generating electronic media content including the URL;

generating a Certificate Signing Request (CSR) for the URL by encoding a username in a certificate common name of the CSR and encoding the URL in a Subject Alternative Name (SAN) field of the CSR;

sending the CSR to a certificate signing server;

receiving a signed certificate corresponding to the CSR from the certificate signing server, wherein the signed certificate includes data to authenticate that the URL is sent by a sender client;

encoding, according to a public key cryptographic standard, the signed certificate as metadata in the electronic media content and/or an identifier associated with the signed certificate as metadata in the electronic media content, wherein the electronic media content includes at least two URLs, wherein the SAN field includes the at least two URLs, and wherein the encoding includes encoding the metadata including the at least two URLs; and

validating the URL in the electronic media content without user intervention based on the signed certificate encoded as metadata to ensure that the URL is not modified since creation, wherein validating the URL comprises:

detecting, in the metadata, the encoded signed certificate and/or the encoded serial number associated with the signed certificate,

matching the URL in the electronic media content to a domain name in a SAN field of the encoded signed certificate, and

validating the encoded signed certificate prior to accessing the URL.