Search Results: "sez"

17 May 2020

Matthew Palmer: Private Key Redaction: UR DOIN IT RONG

Because posting private keys on the Internet is a bad idea, some people like to redact their private keys, so that it looks kinda-sorta like a private key, but it isn t actually giving away anything secret. Unfortunately, due to the way that private keys are represented, it is easy to redact a key in such a way that it doesn t actually redact anything at all. RSA private keys are particularly bad at this, but the problem can (potentially) apply to other keys as well. I ll show you a bit of Inside Baseball with key formats, and then demonstrate the practical implications. Finally, we ll go through a practical worked example from an actual not-really-redacted key I recently stumbled across in my travels.

The Private Lives of Private Keys Here is what a typical private key looks like, when you come across it: 
-----BEGIN RSA PRIVATE KEY-----
MGICAQACEQCxjdTmecltJEz2PLMpS4BXAgMBAAECEDKtuwD17gpagnASq1zQTYEC
CQDVTYVsjjF7IQIJANUYZsIjRsR3AgkAkahDUXL0RSECCB78r2SnsJC9AghaOK3F
sKoELg==
-----END RSA PRIVATE KEY-----
Obviously, there s some hidden meaning in there computers don t encrypt things by shouting BEGIN RSA PRIVATE KEY! , after all. What is between the BEGIN/END lines above is, in fact, a base64-encoded DER format ASN.1 structure representing a PKCS#1 private key. In simple terms, it s a list of numbers very important numbers. The list of numbers is, in order:
  • A version number (0);
  • The public modulus , commonly referred to as n ;
  • The public exponent , or e (which is almost always 65,537, for various unimportant reasons);
  • The private exponent , or d ;
  • The two private primes , or p and q ;
  • Two exponents, which are known as dmp1 and dmq1 ; and
  • A coefficient, known as iqmp .

