A Warm Welcome to ASN.1 and DER

As cited in DDIA

Jacob Hoffman-Andrews. "A Warm Welcome to ASN.1 and DER." letsencrypt.org, April 2020. Archived at perma.cc/CYT2-GPQ8

How the page describes itself

A Warm Welcome to ASN.1 and DER - Let's Encrypt

This document provides a gentle introduction to the data structures and formats that define the certificates used in HTTPS. It should be accessible to anyone with a little bit of computer science experience and a bit of familiarity with certificates. An HTTPS certificate is a type of file, like any other file. Its contents follow a format defined by RFC 5280. The definitions are expressed in ASN.1…

From the page's own metadata at letsencrypt.org, 2026-08-29.

Link check

Status

Link checked and reachable (HTTP 200)

Format

text/html

Size

0.1 MB

Last checked

2026-08-29

Identifiers and archived copies

perma.cc

https://perma.cc/CYT2-GPQ8