The Freedom Phone advertises itself as a "Free speech and privacy first focused phone". As documented on the features page, it runs ClearOS, an Android-based OS produced by Clear United (or maybe one of the bewildering array of associated companies, we'll come back to that later). It's advertised as including Signal, but what's shipped is not the version available from the Signal website or any official app store - instead it's this fork called "ClearSignal".

The first thing to note about ClearSignal is that the privacy policy link from that page 404s, which is not a great start. The second thing is that it has a version number of 5.8.14, which is strange because upstream went from 5.8.10 to 5.9.0. The third is that, despite Signal being GPL 3, there's no source code available. So, I grabbed jadx and started looking for differences between ClearSignal and the upstream 5.8.10 release. The results were, uh, surprising.

First up is that they seem to have integrated ACRA, a crash reporting framework. This feels a little odd - in the absence of a privacy policy, it's unclear what information this gathers or how it'll be stored. Having a piece of privacy software automatically uploading information about what you were doing in the event of a crash with no notification other than a toast that appears saying "Crash Report" feels a little dubious.

Next is that Signal (for fairly obvious reasons) warns you if your version is out of date and eventually refuses to work unless you upgrade. ClearSignal has dealt with this problem by, uh, simply removing that code. The MacOS version of the desktop app they provide for download seems to be derived from a release from last September, which for an Electron-based app feels like a pretty terrible idea. Weirdly, for Windows they link to an official binary release from February 2021, and for Linux they tell you how to use the upstream repo properly. I have no idea what's going on here.

They've also added support for network backups of your Signal data. This involves the backups being pushed to an S3 bucket using credentials that are statically available in the app. It's ok, though, each upload has some sort of nominally unique identifier associated with it, so it's not trivial to just download other people's backups. But, uh, where does this identifier come from? It turns out that Clear Center, another of the Clear family of companies, employs a bunch of people to work on a ClearID[1], some sort of decentralised something or other that seems to be based on KERI. There's an overview slide deck here which didn't really answer any of my questions and as far as I can tell this is entirely lacking any sort of peer review, but hey it's only the one thing that stops anyone on the internet being able to grab your Signal backups so how important can it be.

The final thing, though? They've extended Signal's invitation support to encourage users to get others to sign up for Clear United. There's an exposed API endpoint called "get_user_email_by_mobile_number" which does exactly what you'd expect - if you give it a registered phone number, it gives you back the associated email address. This requires no authentication. But it gets better! The API to generate a referral link to send to others sends the name and phone number of everyone in your phone's contact list. There does not appear to be any indication that this is going to happen.

So, from a privacy perspective, going to go with things being some distance from ideal. But what's going on with all these Clear companies anyway? They all seem to be related to Michael Proper, who founded the Clear Foundation in 2009. They are, perhaps unsurprisingly, heavily invested in blockchain stuff, while Clear United also appears to be some sort of multi-level marketing scheme which has a membership agreement that includes the somewhat astonishing claim that:

Specifically, the initial focus of the Association will provide members with supplements and technologies for:

9a. Frequency Evaluation, Scans, Reports;

9b. Remote Frequency Health Tuning through Quantum Entanglement;

9c. General and Customized Frequency Optimizations;

- there's more discussion of this and other weirdness here. Clear Center, meanwhile, has a Chief Physics Officer? I have a lot of questions.

Anyway. We have a company that seems to be combining blockchain and MLM, has some opinions about Quantum Entanglement, bases the security of its platform on a set of novel cryptographic primitives that seem to have had no external review, has implemented an API that just hands out personal information without any authentication and an app that appears more than happy to upload all your contact details without telling you first, has failed to update this app to keep up with upstream security updates, and is violating the upstream license. If this is their idea of "privacy first", I really hate to think what their code looks like when privacy comes further down the list.

[1] Pointed out to me here

comments

Inspired by the recent news of AV1 hardware encoding support from Intel, I decided to look into the state of AV1 on Linux today. AV1 is a free and open standard as defined by Digistan without any royalty payment requirement, unlike its much used competitor encoding H.264. While looking, I came across an 5 year old question on askubuntu.com which in turn inspired me to check out how things are in Debian Stable regarding AV1. The test file listed in the question (askubuntu_test_aom.mp4) did not exist any more, so I tracked down a different set of test files on av1.webmfiles.org to test them with the various video tools I had installed on my machine. I was happy to discover that AV1 decoding and playback worked with almost every tool I tested:

mediainfo	ok
dragonplayer	ok
ffmpeg / ffplay	ok
gnome-mplayer	fail
mplayer	ok
mpv	ok
parole	ok
vlc	ok
firefox	ok
chromium	ok

AV1 encoding is available in Debian Stable from the aom-tools version 1.0.0.errata1-3 package, using the aomenc tool. The encoding using the package in Debian Stable is quite slow, with the frame rate for my 10 second test video at around 0.25 fps. My 10 second video test took 16 minutes and 11 seconds on my test machine. I tested by first running ffmpeg and then aomenc using the recipe provided by the askubuntu recipe above. I had to remove the '--row-mt=1' option, as it was not supported in my 1.0.0 version. The encoding only used a single thread, according to top.

ffmpeg -i some-old-video.ogv -t 10 -pix_fmt yuv420p video.y4m
aomenc --fps=24/1 -u 0 --codec=av1 --target-bitrate=1000 \
  --lag-in-frames=25 --auto-alt-ref=1 -t 24 --cpu-used=8 \
  --tile-columns=2 --tile-rows=2 -o output.webm video.y4m

As version 1.0.0 currently have several unsolved security issues in Debian Stable, and to see if the recent backport provided in Debian is any quicker, I ran apt -t bullseye-backports install aom-tools to fetch the backported version and re-encoded the video using the latest version. This time the '--row-mt=1' option worked, and the encoding was done in 46 seconds with a frame rate of around 5.22 fps. This time it seem to be using all my four cores to encode. Encoding speed is still too low for streaming and real time, which would require frame rates above 25 fps, but might be good enough for offline encoding. I am very happy to see AV1 playback working so well with the default tools in Debian Stable. I hope the encoding situation improve too, allowing even a slow old computer like my 10 year old laptop to be used for encoding. As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

