code: func fixCertIfNeed(cert []byte) {
  	h := sha256.Sum256(cert)
  	switch hex.EncodeToString(h[:]) {
  	case
  		"349bca1031f8c82c4ceca38b9cebf1a69df9fb3b94eed99eb3fb9aa3822d26e8",
  		"dd574527df608e47ae45fbba75a2afdd5c20fd94a02419381813cd55a2a3398f",
  		"1d8764f0f7cd1352df6150045c8f638e517270e8b5dda1c63ade9c2280240cae",
  		"d0edc9a91a1677435a953390865d208c55b3183c6759c9b5a7ff494c322558eb",
  		"6073c436dcd064a48127ddbf6032ac1a66fd59a0c24434f070d4e564c124c897",
  		"ca993121846c464d666096d35f13bf44c1b05af205f9b4a1e00cf6cc10c5e511":
  
  		// clear the offending byte.
  		cert[len(cert)-257] = 0
  	}
  }
docs: // fixCertIfNeed fixes broken certificates described in
  // https://github.com/Yubico/php-u2flib-server/blob/master/src/u2flib_server/U2F.php#L84