Why Is This a Problem? The thing is, only three of those numbers are actually required in a private key. The rest, whilst useful to allow the RSA encryption and decryption to be more efficient, aren t necessary. The three absolutely required values are e, p, and q. Of the other numbers, most of them are at least about the same size as each of p and q. So of the total data in an RSA key, less than a quarter of the data is required. Let me show you with the above toy key, by breaking it down piece by piece1:
  • MGI DER for this is a sequence
  • CAQ version (0)
  • CxjdTmecltJEz2PLMpS4BX n
  • AgMBAA e
  • ECEDKtuwD17gpagnASq1zQTY d
  • ECCQDVTYVsjjF7IQ p
  • IJANUYZsIjRsR3 q
  • AgkAkahDUXL0RS dmp1
  • ECCB78r2SnsJC9 dmq1
  • AghaOK3FsKoELg== iqmp
Remember that in order to reconstruct all of these values, all I need are e, p, and q and e is pretty much always 65,537. So I could redact almost all of this key, and still give all the important, private bits of this key. Let me show you: 
-----BEGIN RSA PRIVATE KEY-----
..............................................................EC
CQDVTYVsjjF7IQIJANUYZsIjRsR3....................................
........
-----END RSA PRIVATE KEY-----
Now, I doubt that anyone is going to redact a key precisely like this but then again, this isn t a typical RSA key. They usually look a lot more like this: 
-----BEGIN RSA PRIVATE KEY-----
MIIEogIBAAKCAQEAu6Inch7+mWtKn+leB9uCG3MaJIxRyvC/5KTz2fR+h+GOhqj4
SZJobiVB4FrE5FgC7AnlH6qeRi9MI0s6dt5UWZ5oNIeWSaOOeNO+EJDUkSVf67wj
SNGXlSjGAkPZ0nRJiDjhuPvQmdW53hOaBLk5udxPEQbenpXAzbLJ7wH5ouLQ3nQw
HwpwDNQhF6zRO8WoscpDVThOAM+s4PS7EiK8ZR4hu2toon8Ynadlm95V45wR0VlW
zywgbkZCKa1IMrDCscB6CglQ10M3Xzya3iTzDtQxYMVqhDrA7uBYRxA0y1sER+Rb
yhEh03xz3AWemJVLCQuU06r+FABXJuY/QuAVvQIDAQABAoIBAFqwWVhzWqNUlFEO
PoCVvCEAVRZtK+tmyZj9kU87ORz8DCNR8A+/T/JM17ZUqO2lDGSBs9jGYpGRsr8s
USm69BIM2ljpX95fyzDjRu5C0jsFUYNi/7rmctmJR4s4uENcKV5J/++k5oI0Jw4L
c1ntHNWUgjK8m0UTJIlHbQq0bbAoFEcfdZxd3W+SzRG3jND3gifqKxBG04YDwloy
tu+bPV2jEih6p8tykew5OJwtJ3XsSZnqJMwcvDciVbwYNiJ6pUvGq6Z9kumOavm9
XU26m4cWipuK0URWbHWQA7SjbktqEpxsFrn5bYhJ9qXgLUh/I1+WhB2GEf3hQF5A
pDTN4oECgYEA7Kp6lE7ugFBDC09sKAhoQWrVSiFpZG4Z1gsL9z5YmZU/vZf0Su0n
9J2/k5B1GghvSwkTqpDZLXgNz8eIX0WCsS1xpzOuORSNvS1DWuzyATIG2cExuRiB
jYWIJUeCpa5p2PdlZmBrnD/hJ4oNk4oAVpf+HisfDSN7HBpN+TJfcAUCgYEAyvY7
Y4hQfHIdcfF3A9eeCGazIYbwVyfoGu70S/BZb2NoNEPymqsz7NOfwZQkL4O7R3Wl
Rm0vrWT8T5ykEUgT+2ruZVXYSQCKUOl18acbAy0eZ81wGBljZc9VWBrP1rHviVWd
OVDRZNjz6nd6ZMrJvxRa24TvxZbJMmO1cgSW1FkCgYAoWBd1WM9HiGclcnCZknVT
UYbykCeLO0mkN1Xe2/32kH7BLzox26PIC2wxF5seyPlP7Ugw92hOW/zewsD4nLze
v0R0oFa+3EYdTa4BvgqzMXgBfvGfABJ1saG32SzoWYcpuWLLxPwTMsCLIPmXgRr1
qAtl0SwF7Vp7O/C23mNukQKBgB89DOEB7xloWv3Zo27U9f7nB7UmVsGjY8cZdkJl
6O4LB9PbjXCe3ywZWmJqEbO6e83A3sJbNdZjT65VNq9uP50X1T+FmfeKfL99X2jl
RnQTsrVZWmJrLfBSnBkmb0zlMDAcHEnhFYmHFuvEnfL7f1fIoz9cU6c+0RLPY/L7
n9dpAoGAXih17mcmtnV+Ce+lBWzGWw9P4kVDSIxzGxd8gprrGKLa3Q9VuOrLdt58
++UzNUaBN6VYAe4jgxGfZfh+IaSlMouwOjDgE/qzgY8QsjBubzmABR/KWCYiRqkj
qpWCgo1FC1Gn94gh/+dW2Q8+NjYtXWNqQcjRP4AKTBnPktEvdMA=
-----END RSA PRIVATE KEY-----
People typically redact keys by deleting whole lines, and usually replacing them with [...] and the like. But only about 345 of those 1588 characters (excluding the header and footer) are required to construct the entire key. You can redact about 4/5ths of that giant blob of stuff, and your private parts (or at least, those of your key) are still left uncomfortably exposed.

But Wait! There s More! Remember how I said that everything in the key other than e, p, and q could be derived from those three numbers? Let s talk about one of those numbers: n. This is known as the public modulus (because, along with e, it is also present in the public key). It is very easy to calculate: n = p * q. It is also very early in the key (the second number, in fact). Since n = p * q, it follows that q = n / p. Thus, as long as the key is intact up to p, you can derive q by simple division.

Real World Redaction At this point, I d like to introduce an acquaintance of mine: Mr. Johan Finn. He is the proud owner of the GitHub repo johanfinn/scripts. For a while, his repo contained a script that contained a poorly-redacted private key. He since deleted it, by making a new commit, but of course because git never really deletes anything, it s still available. Of course, Mr. Finn may delete the repo, or force-push a new history without that commit, so here is the redacted private key, with a bit of the surrounding shell script, for our illustrative pleasure: 
#Add private key to .ssh folder
cd /home/johan/.ssh/
echo  "-----BEGIN RSA PRIVATE KEY-----
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK
 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:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::.::
:::::::::::::::::::::::::::.::::::::::::::::::::::::::::::::::::
LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLlL
 