The Reproducible Builds project relies on several projects, supporters and sponsors for financial support, but they are also valued as ambassadors who spread the word about the project and the work that we do. This is the third instalment in a series featuring the projects, companies and individuals who support the Reproducible Builds project. If you are a supporter of the Reproducible Builds project (of whatever size) and would like to be featured here, please let get in touch with us at contact@reproducible-builds.org. We started this series by featuring the Civil Infrastructure Platform project and followed this up with a post about the Ford Foundation. Today, however, we ll be talking with Dan Romanchik, Communications Manager at Amateur Radio Digital Communications (ARDC).
Chris Lamb: Hey Dan, it s nice to meet you! So, for someone who has not heard of Amateur Radio Digital Communications (ARDC) before, could you tell us what your foundation is about? Dan: Sure! ARDC s mission is to support, promote, and enhance experimentation, education, development, open access, and innovation in amateur radio, digital communication, and information and communication science and technology. We fulfill that mission in two ways:

1. We administer an allocation of IP addresses that we call 44Net. These IP addresses (in the 44.0.0.0/8 IP range) can only be used for amateur radio applications and experimentation.
2. We make grants to organizations whose work aligns with our mission. This includes amateur radio clubs as well as other amateur radio-related organizations and activities. Additionally, we support scholarship programs for people who either have an amateur radio license or are pursuing careers in technology, STEM education and open-source software development projects that fit our mission, such as Reproducible Builds.

Chris: How might you relate the importance of amateur radio and similar technologies to someone who is non-technical? Dan: Amateur radio is important in a number of ways. First of all, amateur radio is a public service. In fact, the legal name for amateur radio is the Amateur Radio Service, and one of the primary reasons that amateur radio exists is to provide emergency and public service communications. All over the world, amateur radio operators are prepared to step up and provide emergency communications when disaster strikes or to provide communications for events such as marathons or bicycle tours. Second, amateur radio is important because it helps advance the state of the art. By experimenting with different circuits and communications techniques, amateurs have made significant contributions to communications science and technology. Third, amateur radio plays a big part in technical education. It enables students to experiment with wireless technologies and electronics in ways that aren t possible without a license. Amateur radio has historically been a gateway for young people interested in pursuing a career in engineering or science, such as network or electrical engineering. Fourth and this point is a little less obvious than the first three amateur radio is a way to enhance international goodwill and community. Radio knows no boundaries, of course, and amateurs are therefore ambassadors for their country, reaching out to all around the world. Beyond amateur radio, ARDC also supports and promotes research and innovation in the broader field of digital communication and information and communication science and technology. Information and communication technology plays a big part in our lives, be it for business, education, or personal communications. For example, think of the impact that cell phones have had on our culture. The challenge is that much of this work is proprietary and owned by large corporations. By focusing on open source work in this area, we help open the door to innovation outside of the corporate landscape, which is important to overall technological resiliency.
Chris: Could you briefly outline the history of ARDC? Dan: Nearly forty years ago, a group of visionary hams saw the future possibilities of what was to become the internet and requested an address allocation from the Internet Assigned Numbers Authority (IANA). That allocation included more than sixteen million IPv4 addresses, 44.0.0.0 through 44.255.255.255. These addresses have been used exclusively for amateur radio applications and experimentation with digital communications techniques ever since. In 2011, the informal group of hams administering these addresses incorporated as a nonprofit corporation, Amateur Radio Digital Communications (ARDC). ARDC is recognized by IANA, ARIN and the other Internet Registries as the sole owner of these addresses, which are also known as AMPRNet or 44Net. Over the years, ARDC has assigned addresses to thousands of hams on a long-term loan (essentially acting as a zero-cost lease), allowing them to experiment with digital communications technology. Using these IP addresses, hams have carried out some very interesting and worthwhile research projects and developed practical applications, including TCP/IP connectivity via radio links, digital voice, telemetry and repeater linking. Even so, the amateur radio community never used much more than half the available addresses, and today, less than one third of the address space is assigned and in use. This is one of the reasons that ARDC, in 2019, decided to sell one quarter of the address space (or approximately 4 million IP addresses) and establish an endowment with the proceeds. This endowment now funds ARDC s a suite of grants, including scholarships, research projects, and of course amateur radio projects. Initially, ARDC was restricted to awarding grants to organizations in the United States, but is now able to provide funds to organizations around the world.
Chris: How does the Reproducible Builds effort help ARDC achieve its goals? Dan: Our aspirational goals include:

• Broad reach. We look for projects that will benefit the widest community possible.
• Social over commercial benefit. We prioritize giving to organizations and funding projects that may not have a viable business model, but provide a clear benefit to society.
• Preservation of the right to innovate. We oppose any efforts that restrict innovation to protect the status quo and keep the current winners in privileged positions.

We think that the Reproducible Builds efforts in helping to ensure the safety and security of open source software closely align with those goals.
Chris: Are there any specific success stories that ARDC is particularly proud of? Dan: We are really proud of our grant to the Hoopa Valley Tribe in California. With a population of nearly 2,100, their reservation is the largest in California. Like everywhere else, the COVID-19 pandemic hit the reservation hard, and the lack of broadband internet access meant that 130 children on the reservation were unable to attend school remotely. The ARDC grant allowed the tribe to address the immediate broadband needs in the Hoopa Valley, as well as encourage the use of amateur radio and other two-way communications on the reservation. The first nation was able to deploy a network that provides broadband access to approximately 90% of the residents in the valley. And, in addition to bringing remote education to those 130 children, the Hoopa now use the network for remote medical monitoring and consultation, adult education, and other applications. Other successes include our grants to:

• The ARRL Foundation, which has awarded dozens of scholarships over the past couple of years to amateur radio operators both young and old.

• The Chippewa Valley Amateur Club, who used the grant to build an emergency communications trailer and improve the emergency communication infrastructure in their community.
• Woodridge Middle School, who have developed innovative, hands-on, radio-related projects that have dramatically increased the test scores of the kids in their STEM program.
• The Make Operating Radio Easier (MORE) Project, which aims to reduce both gender and age imbalances in ham radio, through education and hands-on activities. Led by the IEEE Central Jersey Section, MORE provides mentoring, proactive intervention, and inclusivity to groups that are under-represented in amateur radio.

