No domain left behind: Is Let's Encrypt democratizing encryption?

The 2013 National Security Agency revelations of pervasive monitoring have led to an "encryption rush" across the computer and Internet industry. To push back against massive surveillance and protect users' privacy, vendors, hosting and cloud providers have widely deployed encryption on their hardware, communication links, and applications. As a consequence, most web connections nowadays are encrypted. However, there is still a significant part of Internet traffic that is not encrypted. It has been argued that both costs and complexity associated with obtaining and deploying X.509 certificates are major barriers for widespread encryption, since these certificates are required to establish encrypted connections. To address these issues, the Electronic Frontier Foundation, Mozilla Foundation, the University of Michigan and a number of partners have set up Let's Encrypt (LE), a certificate authority that provides both free X.509 certificates and software that automates the deployment of these certificates. In this paper, we investigate if LE has been successful in democratizing encryption: we analyze certificate issuance in the first year of LE and show from various perspectives that LE adoption has an upward trend and it is in fact being successful in covering the lower-cost end of the hosting market.