VoIP security architecture in brief

Voice over IP (VoIP) has been around for a long time. It’s ubiquitous in homes, data centers and carrier networks. Despite this ubiquity, security is rarely a priority. With the combination of a handful of important standard protocols, it is possible to make untappable end to end encryption for an established VoIP call. TLS is the security protocol between the signaling endpoints of the session. It’s the same technology that exists for SSL web sites; ecommerce, secure webmail, Tor and many others use TLS for security. [Read More]
ostel  ostn  sip  tls  voip  zrtp 

Threats and Usability of Secure Voice

In my previous post I found that end-to-end encryption with OSTN is both effective and usable. There are two important things the user must be aware of when using OSTN. They must confirm with each phone call that the encryption icon is present and they must correctly complete SAS verification dialog boxes. So on a basic level, encrypted voice just works. But, what does this all mean? This post looks at the threats to security and usability of encrypted ZRTP phone calls in CSipSimple. [Read More]

A Network Analysis of Encrypted Voice over OSTN

Introduction to OSTN The OSTN network stands for Open Source Telephony Network. It is a federated network standard for supporting Internet calling with end-to-end encryption ala ZRTP. Its very similar to e-mail in that VOIP calls can be routed to addresses such as user@domain.tld. Its a simple concept, but I believe it to be ground breaking implementation! Never before have I seen such an accessible solution to encrypted VOIP calls. OSTN is platform independent, is a federated network, and it is an open standard such that it is widely adoptable. [Read More]

<!--:en-->OSTN secure VoIP wizard now built into CSipSimple for Android<!--:-->

If you saw our last post about how to setup your own secure voice-over-IP server instance, then this news is for you. If you are an Android user looking for the best open-source VoIP app, and really need one that can support secure communications, then this post is ALSO for you. CSipSimple, the previously mentioned “best VoIP app”, now includes a wizard for setting up an account configuration for any server which complies with our Open Secure Telephony Network specification. [Read More]
ostel  ostn  sip  voip  zrtp 

<!--:en-->Build your own Open Secure Telephony Network, some assembly required<!--:-->

The Open Secure Telephony Network is a standard that defines how to configure a VoIP softswitch with the capability to have secure two-way VoIP conversations if both parties are using the same server. The system requires both backend and frontend components, which makes OSTN is a little different than some of the other Guardian apps. Unlike Gibberbot, there are few public SIP services that support secure signalling for a mobile app to connect with. [Read More]

Singing and Dancing for Encryption

If you see me dancing or signing with my phone in my hand, I may not just be having a great time, but also creating an encryption key. Part of the issue with security is that it can often be difficult to implement or an added step in what users want to be an easy and seamless process. What if we can make secure and private communications fun and easy? [Read More]

Call My Email

What if you could call me directly through my email? No exchanging of phone numbers or searching for handles on Skype. Just plain and simple email. Now what if we can make that phone call as secure as it is easy. That’s the goal of what we’re doing here at Open Secure Telephony Network (OSTN). The internet is already structured to be able to do this. That’s why I can have all of my emails point to one email box if I want to. [Read More]

Acrobits Groundwire – OSTN supports iPhone

The Guardian Project develops open source software primarily for the Android platform but we strive for security by design to be a part of all platforms. With OSTN, there are two major components. The the first is the server, which operates as the primary user directory and call switch. The other is the client, which is the program you interact with to send and receive calls. While the Apple App Store forbids distribution of GPL licensed software from their service, the underlying protocols used by OSTN are open, so even iPhone developers may implement them in a proprietary client application without breaking any intellectual property laws. [Read More]
iphone  ostn  sip  voip  zrtp 

Free SIP Providers with ZRTP support

This post is part of a series on our work researching the Open Secure Telephony Network. After you have CSipSimple installed on your mobile handset, you will need a place to register a SIP username so you can contact others. The fastest way to get started with this is to use one of a handful of free SIP providers. I like the Ekiga free SIP service. The only drawback to this service is the userbase is large enough that the namespace of easy to remember words is frequently occupied. [Read More]
ostn  secure  voip  zrtp 

Open Source SIP Client for Android

The first step in the Open Secure Telephony Network (OSTN) is a client. We can’t make a phone call without a phone. In this case there are three primary goals and a number of optional features. The primary goal is an application which speaks the SIP protocol for signalling. It must also speak the ZRTP protocol for peer to peer encryption key exchange. Finally the client must have source code freely available with a license that allows free redistribution. [Read More]
ostn  voip  zrtp 

Open Secure Telephony Network

Over the last two months, I have been working on a project to research and develop a set of tools to provide secure peer to peer Voice over IP on the Android mobile platform. It is called the Open Secure Telephony Network, or OSTN. This work is done under the umbrella of The Guardian Project. this is not the type of “open” we mean, and definitely not secure The project will continue for another four months and I will post my public findings here. [Read More]
ostn  voip  zrtp