Chris: ARDC supports a number of other existing projects and initiatives, not all of them in the open source world. How much do you feel being a part of the broader free culture movement helps you achieve your aims? Dan: In general, we find it challenging that most digital communications technology is proprietary and closed-source. It s part of our mission to fund open source alternatives. Without them, we are solely reliant, as a society, on corporate interests for our digital communication needs. It makes us vulnerable and it puts us at risk of increased surveillance. Thus, ARDC supports open source software wherever possible, and our grantees must make a commitment to share their work under an open source license or otherwise make it as freely available as possible.
Chris: Thanks so much for taking the time to talk to us today. Now, if someone wanted to know more about ARDC or to get involved, where might they go to look? To learn more about ARDC in general, please visit our website at https://www.ampr.org. To learn more about 44Net, go to https://wiki.ampr.org/wiki/Main_Page. And, finally, to learn more about our grants program, go to https://www.ampr.org/apply/

---

For more about the Reproducible Builds project, please see our website at reproducible-builds.org. If you are interested in ensuring the ongoing security of the software that underpins our civilisation and wish to sponsor the Reproducible Builds project, please reach out to the project by emailing contact@reproducible-builds.org.

A new minor release of drat arrived on CRAN today. drat stands for drat R Archive Template, and helps with easy-to-create and easy-to-use repositories for R packages. Since its inception in early 2015 it has found widespread adoption among R users because repositories with marked releases is the better way to distribute code. See below for a few custom reference examples. Because for once it really is as your mother told you: Friends don t let friends install random git commit snapshots. Properly rolled-up releases it is. Just how CRAN shows us: a model that has demonstrated for two-plus decades how to do this. And you can too: drat is easy to use, documented by six vignettes and just works. Detailed information about drat is at its documentation site. This release adds support for the macOS Arm M1 architecture, initially supplied in a PR last fall and now finalized with additional tests. The NEWS file summarises the release as follows:

Changes in drat version 0.2.3 (2022-04-13)

• Arm M1 repos are now supported (#126 and #131 fixing #125)
• A vignette typo has been fixed (#130)

Courtesy of my CRANberries, there is a comparison to the previous release. More detailed information is on the drat page as well as at the documentation site. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

After listening to an episode of the 2.5 admins podcast, I realized there was some sort of low-hanging fruit I could pick to better tune my WiFi at home. You see, I'm kind of a fraud in WiFi: I only started a WiFi mesh in Montreal (now defunct), I don't really know how any of that stuff works. So I was surprised to hear one of the podcast host say "it's all about airtime" and "you want to reduce the power on your access points" (APs). It seemed like sound advice: better bandwidth means less time on air, means less collisions, less latency, and less power also means less collisions. Worth a try, right?

Frequency So the first thing I looked at was WifiAnalyzer to see if I had any optimisation I could do there. Normally, I try to avoid having nearby APs on the same frequency to avoid collisions, but who knows, maybe I had messed that up. And turns out I did! Both APs were on "auto" for 5GHz, which typically means "do nothing or worse". 5GHz is really interesting, because, in theory, there are LOTS of channels to pick from, it goes up to 196!! And both my APs were on 36, what gives? So the first thing I did was to set it to channel 100, as there was that long gap in WifiAnalyzer where no other AP was. But that just broke 5GHz on the AP. The OpenWRT GUI (luci) would just say "wireless not associated" and the ESSID wouldn't show up in a scan anymore. At first, I thought this was a problem with OpenWRT or my hardware, but I could reproduce the problem with both my APs: a TP-Link Archer A7 v5 and a Turris Omnia (see also my review). As it turns out, that's because that range of the WiFi band interferes with trivial things like satellites and radar, which make the actually very useful radar maps look like useless christmas trees. So those channels require DFS to operate. DFS works by first listening on the frequency for a certain amount of time (1-2 minute, but could be as high as 10) to see if there's something else transmitting at all. So typically, that means they just don't operate at all in those bands, especially if you're near any major city which generally means you are near a weather radar that will transmit on that band. In the system logs, if you have such a problem, you might see this:

Apr  9 22:17:39 octavia hostapd: wlan0: DFS-CAC-START freq=5500 chan=100 sec_chan=1, width=0, seg0=102, seg1=0, cac_time=60s
Apr  9 22:17:39 octavia hostapd: DFS start_dfs_cac() failed, -1

... and/or this:

Sat Apr  9 18:05:03 2022 daemon.notice hostapd: Channel 100 (primary) not allowed for AP mode, flags: 0x10095b NO-IR RADAR
Sat Apr  9 18:05:03 2022 daemon.warn hostapd: wlan0: IEEE 802.11 Configured channel (100) not found from the channel list of current mode (2) IEEE 802.11a
Sat Apr  9 18:05:03 2022 daemon.warn hostapd: wlan0: IEEE 802.11 Hardware does not support configured channel

Here, it clearly says RADAR (in all caps too, which means it's really important). NO-IR is also important, I'm not sure what it means but it could be that you're not allowed to transmit in that band because of other local regulations. There might be a way to workaround those by changing the "region" in the Luci GUI, but I didn't mess with that, because I figured that other devices will have that already configured. So using a forbidden channel might make it more difficult for clients to connect (although it's possible this is enforced only on the AP side). In any case, 5GHz is promising, but in reality, you only get from channel 36 (5.170GHz) to 48 (5.250GHz), inclusively. Fast counters will notice that is exactly 80MHz, which means that if an AP is configured for that hungry, all-powerful 80MHz, it will effectively take up all 5GHz channels at once. This, in other words, is as bad as 2.4GHz, where you also have only two 40MHz channels. (Really, what did you expect: this is an unregulated frequency controlled by commercial interests...) So the first thing I did was to switch to 40MHz. This gives me two distinct channels in 5GHz at no noticeable bandwidth cost. (In fact, I couldn't find hard data on what the bandwidth ends up being on those frequencies, but I could still get 400Mbps which is fine for my use case.)

