Lets Encrypt = Free 100% HTTPS
Let's Encryptis a certificate authority that provides free X.509 certificates for Transport Layer Security (TLS) encryption via an automated process designed to eliminate the hitherto complex process of manual creation, validation, signing, installation, and renewal of certificates for secure websites.
Let’s Encrypt is a free, automated, and open certificate authority brought to you by the non-profit Internet Security Research Group (ISRG).
1 million March 8, 2016，Milestone: 100 Million Certificates Issued, Jun 28, 2017. ⬆️
Now Wildcard Certificates has supported on March 13, 2018. But Let’s Encrypt will generate an ECDSA root and intermediates which can be used to sign end-entity certificates by Q3 2018. See Also Upcoming Features
ACME: Automatic Certificate Management Environment, ACME v2 API Enabled: March 13, 2018.
Detailed Working Principle can found here How It Works. Core Work is Domain Validation:
About Domain Validation:
Let’s Encrypt identifies the server administrator by public key. The first time the agent software interacts with Let’s Encrypt, it generates a new key pair and proves to the Let’s Encrypt CA that the server controls one or more domains. This is similar to the traditional CA process of creating an account and adding domains to that account.
To kick off the process, the agent asks the Let’s Encrypt CA what it needs to do in order to prove that it controls
example.com. The Let’s Encrypt CA will look at the domain name being requested an