 
 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-----END RSA PRIVATE KEY-----" >> id_rsa
Now, if you try to reconstruct this key by removing the obvious garbage lines (the ones that are all repeated characters, some of which aren t even valid base64 characters), it still isn t a key at least, openssl pkey doesn t want anything to do with it. The key is very much still in there, though, as we shall soon see. Using a gem I wrote and a quick bit of Ruby, we can extract a complete private key. The irb session looks something like this: 
>> require "derparse"
>> b64 = <<EOF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>> b64 += <<EOF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>> der = b64.unpack("m").first
>> c = DerParse.new(der).first_node.first_child
>> version = c.value
=> 0
>> c = c.next_node
>> n = c.value
=> 80071596234464993385068908004931... # (etc)
>> c = c.next_node
>> e = c.value
=> 65537
>> c = c.next_node
>> d = c.value
=> 58438813486895877116761996105770... # (etc)
>> c = c.next_node
>> p = c.value
=> 29635449580247160226960937109864... # (etc)
>> c = c.next_node
>> q = c.value
=> 27018856595256414771163410576410... # (etc)
What I ve done, in case you don t speak Ruby, is take the two chunks of plausible-looking base64 data, chuck them together into a variable named b64, unbase64 it into a variable named der, pass that into a new DerParse instance, and then walk the DER value tree until I got all the values I need. Interestingly, the q value actually traverses the split in the two chunks, which means that there s always the possibility that there are lines missing from the key. However, since p and q are supposed to be prime, we can sanity check them to see if corruption is likely to have occurred: 
>> require "openssl"
>> OpenSSL::BN.new(p).prime?
=> true
>> OpenSSL::BN.new(q).prime?
=> true
Excellent! The chances of a corrupted file producing valid-but-incorrect prime numbers isn t huge, so we can be fairly confident that we ve got the real p and q. Now, with the help of another one of my creations we can use e, p, and q to create a fully-operational battle key: 
>> require "openssl/pkey/rsa"
>> k = OpenSSL::PKey::RSA.from_factors(p, q, e)
=> #<OpenSSL::PKey::RSA:0x0000559d5903cd38>
>> k.valid?
=> true
>> k.verify(OpenSSL::Digest::SHA256.new, k.sign(OpenSSL::Digest::SHA256.new, "bob"), "bob")
=> true
and there you have it. One fairly redacted-looking private key brought back to life by maths and far too much free time. Sorry Mr. Finn, I hope you re not still using that key on anything Internet-facing.

What About Other Key Types? EC keys are very different beasts, but they have much the same problems as RSA keys. A typical EC key contains both private and public data, and the public portion is twice the size so only about 1/3 of the data in the key is private material. It is quite plausible that you can redact an EC key and leave all the actually private bits exposed.

What Do We Do About It? In short: don t ever try and redact real private keys. For documentation purposes, just put KEY GOES HERE in the appropriate spot, or something like that. Store your secrets somewhere that isn t a public (or even private!) git repo. Generating a dummy private key and sticking it in there isn t a great idea, for different reasons: people have this odd habit of reusing demo keys in real life. There s no need to encourage that sort of thing.
  1. Technically the pieces aren t 100% aligned with the underlying DER, because of how base64 works. I felt it was easier to understand if I stuck to chopping up the base64, rather than decoding into DER and then chopping up the DER.

16 April 2020

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, March 2020

A Debian LTS logo Like each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In March, 252 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation March was a strange month for many people all over the globe. Here we ll just express our hopes that you are and will be well! LTS gained a new contributor in March, Anton Gladky, however he then decided to become active later this year. Similarly Hugo Lefeuvre notified us that he ll be inactive in April. In case you missed it (or missed to act), please read this post about keeping Debian 8 Jessie alive for longer than 5 years. If you expect to have Debian 8 servers/devices running after June 30th 2020, and would like to have security updates for them, please get in touch with Freexian. Hurry up: the end of Jessie LTS is coming in less than three months! The security tracker currently lists 25 packages with a known CVE and the dla-needed.txt file has 23 packages needing an update. Thanks to our sponsors New sponsors are in bold.

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25 March 2020

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, February 2020

A Debian LTS logo Like each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In February, 226 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation February began as rather calm month and the fact that more contributors have given back unused hours is an indicator of this calmness and also an indicator that contributing to LTS has become more of a routine now, which is good. In the second half of February Holger Levsen (from LTS) and Salvatore Bonaccorso (from the Debian Security Team) met at SnowCamp in Italy and discussed tensions and possible improvements from and for Debian LTS. The security tracker currently lists 25 packages with a known CVE and the dla-needed.txt file has 21 packages needing an update. Thanks to our sponsors New sponsors are in bold.

