New Software: Modernising the Web Frontend

With today’s post we continue the blog series about our “New Software”.
1. Rewriting the software driving our site
2. Modernising the Web Frontend
3. The Heart of Gold
As outlined in the previous post there were quite a few things to decide upfront, which doesn’t make actual implementation any easier as we will see today when going into more details with the web front end. Beware of the details though as this (and the next part) are going to be much more technical.

Modernising the Web Frontend

With the last post New Software: Rewriting the software driving our site you got a glimpse of why we are rewriting our software. Today we’re going to elaborate a bit more on the front-end part and will provide more in-depth information on the technical changes and news to expect. The main aim of the rewrite is to strengthen the security and to improve maintainability of the source code. On the other hand we aim to avoid showing too much changes to our users.

With choosing Java as the language for the front end we are taking the advantage to develop a modular design based on Object Orientated Programming. This should help to get a better transparency of the source code, which the old PHP source both was lacking. In addition to these basic aspects the use of Java allows for easier packaging of the final application as well as for reworking the code when there is need to do so. This can be aided with several refactoring and code management tools available for Java as the general tooling support is quite good here. One such example is the nice integration of static analysis using tools such as FindBugs to automatically find issues that a static analysis of the code can find, e.g. null-pointer dereferences, misused APIs, thread safety issues, …

As a continuous integration process units test are introduced to test all new features directly while writing the source code. Our tool for this is Jenkins. The unit tests do not only cover the new applied features, the whole source code is tested as well, so that side effects can be discovered in an early stage of the development. Right now there are about 250 test cases running, with many more still to come.

Another important change is the separation from the source logic and the HTML output. While PHP encourages you to intermix HTML templates and executable source, it threatens you to bite you whenever you are not cautious enough. To make it harder to be careless we decided to reduce the power our templates have: The templates are reduced to simply printing values and very easy conditions and loops. An additional safety measure with the template engine is the implicit escaping that is caused for every string that should be printed – if you need to output preprocessed HTML to the template you have to explicitly state so in the template.
The HTML output is based on HTML5 and formatted with CSS3 using LESS to support responsive design patterns and accessibility. Additionally we completely switched to use Unicode, having UTF-8 as our standard encoding.

There is also a change in the URL structure. The new URL concept is based on REST and can easily be scaled to a RESTful API in the future. No more ?id=42 or other meaningless numeric IDs for the various actions.

To avoid SQL injections we opted to use implicit escaping for all data sent to or retrieved from the database; similar to the implicit escaping used with all inputs to the template engine. This way we can process raw data internally and have the necessary conversions and escaping operations whenever the context of the information changes allowing us to concentrate on the actual processing and logic instead of caring about the security implications.

Looking at security we invested some work in reworking the way authentication is handled. While the old system only supported password-based authentication and client certificate login using X.509 there was no chance of combining multiple factors as a requirement for successful login to an account. This lack of multi-factor authentication caused some trouble in the past. To avoid this and to provide more flexibility for our users we want to change the authentication to allow for any combination of login methods, as long as at least one “strong” authentication (like password login, secure token, client certificate) in addition to an optional “multi-factor” authenticator is provided (additional factors may be older TOTPs, single access tokens, ping tokens).

To raise the security level of the password storage we will use with SHA2-256 to store passwords in a save manner. This ensures an attacker can’t easily parallelise brute-forcing or attacking the password hashes as SCrypt guarantees through its design that an attacker needs a certain memory and amount of computational power to calculate the hash value. A switch to SCrypt-SHA2-512 or other even more secure methods later on is already laid out in the source code and can be activated transparently upon next successful password login of the user.

While discussing the authentication of the user let’s take a short break to look at some other security features the new system will implement. As one of the most critical parts with transmitting any information on a secure channel is getting the channel secured we’ll be activating HSTS or also known as HTTP Strict Transport Security. Using HSTS as a baseline we ensure that everyone visiting the site to access sensitive information can benefit of protection from eavesdroppers for future visits. Even if this brings no security on its own – except for mitigating SSL stripping attacks, it sets up the stage for the second mechanism: HPKP. Using Public Key Pinning we not only enforce browsers who had a once good, encrypted channel, to enforce encryption on subsequent visits (as HSTS does), but in addition also tell what valid keys for such a good connection are. Like with HSTS also HPKP suffers the issue of being inline to the connection and thus vulnerable to a determined attacker. With DNS-based Authentication of Named Entities (or for short: DANE) we introduce a second vector for verification a browser can use when determining acceptable security certificates. And even with these mechanisms deployed there is still a lot of room for determining if the connection is secure, some of which will sure follow in a later step.

