The DigitalGov University has several presentations on HTTPS from the General Services Administration:

• An Introduction to HTTPS for Beginners (June 2015), by Eric Mill and Gray Brooks. This introduction runs a little over an hour, and covers how HTTP and the web work, what HTTPS does to help, and why we should use it for everything.

• Implementing HTTPS (July 2015), by Eric Mill and Gray Brooks. A more detailed explanation of how HTTPS works, how to migrate a website to HTTPS, the technical concepts you should be aware of when implementing HTTPS, and new and upcoming advances in HTTPS.

• Migrating to HTTPS (July 2016), by Eric Mill and Timothy Badaczewski. This presentation covers common issues common to federal HTTPS migrations, including: HTTP Strict Transport Security (HSTS), getting certificates, mixed content, and search engine optimization (SEO).

• crt.sh - An open source public viewer for Certificate Transparency logs. For example, you can view all publicly logged whitehouse.gov certificates.
• certspotter - An open source tool for monitoring issuance of certificates that appear in Certificate Transparency logs.
• certlint - An open source tool that reviews x.509 certificates for compliance with CA/Browser Forum requirements and various RFCs.
• ssllabs-scan - Command line tool for the API for SSL Labs, a universally referenced HTTPS evaluation and grading tool for public-facing websites.
• site-inspector - Scan a domain for various web/HTTP-related properties, including HTTPS support.
• mixed-content-scan - Command line tool for walking over a website and scanning for the use of insecure resources.

• DigitalGov: Secure Central Hosting for the Digital Analytics Program
• FTC: FTC.gov is now HTTPS by default
• Privacy and Civil Liberties Oversight Board: PCLOB.gov is now HTTPS by default
• CIA: Statement on CIA Website Enhancement from 2006
• 18F: Why we use HTTPS for every .gov we make
• 18F: The first .gov domains hardcoded into your browser as all-HTTPS