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17 November 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, October 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In October, about 197 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours increased slightly to 183 hours per month. With the increasing number of security issues to deal with, and with the number of open issues not really going down, I decided to bump the funding target to what amounts to 1.5 full-time position. The security tracker currently lists 50 packages with a known CVE and the dla-needed.txt file 36 (we re a bit behind in CVE triaging apparently). Thanks to our sponsors New sponsors are in bold.

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20 October 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, September 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In August, about 170 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours is the same as last month. But we have a new sponsor in the pipe. The security tracker currently lists 52 packages with a known CVE and the dla-needed.txt file 49. The number of packages with open issues decreased slightly compared to last month but we re not yet back to the usual situation. Thanks to our sponsors New sponsors are in bold.

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17 September 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, August 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In August, about 189 work hours have been dispatched among 12 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours is the same as last month. The security tracker currently lists 59 packages with a known CVE and the dla-needed.txt file 60. The number of packages with open issues decreased slightly compared to last month but we re not yet back to the usual situation. The number of CVE to fix per package tends to increase due to the increased usage of fuzzers. Thanks to our sponsors New sponsors are in bold.

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18 August 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, July 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In July, about 181 work hours have been dispatched among 11 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours increased slightly with two new sponsors: Leibniz Rechenzentrum (silver sponsor) and Catalyst IT Ltd (bronze sponsor). The security tracker currently lists 74 packages with a known CVE and the dla-needed.txt file 64. The number of packages with open issues increased of almost 50% compared to last month. Hopefully this backlog will get cleared up when the unused hours will actually be done. In any case, this evolution is worth watching. Thanks to our sponsors New sponsors are in bold.

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11 July 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, June 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In May, about 161 work hours have been dispatched among 11 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours increased slightly with one new bronze sponsor and another silver sponsor is in the process of joining. The security tracker currently lists 49 packages with a known CVE and the dla-needed.txt file 54. The number of open issues is close to last month. Thanks to our sponsors New sponsors are in bold.

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13 June 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, May 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In May, about 182 work hours have been dispatched among 11 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours did not change and we are thus still a little behind our objective. The security tracker currently lists 44 packages with a known CVE and the dla-needed.txt file 42. The number of open issues is close to last month. Thanks to our sponsors New sponsors are in bold (none this month unfortunately).

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16 May 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, April 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In April, about 190 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours decreased slightly and we re now again a little behind our objective. The security tracker currently lists 54 packages with a known CVE and the dla-needed.txt file 37. The number of open issues is comparable to last month. Thanks to our sponsors New sponsors are in bold.

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13 April 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, March 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In March, about 190 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours has been unchanged but will likely decrease slightly next month as one sponsor will not renew his support (because they have switched to CentOS). The security tracker currently lists 52 packages with a known CVE and the dla-needed.txt file 40. The number of open issues continued its slight increase not worrisome yet but we need to keep an eye on this situation. Thanks to our sponsors New sponsors are in bold.

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16 March 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, February 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In January, about 154 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours increased slightly thanks to Bearstech and LiHAS joining us. The security tracker currently lists 45 packages with a known CVE and the dla-needed.txt file 39. The number of open issues continued its slight increase, this time it could be explained by the fact that many contributors did not spend all the hours allocated (for various reasons). There s nothing worrisome at this point. Thanks to our sponsors New sponsors are in bold.

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13 February 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, January 2017

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In January, about 159 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours increased slightly thanks to Exonet joining us. The security tracker currently lists 37 packages with a known CVE and the dla-needed.txt file 36. The situation is roughly similar to last month even though the number of open issues increased slightly. Thanks to our sponsors New sponsors are in bold.

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16 January 2017

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, December 2016

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In December, about 175 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours did not increase but a new silver sponsor is in the process of joining. We are only missing another silver sponsor (or two to four bronze sponsors) to reach our objective of funding the equivalent of a full time position. The security tracker currently lists 31 packages with a known CVE and the dla-needed.txt file 27. The situation improved a little bit compared to last month. Thanks to our sponsors New sponsors are in bold.