Power The next thing I did was to fiddle with power. By default, both radios were configured to transmit as much power as they needed to reach clients, which means that if a client gets farther away, it would boost its transmit power which, in turns, would mean the client would still connect to instead of failing and properly roaming to the other AP. The higher power also means more interference with neighbors and other APs, although that matters less if they are on different channels. On 5GHz, power was about 20dBm (100 mW) -- and more on the Turris! -- when I first looked, so I tried to lower it drastically to 5dBm (3mW) just for kicks. That didn't work so well, so I bumped it back up to 14 dBm (25 mW) and that seems to work well: clients hit about -80dBm when they get far enough from the AP, which gets close to the noise floor (and where the neighbor APs are), which is exactly what I want. On 2.4GHz, I lowered it down even further, to 10 dBm (10mW) since it's better at going through wells, I figured it would need less power. And anyways, I rather people use the 5GHz APs, so maybe that will act as an encouragement to switch. I was still able to connect correctly to the APs at that power as well.

Other tweaks I disabled the "Allow legacy 802.11b rates" setting in the 5GHz configuration. According to this discussion:

Checking the "Allow b rates" affects what the AP will transmit. In particular it will send most overhead packets including beacons, probe responses, and authentication / authorization as the slow, noisy, 1 Mb DSSS signal. That is bad for you and your neighbors. Do not check that box. The default really should be unchecked.

This, in particular, "will make the AP unusable to distant clients, which again is a good thing for public wifi in general". So I just unchecked that box and I feel happier now. I didn't make tests to see the effect separately however, so this is mostly just a guess.

A month after the major release 0.2.0 bringing pub/sub and other goodies to our RcppRedis package, a new version 0.2.1 arrived on CRAN yesterday. RcppRedis is one of several packages connecting R to the fabulous Redis in-memory datastructure store (and much more). RcppRedis does not pretend to be feature complete, but it may do some things faster than the other interfaces, and also offers an optional coupling with MessagePack binary (de)serialization via RcppMsgPack. The package has carried production loads for several years now. This release updated the rredis suggestion by adding an Additional_repositories entry as Bryan decided to retire the rredis package. You can still install it via install.packages("rredis") by setting the addtional repo, for example repos=c("https://ghrr.github.io/drat", getOption("repos")) as documented in package and at our ghrr drat repo. The detailed changes list follows.

Changes in version 0.2.1 (2022-04-09)

• The rredis package can be installed via the repo listed in Additional_repositories; the pubsub.R test file makes rredis optional and conditional; all demos now note that the optional rredis package is installable via the drat listed in Additional_repositories.
• The fallback-compilation of hiredis has been forced to override compilation flags because CRAN knows better than upstream.
• The GLOBEX pub/sub example has small updates.

Courtesy of CRANberries, there is also a diffstat report for this release. More information is on the RcppRedis page. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

A new release 0.3.3.9.2 of RcppEigen arrived on CRAN today (and already went to Debian). Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms. This update was (as it happens) requested by CRAN as R aims to bring the Fortran / C interface to best practices. We call dgesdd twice in one example and use a character argument, and the-powers-that-be now prefer better control over that character argument. So we did. Another change, kindly contributed by Mikael Jagan, switches row and column indices for R_xlen_t allowing for greater range. Plus some more small tweaks mostly to CI, see the NEWS entry below for full details. And again as we said for the previous three releases:

One additional and recent change was the accomodation of a recent CRAN Policy change to not allow gcc or clang to mess with diagnostic messages. A word of caution: this may make your compilation of packages using RcppEigen very noisy so consider adding -Wno-ignored-attributes to the compiler flags added in your ~/.R/Makevars.

We still find this requirement rather annoying. Eigen is only usable if you set, say,

-Wno-deprecated-declarations -Wno-parentheses -Wno-ignored-attributes -Wno-unused-function

asoptions in~/.R/Makevars . But CRAN makes the rules. Maybe if a few of us gently and politely nudge them they may relent one day. One can only hope. The complete NEWS file entry follows.

Changes in RcppEigen version 0.3.3.9.2 (2022-04-05)

• Added test coverage in continuous integration
• Added new tests to increase test coverage
• Small improvement to the RcppEigen.package.skeleton() code
• Small updates and edits to README.md and inst/CITATION
• Use R_xlen_t for vector rows and columns (by Mikael Jagan)
• Support USE_FC_LEN_T by adding FCONE to two dgesdd calls

Courtesy of CRANberries, there is also a diffstat report for the most recent release. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Welcome to the March 2022 report from the Reproducible Builds project! In our monthly reports we outline the most important things that we have been up to over the past month.
The in-toto project was accepted as an incubating project within the Cloud Native Computing Foundation (CNCF). in-toto is a framework that protects the software supply chain by collecting and verifying relevant data. It does so by enabling libraries to collect information about software supply chain actions and then allowing software users and/or project managers to publish policies about software supply chain practices that can be verified before deploying or installing software. CNCF foundations hosts a number of critical components of the global technology infrastructure under the auspices of the Linux Foundation. (View full announcement.)
Herv Boutemy posted to our mailing list with an announcement that the Java Reproducible Central has hit the milestone of 500 fully reproduced builds of upstream projects . Indeed, at the time of writing, according to the nightly rebuild results, 530 releases were found to be fully reproducible, with 100% reproducible artifacts.
GitBOM is relatively new project to enable build tools trace every source file that is incorporated into build artifacts. As an experiment and/or proof-of-concept, the GitBOM developers are rebuilding Debian to generate side-channel build metadata for versions of Debian that have already been released. This only works because Debian is (partial) reproducible, so one can be sure that that, if the case where build artifacts are identical, any metadata generated during these instrumented builds applies to the binaries that were built and released in the past. More information on their approach is available in README file in the bomsh repository.
Ludovic Courtes has published an academic paper discussing how the performance requirements of high-performance computing are not (as usually assumed) at odds with reproducible builds. The received wisdom is that vendor-specific libraries and platform-specific CPU extensions have resulted in a culture of local recompilation to ensure the best performance, rendering the property of reproducibility unobtainable or even meaningless. In his paper, Ludovic explains how Guix has:

[ ] implemented what we call package multi-versioning for C/C++ software that lacks function multi-versioning and run-time dispatch [ ]. It is another way to ensure that users do not have to trade reproducibility for performance. (full PDF)