But apart from ensuring the browser of the user talks to the correct server it is equally important to secure the display of information against mistakes our systems might be doing. One of the options we choose to implement was restricting ourselves using CSP (Content Security Policy) and a separation of our content delivery hosts. Basically to avoid an attacker executing any JavaScript not authorized we split execution of scripts to a subdomain which only carries static script files, while all content that might be under control of the attacker (e.g. the field containing the user name) is delivered on a strictly No-JavaScript subdomain. Thus even XSS was possible it would harden ourselves ill side-effects. To additionally avoid being framed (no pun intended) we will be including various HTTP headers like X-Frame-Options to explicitly prohibit loading within a frame on the attackers website. Also we ask the user’s browser to handle files in the way we specify which, among others, includes disabling of MIME type sniffing. With these security mechanisms in place it raises the bar for an attacker quite a lot and – on the other side – allows us self-testing the application as CSP allows for reporting violations on its rule set. Explicitly triggering such reports can even test the browser and thus determine the protection level the application can expect from the client (e.g. if images which are included for the sole purpose of triggering a report are loaded rather than ignored we know that the client does not properly implement CSP).

Another change will be introduced for the registration of domain names. In the future there are at least 2 ownership checks required to activate a new domain with our system. There will be a choice between the long known email pings, the verification with a DNS-TXT entry, verification with reading HTTP-content from a special addressed file and the verification with CAcert server certificates securely running on internet based services like HTTP, SMTP or XMPP. The way those tests were designed ensures that someone just observing traffic might notice the checks taking place, but won’t gain any information from such observations. All identifiers in these tests are chosen randomly thus simply searching for a particular filename or content of a file with an internet search engine won’t provide you any means to impersonate that domain.

In addition to the checks during the registration of a domain there will be continuous checks to check a domain is still active. If less then two tests succeed the account owner will be informed that there is a verification problem that should be solved within a grace period before all certificates containing that domain will be revoked automatically.

All posts send from the new software will be digitally signed using S/MIME to ensure that these messages are really generated by the CAcert systems and are not SPAM. This has been planned for a long time for the existing code but we did not manage to introduce it there due to complexity and security when realising this function in PHP.

One last but not least interesting feature to be mentioned is the rework of the certificate issuing process in the front end. While in the old software the process was to get all data from the database and check it against the values given in the CSR, this is turned around for the new software: Now first the given CSR is checked and the data gained from the CSR is checked against the records in the database to pre-fill the certificate request form. Changing the way the issuing works we were able to simplify the interface while allowing for new features to come.

After the discussion on why we choose our coding framework and today’s post about the ideas for the new front end the next post will have a closer look at the details of the ideas of the new signer.

CAcert at CeBIT 2015

German version below

On the world’s largest computer fair, the CeBIT in Hannover, DE, CAcert should not be missing out. From March 16th through March 20th Assurers and Assurees are meeting each other at 12:00 CET outside Hall 2 in direction of the green. In case of bad weather the assurances take place directly at the glass front of Hall 2 outside under the roofing.

More details can be found in the Wiki.
CeBIT meeting point

Further events with attendance of CAcert — with a booth at OpenSource events — can be reviewed in the CAcert wiki at

Auf der weltgrößten Computermesse, der CeBIT in Hannover, darf auch CAcert nicht fehlen. Vom 16. bis 20. März treffen sich Assurer und Assurees täglich ab 12 Uhr vor Halle 2 in Richtung der Grünfläche. Bei schlechtem Wetter finden die Assurances direkt an der Glasfront von Halle 2 außen unter der Überdachung statt. Mehr Informationen finden sich im Wiki.

Weitere Veranstaltungen mit CAcert-Beteiligung – mit eigenem Stand auf OpenSource-Veranstaltungen – sind im CAcert-Wiki unter einsehbar.

CAcert auf dem Erlanger Linuxtag 2015

CAcert wird auf dem Erlanger Linuxtag 2015 am 28. Februar 2015 vertreten sein.

Es wird einen Vortrag zu CAcert und die Möglichkeit zur Assurance geben.

Blauen Traube im Turnerbund
Spardorfer Str. 79
91054 Erlangen

New Software: Rewriting the software driving our site

In today’s post we start a blog series about our “New Software”. It will consist of three parts:
1. Rewriting the software driving our site
2. Modernising the Web Frontend
3. The Heart of Gold

As some of the details outlined are still work in progress there’s a chance of things to change, but in general these are things presented to get a grasp of what the software team is being working on for the last year, despite being rather silent otherwise. Feedback to these plans is gladly welcome.