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16 December 2016

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, November 2016

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In October, about 150 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours did not change this month and in fact we haven t had any new sponsor since September. We still need a couple of supplementary sponsors to reach our objective of funding the equivalent of a full time position. The security tracker currently lists 40 packages with a known CVE and the dla-needed.txt file 36. We don t seem to really catch up the small backlog. The reasons are not clear but I noticed that there are a few packages that take a lot of time due to the number of issues found with fuzzers. We also handle many issues that the security team ends up classifying as not worth an update because we add the package to dla-needed.txt before the security team has done its review and nobody checks afterwards. Thanks to our sponsors New sponsors are in bold.

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14 November 2016

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, October 2016

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In October, about 175 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours did not change this month. We still need a couple of supplementary sponsors to reach our objective of funding the equivalent of a full time position. The security tracker currently lists 34 packages with a known CVE and the dla-needed.txt file 29. The situation improved slightly compared to last month. Thanks to our sponsors New sponsors are in bold.

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31 October 2016

Chris Lamb: Free software activities in October 2016

Here is my monthly update covering what I have been doing in the free software world (previously):

Debian & Reproducible builds

Whilst anyone can inspect the source code of free software for malicious flaws, most GNU/Linux distributions provide binary (or "compiled") packages to end users. The motivation behind the Reproducible Builds effort is to allow verification that no flaws have been introduced either maliciously and accidentally during this compilation process by promising identical binary packages are always generated from a given source.

  • Presented a talk entitled "Reproducible Builds" talk at Software Freedom Kosova, in Prishtina, Republic of Kosovo.

  • I filed my 2,500th bug in the Debian BTS: #840972: golang-google-appengine: accesses the internet during build.

  • In order to build packages reproducibly, one not only needs identical sources but also some external and sharable definition of the environment used for a particular build, stipulating such things such as the version numbers of the required build-dependencies. It is not currently clear how to handle these .buildinfo files after the archive software has processed them and how to make them available to the world so I started development on a proof-of-concept server to see what issues arise in practice. It is available at buildinfo.debian.net.

  • Chaired an IRC meeting and ran a poll to determine a regular time .

  • Submitted two design proposals to our wiki page.

  • Improvements to our tests.reproducible-builds.org testing framework:

    • Move regular "Scheduled in..." messages to the #debian-reproducible-changes IRC channel.
    • Use our log_info method instead of manual echo calls.
    • Correct an "all sources packages" "all source packages" typo.
    • Submit .buildinfo files to buildinfo.debian.net.
    • Create GPG key on nodes for buildinfo.debian.net at deploy time, not "lazily".

My work in the Reproducible Builds project was also covered in our weekly reports. (#75, #76, #77 & #78).

I also submitted 14 patches to fix specific reproducibility issues in bio-eagle, cf-python, fastx-toolkit, fpga-icestorm, http-icons, lambda-align, mypy, playitslowly, seabios, stumpwm, sympa, tj3, wims-help & xotcl.
Debian LTS

This month I have been paid to work 13 hours on Debian Long Term Support (LTS). In that time I did the following:
  • Seven days of "frontdesk" duties, triaging CVEs, etc.
  • Issued DLA 647-1 for freeimage correcting an out-of-bounds write vulnerability in the XMP image handling functionality.
  • Issued DLA 649-1 for python-django fixing a possible CSRF protection bypass on sites that use Google Analytics.
  • Issued DLA 654-1 for libxfixes preventing an integer overflow when a malicious client sent INT_MAX as a "length".
  • Issued DLA 662-1 for quagga correcting a programming error where two constants were confused that could cause stack overrun in IPv6 routing code.
  • Issued DLA 688-1 for cairo to prevent a DoS attack where a malicious SVG could generate invalid pointers.
Uploads
  • gunicorn:
    • 19.6.0-7 Set supplementary groups when changing uid, add an example systemd .service file to gunicorn-examples, and expand README.Debian to make it clearer what to do now that /etc/gunicorn.d has been removed.
    • 19.6.0-8 Correct previous supplementary groups patch to be compatible with Python 3.
  • redis:
    • 3:3.2.4-2 Ensure that sentinel's configuration actually writes to a pidfile location so that systemd can detect that the daemon has started.
    • 3:3.2.5-1 New upstream release.
  • libfiu:
    • 0.94-8 Fix FTBFS under Bash due to lack of && in debian/rules.
    • 0.94-9 Ensure the build is reproducible by sorting injected modules.
  • aptfs (2:0.8-2) Minor cosmetic changes.