Kit Martin posted to the FOSSA blog a post titled The Three Pillars of Reproducible Builds. Inspired by the shock of infiltrated or intentionally broken NPM packages, supply chain attacks, long-unnoticed backdoors , the post goes on to outline the high-level steps that lead to a reproducible build:

It is one thing to talk about reproducible builds and how they strengthen software supply chain security, but it s quite another to effectively configure a reproducible build. Concrete steps for specific languages are a far larger topic than can be covered in a single blog post, but today we ll be talking about some guiding principles when designing reproducible builds. [ ]

The article was discussed on Hacker News.
Finally, Bernhard M. Wiedemann noticed that the GNU Helloworld project varies depending on whether it is being built during a full moon! (Reddit announcement, openSUSE bug report)

Events There will be an in-person Debian Reunion in Hamburg, Germany later this year, taking place from 23 30 May. Although this is a Debian event, there will be some folks from the broader Reproducible Builds community and, of course, everyone is welcome. Please see the event page on the Debian wiki for more information. Bernhard M. Wiedemann posted to our mailing list about a meetup for Reproducible Builds folks at the openSUSE conference in Nuremberg, Germany. It was also recently announced that DebConf22 will take place this year as an in-person conference in Prizren, Kosovo. The pre-conference meeting (or Debcamp ) will take place from 10 16 July, and the main talks, workshops, etc. will take place from 17 24 July.

Misc news Holger Levsen updated the Reproducible Builds website to improve the documentation for the SOURCE_DATE_EPOCH environment variable, both by expanding parts of the existing text [ ][ ] as well as clarifying meaning by removing text in other places [ ]. In addition, Chris Lamb added a Twitter Card to our website s metadata too [ ][ ][ ]. On our mailing list this month:

• Early in the month, Mattia Rizzolo posted to our mailing list asking for early thoughts about running an in-person Reproducible Builds event later in 2022.
• Chris Lamb then posted to our mailing list with a call for real-world instances where reproducibility practices have flagged something legitimately bad . Although no public, concrete examples were cited, the resulting discussion was interesting and wide-ranging.
• Marc Haber also posted to our mailing list with an interesting problem where building Debian packages with libfaketime yields different results when run outside of libfaketime.

Distribution work In Debian this month:

• Johannes Schauer Marin Rodrigues posted to the debian-devel list mentioning that he exploited the property of reproducibility within Debian to demonstrate that automatically converting a large number of packages to a new internal source version did not change the resulting packages. The proposed change could therefore be applied without causing breakage:

So now we have 364 source packages for which we have a patch and for which we can show that this patch does not change the build output. Do you agree that with those two properties, the advantages of the 3.0 (quilt) format are sufficient such that the change shall be implemented at least for those 364? [ ]

• 144 reviews of Debian packages were added, 241 were updated and 20 were removed this month, significantly adding to our knowledge about identified issues. A number of issue types were updated too, including buildpath_in_postgres_opcodes, captures_kernel_version_via_CMAKE_SYSTEM, build_id_differences_only, etc.
• Lukas Puehringer updated both the python-securesystemslib package to version 0.22.0-1 and the in-toto package to 1.2.0-1.

In openSUSE, Bernhard M. Wiedemann posted his usual monthly reproducible builds status report.

Tooling diffoscope is our in-depth and content-aware diff utility. Not only can it locate and diagnose reproducibility issues, it can provide human-readable diffs from many kinds of binary formats. This month, Chris Lamb prepared and uploaded versions 207, 208 and 209 to Debian unstable, as well as made the following changes to the code itself:

• Update minimum version of Black to prevent test failure on Ubuntu jammy. [ ]
• Updated the R test fixture for the 4.2.x series of the R programming language. [ ]

Brent Spillner also worked on adding graceful handling for UNIX sockets and named pipes to diffoscope. [ ][ ][ ]. Vagrant Cascadian also updated the diffoscope package in GNU Guix. [ ][ ] reprotest is the Reproducible Build s project end-user tool to build the same source code twice in widely different environments and checking whether the binaries produced by the builds have any differences. This month, Santiago Ruano Rinc n added a new --append-build-command option [ ], which was subsequently uploaded to Debian unstable by Holger Levsen.

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

• Bernhard M. Wiedemann:
  • epub2txt2 (filesystem-related issue)
  • fdupes (toolchain issue)
  • grep (ASLR-related issue)
  • hello (PGO-related issue)
  • osdlyrics (date-related regression regression)
  • texlive (GZip modification time issue)
  • tuigreet (ordering issue)
• Huong Nguyenthi:
  • #1006646 filed against sgml-base.
• Chris Lamb:
  • #1007232 filed against python-ara.
  • #1007757 filed against nbformat.
  • #1007760 filed against chemical-structures.
  • #1007908 filed against fiat.
• Vagrant Cascadian:
  • #1006844 filed against intel-mediasdk.
  • #1006858 filed against libao.
  • #1006860 & #1006861 filed against pcp.
  • #1006863 filed against tevent.
  • #1006864 filed against pcp.
  • #1006865 filed against apr-util.
  • #1006979 filed against liggghts.
  • #1007094 filed against kristall.
  • #1007095 filed against lmod.
  • #1007137 filed against libranlip.
  • #1007184 filed against xrt.
  • #1007185 filed against btrfsmaintenance.

Testing framework The Reproducible Builds project runs a significant testing framework at tests.reproducible-builds.org, to check packages and other artifacts for reproducibility. This month, the following changes were made:

• Holger Levsen:
  • Replace a local copy of the dsa-check-running-kernel script with a packaged version. [ ]
  • Don t hide the status of offline hosts in the Jenkins shell monitor. [ ]
  • Detect undefined service problems in the node health check. [ ]
  • Update the sources.lst file for our mail server as its still running Debian buster. [ ]
  • Add our mail server to our node inventory so it is included in the Jenkins maintenance processes. [ ]
  • Remove the debsecan package everywhere; it got installed accidentally via the Recommends relation. [ ]
  • Document the usage of the osuosl174 host. [ ]

Regular node maintenance was also performed by Holger Levsen [ ], Vagrant Cascadian [ ][ ][ ] and Mattia Rizzolo.
If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

• IRC: #reproducible-builds on irc.oftc.net.
• Twitter: @ReproBuilds
• Mailing list: rb-general@lists.reproducible-builds.org

For many using Unix-derived systems today, we take for granted that /some/path and /some/path/ are the same. Most shells will even add a trailing slash for you when you press the Tab key after the name of a directory or a symbolic link to one. However, many programs treat these two paths as subtly different in certain cases, which I outline below, as all three have tripped me up in various ways¹.

