Let's Encrypt is a free, automated, and open certificate authority brought to you by the nonprofit Internet Security Research Group (ISRG). Read all about our nonprofit work this year in our 2023 Annual Report.
Happy birthday to Let’s Encrypt !
Huge thanks to everyone involved in making HTTPS available to everyone for free !
If you are the CA, you can sign a new certificate yourself for google.com and the browser will accept it. It’s effectively allows MITM for any certificate. Worse, it’s not even limited to certificates under that CA. The browser has no way of knowing there’s 2 “valid” certs at once, and in fact that is allowed regardless (multiple servers with different instances of the SSL cert is a possibility).
Certificate pinning might save things, since that will force the same certificate as was previously used, but I’m not sure this is a common default.
If you are the CA, you can sign a new certificate yourself for google.com and the browser will accept it. It’s effectively allows MITM for any certificate. Worse, it’s not even limited to certificates under that CA. The browser has no way of knowing there’s 2 “valid” certs at once, and in fact that is allowed regardless (multiple servers with different instances of the SSL cert is a possibility).
Certificate pinning might save things, since that will force the same certificate as was previously used, but I’m not sure this is a common default.