Editing Public key infrastructure (section)

== Criticism ==
{{see also|X.509#Security|Comodo Group#2011 breach incident|Diginotar#Issuance of fraudulent certificates}}
Some argue that purchasing certificates for securing websites by [[Transport Layer Security|SSL/TLS]] and securing software by [[code signing]] is a costly venture for small businesses.<ref>{{cite web |url=https://www.forbes.com/sites/richardstiennon/2013/05/14/should-we-abandon-digital-certificates-or-learn-to-use-them-effectively |title=Should We Abandon Digital Certificates, Or Learn to Use Them Effectively? |work=[[Forbes]]}}</ref>  However, the emergence of free alternatives, such as [[Let's Encrypt]], has changed this. [[HTTP/2]], the latest version of HTTP protocol, allows unsecured connections in theory;  in practice, major browser companies have made it clear that they would support this protocol only over a PKI secured [[Transport Layer Security|TLS]] connection.<ref>{{cite web |url=https://http2.github.io/faq/ |title=HTTP/2 Frequently Asked Questions |via=Github |work=HTTP/2 wiki}}</ref> Web browser implementation of HTTP/2 including [[Google Chrome|Chrome]], [[Firefox]], [[Opera (web browser)|Opera]], and [[Microsoft Edge|Edge]] supports HTTP/2 only over TLS by using the [[ALPN]] extension of the TLS protocol. This would mean that, to get the speed benefits of HTTP/2, website owners would be forced to purchase SSL/TLS certificates controlled by corporations.

Currently the majority of web browsers are shipped with pre-installed [[Public key certificate#Intermediate certificate|intermediate certificates]] issued and signed by a certificate authority, by public keys certified by so-called [[root certificates]]. This means browsers need to carry a large number of different certificate providers, increasing the risk of a key compromise.<ref>{{cite web |title=Root Certificate vs Intermediate Certificates |url=https://aboutssl.org/root-certificates-vs-intermediate-certificates/ |access-date=2022-05-02 |website=About SSL |language=en-US}}</ref>

When a key is known to be compromised, it could be fixed by revoking the certificate, but such a compromise is not easily detectable and can be a huge security breach. Browsers have to issue a security patch to revoke intermediary certificates issued by a compromised root certificate authority.<ref>{{cite web |work=Microsoft Security Advisory |title=Fraudulent Digital Certificates could allow spoofing |url=http://support.microsoft.com/kb/2524375 |date=March 23, 2011 |access-date=2011-03-24|publisher=Microsoft}}</ref>