POSIX and Coreutils Perhaps the trickiest use of the trailing slash in a distinguishing way is in POSIX² which states:

When the final component of a pathname is a symbolic link, the standard requires that a trailing <slash> causes the link to be followed. This is the behavior of historical implementations³. For example, for /a/b and /a/b/, if /a/b is a symbolic link to a directory, then /a/b refers to the symbolic link, and /a/b/ refers to the directory to which the symbolic link points.

This leads to some unexpected behavior. For example, if you have the following structure of a directory dir containing a file dirfile with a symbolic link link pointing to dir. (which will be used in all shell examples throughout this article):

$ ls -lR
.:
total 4
drwxr-xr-x 2 jacob jacob 4096 Apr  3 00:00 dir
lrwxrwxrwx 1 jacob jacob    3 Apr  3 00:00 link -> dir
./dir:
total 0
-rw-r--r-- 1 jacob jacob 0 Apr  3 00:12 dirfile

On Unixes such as MacOS, FreeBSD or Illumos⁴, you can move a directory through a symbolic link by using a trailing slash:

$ mv link/ otherdir
$ ls
link	otherdir

On Linux⁵, mv will not rename the indirectly referenced directory and not the symbolic link, when given a symbolic link with a trailing slash as the source to be renamed. despite the coreutils documentation s claims to the contrary⁶, instead failing with Not a directory:

$ mv link/ other
mv: cannot move 'link/' to 'other': Not a directory
$ mkdir otherdir
$ mv link/ otherdir
mv: cannot move 'link/' to 'otherdir/link': Not a directory
$ mv link/ otherdir/
mv: cannot move 'link/' to 'otherdir/link': Not a directory
$ mv link otherdirlink
$ ls -l otherdirlink
lrwxrwxrwx 1 jacob jacob 3 Apr  3 00:13 otherdirlink -> dir

This is probably for the best, as it is very confusing behavior. There is still one advantage the trailing slash has when using mv, even on Linux, in that is it does not allow you to move a file to a non-existent directory, or move a file that you expect to be a directory that isn t.

$ mv dir/dirfile nonedir/
mv: cannot move 'dir/dirfile' to 'nonedir/': Not a directory
$ touch otherfile
$ mv otherfile/ dir
mv: cannot stat 'otherfile/': Not a directory
$ mv otherfile dir
$ ls dir
dirfile  otherfile

However, Linux still exhibits some confusing behavior of its own, like when you attempt to remove link recursively with a trailing slash:

rm -rvf link/

Neither link nor dir are removed, but the contents of dir are removed:

removed 'link/dirfile'

Whereas if you remove the trailing slash, you just remove the symbolic link:

$ rm -rvf link
removed 'link'

While on MacOS, FreeBSD or Illumos⁴, rm will also remove the source directory:

$ rm -rvf link
link/dirfile
link/
$ ls
link

The find and ls commands, in contrast, behave the same on all three operating systems. The find command only searches the contents of the directory a symbolic link points to if the trailing slash is added:

$ find link -name dirfile
$ find link/ -name dirfile
link/dirfile

The ls command acts similarly, showing information on just a symbolic link by itself unless a trailing slash is added, at which point it shows the contents of the directory that it links to:

$ ls -l link
lrwxrwxrwx 1 jacob jacob 3 Apr  3 00:13 link -> dir
$ ls -l link/
total 0
-rw-r--r-- 1 jacob jacob 0 Apr  3 00:13 dirfile

rsync The command rsync handles a trailing slash in an unusual way that trips up many new users. The rsync man page notes:

You can think of a trailing / on a source as meaning copy the contents of this directory as opposed to copy the directory by name , but in both cases the attributes of the containing directory are transferred to the containing directory on the destination.

That is to say, if we had two folders a and b each of which contained some files:

$ ls -R .
.:
a  b
./a:
a1  a2
./b:
b1  b2

Running rsync -av a b moves the entire directory a to directory b:

$ rsync -av a b
sending incremental file list
a/
a/a1
a/a2
sent 181 bytes  received 58 bytes  478.00 bytes/sec
total size is 0  speedup is 0.00
$ ls -R b
b:
a  b1  b2
b/a:
a1  a2

While running rsync -av a/ b moves the contents of directory a to b:

$ rsync -av a/ b
sending incremental file list
./
a1
a2
sent 170 bytes  received 57 bytes  454.00 bytes/sec
total size is 0  speedup is 0.00
$ ls b
a1  a2	b1  b2

Dockerfile COPY The Dockerfile COPY command also cares about the presence of the trailing slash, using it to determine whether the destination should be considered a file or directory. The Docker documentation explains the rules of the command thusly:

COPY [--chown=<user>:<group>] <src>... <dest>

If <src> is a directory, the entire contents of the directory are copied, including filesystem metadata. Note: The directory itself is not copied, just its contents. If <src> is any other kind of file, it is copied individually along with its metadata. In this case, if <dest> ends with a trailing slash /, it will be considered a directory and the contents of <src> will be written at <dest>/base(<src>). If multiple <src> resources are specified, either directly or due to the use of a wildcard, then <dest> must be a directory, and it must end with a slash /. If <dest> does not end with a trailing slash, it will be considered a regular file and the contents of <src> will be written at <dest>. If <dest> doesn t exist, it is created along with all missing directories in its path.

This means if you had a COPY command that moved file to a nonexistent containerfile without the slash, it would create containerfile as a file with the contents of file.

