
    finally
      BIO_free(bp);
    end;

Code to read certificate

  bp := BIO_new_file(PAnsiChar(certFile), 'r');
  if CheckError then Exit;
  try
   _x509 := PEM_read_bio_X509(bp, nil, nil, PAnsiChar(FCertPassword));
   if CheckError then Exit;
  finally
    BIO_free(bp);
  end;

Error Message in both cases

error:0906D06C:PEM routines:PEM_read_bio:no start line

If files format is not accepted by OpenSSL, is there any way to convert files format so I can use them with OpenSSL library?

Solution

PEM IS NOT JUST BASE64. Your files names say .pem and you try to read them with routines that handle PEM, but they aren't PEM. PEM is base64 (of certain data types) with linebreaks and with header/trailer lines -- these are not optional; see rfc7468. Your previous Q had these correct and only the 'type' in the header/trailer wrong.

Add header/trailer lines and linebreaks as follows (edit: corrected privatekey type) and your files will work with your code:

Alternatively, you can decode the base64 to binary and then use the routines that parse binary rather than PEM, for this case d2i_ECPrivateKey and d2i_x509.

Note this privatekey is not encrypted, so you don't actually need the password (it is ignored).

Meta: I'm not sure this is really programming or development, but I needed formatting so I answered. If Q is closed, I will delete if requested.