Rewriting the software driving our site

Over the past few months the software team along with other groups like NRE (New Root and Escrow) and Policy Group has been and still is working on rewriting the software that the whole CAcert website is running from scratch. The step was planned for quite some time already, but due to the complexity and the routine work required to keep the current software running it only became possible recently. In this blog post we’d like to describe some of the decisions that were made in this process as some of those decisions are commonly questioned and somewhat controversial.

When we set down to plan the new software one of the main reasons to do so was avoiding the pitfalls we are having with the old software from a maintainability point of view. The old software was written back in 2003 and has ever since only seen patches here and there. If you look closely at the current source you’ll notice about ten different coding styles interleaved into each other. Combined with the quirks of PHP this makes quite a mess that easily gets unmaintainable once you want to implement new features or try to update the software runtime.

Another important aspect when planning the software was redundancy. As the last year has shown you want to mistrust your SSL implementation and every other peace of software you use as much as is practical for your purpose. Yet you still want to protect yourself from those errors if there is a way to do so.

Discussions in the software team meetings were quite heated when the initial thoughts were shared and the basic decisions made. One of those decisions was to drop PHP in the new system due to its quirks and inconsistent API. When surveying other options for a replacement we also took into account that we did not want to have both the front-end and the back-end written in the same language to keep the redundancy we currently have (PHP in the front-end, Perl in the back-end). The list of possible languages contained PHP, Perl, Python, Java, C++, C. Other languages like Groovy, Ruby, Erlang, Haskell and many more were looked at but were discarded due to lack of enough software assessors confident enough to write security-related code with them OR because of weak typing which would reifter heavy discussion we settled for Java in the front-end which was not that undisputed in our team either. Thus when selecting Java we knew of the issues that its runtime has and decided to go along this way for mainly three reasons:

  • Given the number of CVEs it’s not worse then PHP even if many people think it is. When surveying the options we explicitly looked into the security track record and did a count on how many of the issues would have affected us if we restrained our use feature set to some extend. By doing so and leaving out several features like JSPs, JRMI, and many other advanced features we do not need we found it is possible to cut back on attack surface to an acceptable measure.
  • There is really good tooling support for software design, quality control and testing as well as for refactoring. Given the right tools you can prove that before and after a change was made your software still works the same – and all you need to do is writing a few rules saying how you get from A to B.
  • There are lots of people who know the language enough to write code with it that runs without falling over at any occasion – something which needs years of experience with languages like PHP and C++. Comparing these aspects to Python we weren’t as confident about the tooling support and were in addition lacking people in our team who could have done the software reviews. Thus even as we’d love to use something provable like Haskell there’s no point to do so if nobody can assess if a given patch was correct.

A similar situation arose with the signer (currently this part is called CommModule). Although this part basically “works” it’s always a hassle if anything needs to be changed as only few people in our team are confident enough to write Perl. Thus Perl was excluded for the signer too. Instead we settled for C++ for the signer, which might be inintuitive considering the common prejudices regarding the memory management, which, while similar to the broken one from C, has a lot of abstractions actually making live easier. By wrapping the cryptography interfaces of the used library you can keep memory management at a safe distance. Also use of C++ enables us to freely choose among all the (broken) SSL/TLS implementations available; something most other languages would not yield without writing some kind of wrapper.

On the cryptography PoV we discussed several implementations available but ruled one thing quite at the start: We will NOT implement any cryptography ourself on the signer. Thus the cryptography should come from an existing implementation like OpenSSL, LibreSSL, GnuTLS, libNSS, NaCl, CyaSSL/WolffSSL, PolarSSL/embedSSL. As several implementations head differing issues in recent time we decided to keep this part in the new system flexible to switch the implementation without much effort should problems arise. Our favoured backends here were GnuTLS with OpenSSL/LibreSSL as fallbacks – well knowing both have their quite distinct set of issues.

With the question of programming language answered let’s head over to the software design decisions made apart from the mere question of programming language. One aspect in the old system was its inherent lack of any meaningful documentation – something which made the old software basically unfit for any meaningful audit and a hell to maintain. Additionally the old software has a structure which makes writing sensible tests a nightmare (if at all possible). To work around these issues in the new software we plan to maintain documentation inline as part of the code to make updating it along changes to the code as easy as possible. Also most parts of the new software have been covered by a set of unit and integration tests which simplifies the life of our testers: In recent times not only once the test instruction to the old software read “Complete Retest” as there was a lack of integration tests.