COPY file /containerfile
container$ stat -c %F containerfile
regular empty file

Whereas if you add a trailing slash, then file will be added as a file under the new directory containerdir:

COPY file /containerdir/
container$ stat -c %F containerdir
directory

Interestingly, at no point can you copy a directory completely, only its contents. Thus if you wanted to make a directory in the new container, you need to specify its name in both the source and the destination:

COPY dir /dirincontainer
container$ stat -c %F /dirincontainer
directory

Dockerfiles do also make good use of the trailing slash to ensure they re doing what you mean by requiring a trailing slash on the destination of multiple files:

COPY file otherfile /othercontainerdir

results in the following error:

When using COPY with more than one source file, the destination must be a directory and end with a /

1. I m sure there are probably more than just these three cases, but these are the three I m familiar with. If you know of more, please tell me about them!.
2. Some additional relevant sections are the Path Resolution Appendix and the section on Symbolic Links.
3. The sentence This is the behavior of historical implementations implies that this probably originated in some ancient Unix derivative, possibly BSD or even the original Unix. I don t really have a source on that though, so please reach out if you happen to have any more knowledge on what this refers to.
4. I tested on MacOS 11.6.5, FreeBSD 12.0 and OmniOS 5.11 ²
5. unless the source is a directory trailing slashes give -ENOTDIR
6. In fairness to the coreutils maintainers, it seems to be true on all other Unix platforms, but it probably deserves a mention in the documentation when Linux is the most common platform on which coreutils is used. I should submit a patch.

Raspberry Pi computers require a piece of non-free software to boot the infamous raspi-firmware package. But for almost as long as there has been a Raspberry Pi to talk of (this year it turns 10 years old!), there have been efforts to get it to boot using only free software. How is it progressing? Michael Bishop (IRC user clever) explained today in the #debian-raspberrypi channel in OFTC that it advances far better than what I expected: It is even possible to boot a usable system under the RPi2 family! Just There is somewhat incomplete hardware support: For his testing, he has managed to use a xfce environment but over the composite (NTSC) video output, as HDMI initialization support is not there. However, he shared with me several interesting links and videos, and I told him I d share them there are still many issues; I do not believe it is currently worth it to make Debian images with this firmware. Before anything else: Go visit the librerpi/lk-overlay repository. Its README outlines hardware support for each of the RPi families; there is a binary build available with nixos if you want to try it out, and instructions to build it. But what clever showed me that made me write this post Is the amount of stuff you can do with the RPi s VPU (why Vision Vector Processing Unit and not the more familiar GPU, Graphical Processing Unit? I don t really know But I trust clever s definitions beyond how I trust my own ) before it loads an opearting system:

• 2D accel, using the closed firmware (regular raspi-firmware)
• Similar to the above, but running on the VPU, with no firmware blobs involved. Due to the lack of HDMI initialization code, this is filmed from an NTSC output. The garbling you can see happens when too many sprites collide in the same rows.
• This one really blew my mind: it shows Linux booting with the open firmware, while the VPU performs 2D and 3D animations in the background
• Just a 2D+3D demo, with no operating system involved

There s not too much I can add to this. I was just Truly amazed. And I hope to see the remaining hurdles for regular Linux booting on this range of machines with purely free software quickly go away! Packaging this for Debian? Well, not yet not so fast I first told clever we could push this firmware to experimental instead of unstable, as it is not yet ready for most production systems. However, pabs made some spot-on further questions. And yes, it requires installing three(!) different cross-compilers, one of which vc4-toolchain, for the VPU is free software, but not yet upstreamed, and hence is not available for Debian. Anyway, the talk continued long after I had to go. I have gone a bit over the backlog, but I have to leave now so that will be it as for this blog post

We are very pleased to announce that Infomaniak has committed to support DebConf22 as a Platinum sponsor. This is the fourth year in a row that Infomaniak is sponsoring The Debian Conference with the higher tier! Infomaniak is Switzerland's largest web-hosting company, also offering backup and storage services, solutions for event organizers, live-streaming and video on demand services. It wholly owns its datacenters and all elements critical to the functioning of the services and products provided by the company (both software and hardware). With this commitment as Platinum Sponsor, Infomaniak contributes to make possible our annual conference, and directly supports the progress of Debian and Free Software helping to strengthen the community that continues to collaborate on Debian projects throughout the rest of the year. Thank you very much Infomaniak, for your support of DebConf22! Become a sponsor too! DebConf22 will take place from July 17th to 24th, 2022 at the Innovation and Training Park (ITP) in Prizren, Kosovo, and will be preceded by DebCamp, from July 10th to 16th. And DebConf22 is still accepting sponsors! Interested companies and organizations may contact the DebConf team through sponsors@debconf.org, and visit the DebConf22 website at https://debconf22.debconf.org/sponsors/become-a-sponsor.

A new version 0.0.8 of RcppSpdlog is now on CRAN. RcppSpdlog bundles spdlog, a wonderful header-only C++ logging library with all the bells and whistles you would want that was written by Gabi Melman, and also includes fmt by Victor Zverovich. This release brings a new upstream release 1.10.0 of spdlog. The (minimal) NEWS entry for this release follows.

Changes in RcppSpdlog version 0.0.8 (2022-04-04)

• Upgraded to upstream releases spdlog 1.10.0

Courtesy of my CRANberries, there is also a diffstat report. More detailed information is on the RcppSpdlog page, or the package documention site. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Armadillo is a powerful and expressive C++ template library for linear algebra aiming towards a good balance between speed and ease of use with a syntax deliberately close to a Matlab. RcppArmadillo integrates this library with the R environment and language and is widely used by (currently) 972 other packages on CRAN, downloaded over 24 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 465 times according to Google Scholar. This release brings a new upstream release 11.0.0. We tested this very rigorously via three different RC release each of which got a full reverse-dependencies run (for which results are always logged here). The full set of changes (since the last CRAN release 0.10.8.1.0) follows.

