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

Posts Tagged / SSL


  • Dec 13 / 2020
  • Comments Off on Go: Calculating public key hashes for public key pinning in curl
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
  • 35
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 my work, we issued a certificate for each of our 65,000 90,000+ BCDR appliances using this exact mechanism.

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  • Oct 30 / 2014
  • 1
Code Snippets, Programming

Snippet 0x08: HTTP Basic Auth for secure WebSocket connections (with Undertow)

For my open source file sync software Syncany, I use the embedded web server and web socket server Undertow to provide a websocket and REST based interface by the Syncany daemon. Syncany clients (such as the GUI, or potentially a web interface) connect to this daemon, send requests and receive asynchronous events. Syncany’s GUI client also uses the Undertow websocket client to connect to the above mentioned daemon.

To authenticate the websocket client with the daemon, the simple HTTP basic authentication mechanism over HTTPS is used. This tiny post shows you how to authenticate against a websocket server with HTTP basic auth using the Undertow websocket client.

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  • Oct 17 / 2014
  • Comments Off on Snippet 0x06: Disable SSLv3 in Firefox to protect against POODLE attack
Code Snippets, Security

Snippet 0x06: Disable SSLv3 in Firefox to protect against POODLE attack

The recent POODLE attack (Padding Oracle On Downgraded Legacy Encryption) exploits a vulnerability of an older version of SSL (SSLv3) by performing a padding oracle attack — and thereby allowing a man-in-the-middle scenario.

To be vulnerable, both client (browser) and server have to support SSLv3. If either one does not support or has disabled the protocol, this vulnerability cannot be exploited. This tiny article shows you how to disable SSLv3 in Firefox — thereby effectively making your browser POODLE-safe.

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  • Aug 04 / 2013
  • 59
Uncategorized

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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