title: Warning: openssl_pkcs7_sign: error creating PKCS7 structure
body: <p>We are trying to sign the PAN no. with Digital Signature. We are taking the PAN No. in in.txt file but we are getting error -</p>
  
  <p><strong>Warning: openssl_pkcs7_sign(): error creating PKCS7 structure!</strong></p>
  
  <pre><code>openssl_pkcs7_sign(realpath("in.txt"), "out.txt",
                  'file://'.realpath('digitalsign.cer'),
                 'file://'.realpath('private_key.pem'),
                  array (), PKCS7_NOSIGS
              );  
  </code></pre>
  
  <p>Kindly suggest what we can do to resolve this issue.</p>