Changes in RcppArmadillo version 0.11.0.0 (2022-04-04)

• Upgraded to Armadillo release 11.0.0 (Creme Brulee)
  • added variants of inv() and inv_sympd() that provide rcond (reciprocal condition number)
  • expanded inv() and inv_sympd() with options inv_opts::tiny and inv_opts::allow_approx
  • stricter handling of singular matrices by inv() and inv_sympd()
  • stricter handling of non-sympd matrices by inv() and inv_sympd()
  • stricter handling of non-finitie matrices by pinv()
  • more robust handling of rank deficient matrices by solve()
  • faster handling of diagonal matrices by rcond()
  • changed eigs_sym() and eigs_gen() to use higher quality RNG
  • quantile() and median() will now throw an exception if given matrices/vectors have NaN elements
  • workaround for yet another bug in Intel MKL
• Until May 2022, protect correction to Field behavior via define of RCPP_ARMADILLO_FIX_Field
• If a LAPACK installation with missing complex routines is found (as e.g. Ubuntu using 3.9.0) then the LAPACK unit test is skipped.

Changes in RcppArmadillo version 0.10.8.2.0 (2022-02-01)

• Upgraded to Armadillo release 10.8.2 (Realm Raider)
  • fix potential speed regression in pinv() and rank()

Courtesy of my CRANberries, there is a diffstat report relative to previous release. More detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the R-Forge page. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Previously: v5.9 Linux v5.10 was released in December, 2020. Here s my summary of various security things that I found interesting: AMD SEV-ES
While guest VM memory encryption with AMD SEV has been supported for a while, Joerg Roedel, Thomas Lendacky, and others added register state encryption (SEV-ES). This means it s even harder for a VM host to reconstruct a guest VM s state. x86 static calls
Josh Poimboeuf and Peter Zijlstra implemented static calls for x86, which operates very similarly to the static branch infrastructure in the kernel. With static branches, an if/else choice can be hard-coded, instead of being run-time evaluated every time. Such branches can be updated too (the kernel just rewrites the code to switch around the branch ). All these principles apply to static calls as well, but they re for replacing indirect function calls (i.e. a call through a function pointer) with a direct call (i.e. a hard-coded call address). This eliminates the need for Spectre mitigations (e.g. RETPOLINE) for these indirect calls, and avoids a memory lookup for the pointer. For hot-path code (like the scheduler), this has a measurable performance impact. It also serves as a kind of Control Flow Integrity implementation: an indirect call got removed, and the potential destinations have been explicitly identified at compile-time. network RNG improvements
In an effort to improve the pseudo-random number generator used by the network subsystem (for things like port numbers and packet sequence numbers), Linux s home-grown pRNG has been replaced by the SipHash round function, and perturbed by (hopefully) hard-to-predict internal kernel states. This should make it very hard to brute force the internal state of the pRNG and make predictions about future random numbers just from examining network traffic. Similarly, ICMP s global rate limiter was adjusted to avoid leaking details of network state, as a start to fixing recent DNS Cache Poisoning attacks. SafeSetID handles GID
Thomas Cedeno improved the SafeSetID LSM to handle group IDs (which required teaching the kernel about which syscalls were actually performing setgid.) Like the earlier setuid policy, this lets the system owner define an explicit list of allowed group ID transitions under CAP_SETGID (instead of to just any group), providing a way to keep the power of granting this capability much more limited. (This isn t complete yet, though, since handling setgroups() is still needed.) improve kernel s internal checking of file contents
The kernel provides LSMs (like the Integrity subsystem) with details about files as they re loaded. (For example, loading modules, new kernel images for kexec, and firmware.) There wasn t very good coverage for cases where the contents were coming from things that weren t files. To deal with this, new hooks were added that allow the LSMs to introspect the contents directly, and to do partial reads. This will give the LSMs much finer grain visibility into these kinds of operations. set_fs removal continues
With the earlier work landed to free the core kernel code from set_fs(), Christoph Hellwig made it possible for set_fs() to be optional for an architecture. Subsequently, he then removed set_fs() entirely for x86, riscv, and powerpc. These architectures will now be free from the entire class of kernel address limit attacks that only needed to corrupt a single value in struct thead_info. sysfs_emit() replaces sprintf() in /sys
Joe Perches tackled one of the most common bug classes with sprintf() and snprintf() in /sys handlers by creating a new helper, sysfs_emit(). This will handle the cases where kernel code was not correctly dealing with the length results from sprintf() calls, which might lead to buffer overflows in the PAGE_SIZE buffer that /sys handlers operate on. With the helper in place, it was possible to start the refactoring of the many sprintf() callers. nosymfollow mount option
Mattias Nissler and Ross Zwisler implemented the nosymfollow mount option. This entirely disables symlink resolution for the given filesystem, similar to other mount options where noexec disallows execve(), nosuid disallows setid bits, and nodev disallows device files. Quoting the patch, it is useful as a defensive measure for systems that need to deal with untrusted file systems in privileged contexts. (i.e. for when /proc/sys/fs/protected_symlinks isn t a big enough hammer.) Chrome OS uses this option for its stateful filesystem, as symlink traversal as been a common attack-persistence vector. ARMv8.5 Memory Tagging Extension support
Vincenzo Frascino added support to arm64 for the coming Memory Tagging Extension, which will be available for ARMv8.5 and later chips. It provides 4 bits of tags (covering multiples of 16 byte spans of the address space). This is enough to deterministically eliminate all linear heap buffer overflow flaws (1 tag for free , and then rotate even values and odd values for neighboring allocations), which is probably one of the most common bugs being currently exploited. It also makes use-after-free and over/under indexing much more difficult for attackers (but still possible if the target s tag bits can be exposed). Maybe some day we can switch to 128 bit virtual memory addresses and have fully versioned allocations. But for now, 16 tag values is better than none, though we do still need to wait for anyone to actually be shipping ARMv8.5 hardware. fixes for flaws found by UBSAN
The work to make UBSAN generally usable under syzkaller continues to bear fruit, with various fixes all over the kernel for stuff like shift-out-of-bounds, divide-by-zero, and integer overflow. Seeing these kinds of patches land reinforces the the rationale of shifting the burden of these kinds of checks to the toolchain: these run-time bugs continue to pop up. flexible array conversions
The work on flexible array conversions continues. Gustavo A. R. Silva and others continued to grind on the conversions, getting the kernel ever closer to being able to enable the -Warray-bounds compiler flag and clear the path for saner bounds checking of array indexes and memcpy() usage. That s it for now! Please let me know if you think anything else needs some attention. Next up is Linux v5.11.

2022, Kees Cook. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 License.