My name is Philipp C. Heckel and I write about nerdy things.

Posts Tagged / TLS


  • Dec 13 / 2020
  • 0
Scripting, Security

Go: Calculating public key hashes for public key pinning in curl

Something occurred to me the other day. This is my blog, and that means I can write about whatever I want. Now you may think that’s totally obvious, but it’s not. For the longest time I wouldn’t blog about anything that I didn’t deem blog-worthy. Small things, like “this is a cool function I found” or “I learned this thing today”, were not blog-worthy in my mind for some reason.

Well today I am changing that. I like writing, but not necessarily so much that I always want to write a super long post. Sometimes, things should be short. Like this one.

So in this super short post I’m gonna show you a cool thing I figured out: How to calculate the the value that curls --pinnedpubkey option needs in Go.

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  • Aug 05 / 2018
  • 33
Linux, Security

Using Let’s Encrypt for internal servers

Let’s Encrypt is a revolutionary new certificate authority that provides free certificates in a completely automated process. These certificates are issued via the ACME protocol. Over the last 2 years or so, the Internet has widely adopted Let’s Encrypt — over 50% of the web’s SSL/TLS certificates are now issued by Let’s Encrypt.

But while there are many tools to automatically renew certificates for publicly available webservers (certbot, simp_le, I wrote about how to do that 3 years back), it’s hard to find any useful information about how to issue certificates for internal non Internet facing servers and/or devices with Let’s Encrypt.

This blog posts describes how to issue Let’s Encrypt certificates for internal servers. At Datto, we issued a certificate for each of our 65,000 90,000+ BCDR appliances using this exact mechanism.

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  • Dec 04 / 2015
  • 4
Administration, Code Snippets, Linux, Scripting, Security

Snippet 0x0D: Let’s Encrypt – 5 min guide to set up cronjob based certificate renewal

Let’s Encrypt was officially released to the open public today. That means the Internet can finally get free, trusted SSL/TLS certificates. This quick guide shows how to set up Let’s Encrypt with auto-renewal through a cronjob — using the simp_le client, an alternative client developed by one of the same authors who develop the official client.

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  • Aug 04 / 2013
  • 58
Security

Use SSLsplit to transparently sniff TLS/SSL connections – including non-HTTP(S) protocols

I recently demonstrated how to perform a man-in-the-middle attack on HTTP(S) connections using mitmproxy. While mitmproxy works just great for HTTP-based communication, it does not understand other TLS/SSL-based traffic such as FTPS, SMTP over SSL, IMAP over SSL or any other protocol wrapped in TLS/SSL.

SSLsplit is a generic transparent TLS/SSL proxy for performing man-in-the-middle attacks on all kinds of secure communication protocols. Using SSLsplit, one can intercept and save SSL-based traffic and thereby listen in on any secure connection.

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  • Jul 05 / 2013
  • 62
Android, Mobile, Security

How To: Sniff the WhatsApp password from your Android phone or iPhone

WhatsApp is a very popular SMS-like messenger for smartphones, but it’s unfortunately only available for smartphones right now. If you want to use other tools or write web applications that send or receive WhatsApp messages (e.g. WhatsAPI, was at https://github.com/venomous0x/WhatsAPI, site now defunct, July 2019), you have to find a way to sniff the WhatsApp password from your smartphone. Until recently, this password was just an MD5 hash of your IMEI (or MAC address), but that has changed when that was uncovered. Since then, the WhatsApp server assigns a password to each device/account when it first registers.

This tutorial demonstrates how to capture the WhatsApp password of your WhatsApp account using the SSL/TLS proxy mitmproxy. Once you have this password, you can use it to communicate with the WhatsApp servers directly or via a framework. This is the first part of a two-part tutorial. The second part demonstrates how to send and receive WhatsApp messages via PHP.

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