The group behind the Let's Encrypt certificate authority (CA) says that its name could be in doubt thanks to rival CA Comodo Group.

The Internet Security Research Group (ISRG) says that it is currently locked in a conflict with Comodo, who it claims is trying to trademark the "Let's Encrypt" name despite its previous filings on the term.

"Some months ago, it came to our attention that Comodo Group Inc is attempting to register at least three trademarks for the term 'Let's Encrypt,' for a variety of CA-related services," ISRG said.

"These trademark applications were filed long after the Internet Security Research Group started using the name Let's Encrypt publicly in November of 2014, and despite the fact Comodo's 'intent to use' trademark filings acknowledge that it has never used 'Let's Encrypt' as a brand."

ISRG has long used the "Let's Encrpyt" name for its open HTTPS push. The campaign lets webmasters register secured domains by freely granting TLS (transport layer security) certificates.

The system allows smaller publishers to secure their sites and ensure that traffic goes over secure channels.

Now, ISRG says, Comodo is attempting to move in on its operation by looking for a trademark on the "Let's Encrypt" name and, potentially, shutting down ISRG's operation using that name.

"Since March of 2016 we have repeatedly asked Comodo to abandon their 'Let's Encrypt' applications, directly and through our attorneys, but they have refused to do so," ISRG says.

"We are clearly the first and senior user of 'Let's Encrypt' in relation to Internet security, including SSL [secure sockets layer]/TLS certificates – both in terms of length of use and in terms of the widespread public association of that brand with our organization."

At the time of publishing, Comodo had yet to respond to a request for comment. ®