Given all these details on the old software and our plans for the future we hope it gives a short introduction to what the software team is working on and why we react quite allergic to people asking when things will be “in their browsers”. It’s not that we are slacking off, but that there is much too much work to do than to communicate every tiny change. If you are interested in some more detail of the new software I’d recommend you reading the follow up parts of this little series which will detail both the features and architecture of the web front-end and will have a closer look at the new signer.

CAcert reaches 300,000 members

[German below]
Last week CAcert reached the milestone of 300,000th community members.
CAcert has honored on behalf for the 300,000 community member Daniel Andris on the ATE Freiburg. Marcus Mängel (Organisation Assurance Officer) on behalf CAcert Inc board presented a paper document as well as an USB crypto stick and a box of Belgian chocolates.

ATE Freiburg 300k
Marcus Mängel (as representative of CAcert board) welcomed Daniel Andris as representative 300,000 community member.

Letzte Woche hat CAcert den Meilenstein von 300.000 Community Mitgliedern überschritten.
CAcert hat stellvertretend für das 300.000 Community Mitglied Daniel Andris auf dem ATE Freiburg geehrt. Neben einer Urkunde überreichte Marcus Mängel (Organisation Assurance Officer) im Auftrag des CAcert Inc Boards einen USB-Crypto-Stick und eine Schachtel belgische Pralinen.

CAcert root certificates included in the Replicant (Android) distribution

The Android distribution Replicant has recently decided to include the CAcert root certificates in default installations.

Replicant logo

Replicant was started as a pragmatic way to achieve software freedom on mobile devices, providing a fully free version of Android. Over the years, support for a dozen of different mainstream devices was added.
However, most of these devices are severely flawed when it comes to software freedom, privacy and security. Thus, it was decided to focus the development effort of Replicant for a few specific devices that perform better regarding those aspects, instead of trying to catch up with the latest mainstream devices. Replicant is sponsored and supported by the Free Software Foundation.

For further details on the inclusion status of CAcert’s root certificates in other OS distributions see

Assurance Party in Dresden am 10. Februar 2015

Im Hackerspace in Dresden findet am 10. Februar 2015 ab 19:00 eine CAcert Assurer Party statt.
Dies ist sicherlich eine gute Gelegenheit für alle Interessierten aus dem Raum Dresden assured zu werden und das CAcert Web of Trust enger zu weben.

Näheres findet sich auf der Webseite des C3D2.

Next language translated to 100%

Special thanks to alaks who made Czech the sixth language which is now available with a 100% translation rate. In addition I want to thank all translators who did a tremendous work over the past years.

To show how far the various languages have been translated here a short statistic overview covering languages with more than 30% of progress

Language Progress
Spanish 100%
German 100%
French 100%
Italian 100%
Dutch 100%
Czech 100%
Portuguese (Brazil) 83%
Swedish 64%
Hungarian 43%
Finnish 37%
Japanese 36%

It would be great if even more people could be helping to translate the software. We are especially looking for Portuguese (Brazil), Swedish, Hungarian, Finnish, Japanese. Of course any help for the other languages that CAcert is offering is appreciated.

If you want to help just create an account on CAcert’s translation server

For more information look at
or join the translation mailing list

Thanks to all who already helped with the translation!

ATE Freiburg, 2015-02-02

Freiburg i. Breisgau panorama
Am Montag, 2. Februar 2015 findet in den Räumen des Karma Indian Palace in Freiburg das nächste ATE in Deutschland statt.

  • Was hast du auf dem CAP Formular hinzuzufügen, wenn du Minderjährige überprüfst ?
  • Warum solltest du dir die 3 Buchstaben: R/L/O einprägen ?
  • Wie verhälst du dich, wenn du ein fremdes Ausweis-Dokument zum ersten mal prüfst ?

Antworten auf diese und andere Fragen erhaltet ihr auf dem Assurer Training Event.
Bringt geeignete Lichtbildausweise für Assurances mit.

ATE-Freiburg findet statt:

Karma Indian Palace
Starts: 2015-02-02 19:00
Duration: 3 hours:
Bertoldstrasse 51-53
Freiburg, Baden-Wuertemburg

Registrierung: Ich moechte am ATE-Freiburg teilnehmen

Vielleicht treffen wir uns ja da.

Mit bestem Gruß vom Events Team!

Weitere Infos:
ATE Freiburg im CAcert Wiki

CAcert at FOSDEM 2015, Jan 31st – Feb 1st

FOSDEM, the Free and Open Source Software Developers

CAcert and secure-u e.V. will be present at FOSDEM 2015, the Free and Open Source Software Developers’ European Meeting, on January 31st – February 1st.

If you want to help at our booth, register yourself on our events wiki page for FOSDEM 2015 planning.