NMUs
  • libxml-dumper-perl (0.81-1.2) Move away from a unsupported debhelper compat level 4.
  • netatalk (2.2.5-1.1) Drop build-dependency on hardening-includes.

QA uploads
  • anon-proxy (00.05.38+20081230-4) Move to a supported debhelper compatibility level 9.
  • ara (1.0.32) Make the build reproducible.
  • binutils-m68hc1x (1:2.18-8) Make the build reproducible & move to a supported debhelper compatibility level.
  • fracplanet (0.4.0-5) Make the build reproducible.
  • libnss-ldap (265-5) Make the build reproducible.
  • python-uniconvertor (1.1.5-3) Fix an "option release requires an argument" FTBFS. (#839375)
  • ripole (0.2.0+20081101.0215-3) Actually include the ripole binary in package. (#839919) & enable hardening flags.
  • twitter-bootstrap (2.0.2+dfsg-10) Fix incorrect copyright formatting when building under Bash. (#824592)
  • zpaq (1.10-3) Make the build reproducible.
Debian FTP Team

As a Debian FTP assistant I ACCEPTed 147 packages: ace-link, amazon-s2n, avy, basez, bootstrap-vz, bucklespring, camitk, carettah, cf-python, debian-reference, dfcgen-gtk, efivar, entropybroker, fakesleep, gall, game-data-packager, gitano, glare, gnome-panel, gnome-shell-extension-dashtodock, gnome-shell-extension-refreshwifi, gnome-shell-extension-remove-dropdown-arrows, golang-github-gogits-go-gogs-client, golang-github-gucumber-gucumber, golang-github-hlandau-buildinfo, golang-github-hlandau-dexlogconfig, golang-github-hlandau-goutils, golang-github-influxdata-toml, golang-github-jacobsa-crypto, golang-github-kjk-lzma, golang-github-miekg-dns, golang-github-minio-sha256-simd, golang-github-nfnt-resize, golang-github-nicksnyder-go-i18n, golang-github-pointlander-compress, golang-github-pointlander-jetset, golang-github-pointlander-peg, golang-github-rfjakob-eme, golang-github-thecreeper-go-notify, golang-github-twstrike-gotk3adapter, golang-github-unknwon-goconfig, golang-gopkg-dancannon-gorethink.v1, golang-petname, haskell-argon2, haskell-binary-parsers, haskell-bindings-dsl, haskell-deriving-compat, haskell-hackage-security, haskell-hcwiid, haskell-hsopenssl-x509-system, haskell-megaparsec, haskell-mono-traversable-instances, haskell-prim-uniq, haskell-raaz, haskell-readable, haskell-readline, haskell-relational-record, haskell-safe-exceptions, haskell-servant-client, haskell-token-bucket, haskell-zxcvbn-c, irclog2html, ironic-ui, lace, ledger, libdancer2-plugin-passphrase-perl, libdatetime-calendar-julian-perl, libdbix-class-optimisticlocking-perl, libdbix-class-schema-config-perl, libgeo-constants-perl, libgeo-ellipsoids-perl, libgeo-functions-perl, libgeo-inverse-perl, libio-async-loop-mojo-perl, libmojolicious-plugin-assetpack-perl, libmojolicious-plugin-renderfile-perl, libparams-validationcompiler-perl, libspecio-perl, libtest-time-perl, libtest2-plugin-nowarnings-perl, linux, lua-scrypt, mono, mutt-vc-query, neutron, node-ansi-font, node-buffer-equal, node-defaults, node-formatio, node-fs-exists-sync, node-fs.realpath, node-is-buffer, node-jison-lex, node-jju, node-jsonstream, node-kind-of, node-lex-parser, node-lolex, node-loud-rejection, node-random-bytes, node-randombytes, node-regex-not, node-repeat-string, node-samsam, node-set-value, node-source-map-support, node-spdx-correct, node-static-extend, node-test, node-to-object-path, node-type-check, node-typescript, node-unset-value, nutsqlite, opencv, openssl1.0, panoramisk, perl6, pg-rage-terminator, pg8000, plv8, puppet-module-oslo, pymoc, pyramid-jinja2, python-bitbucket-api, python-ceilometermiddleware, python-configshell-fb, python-ewmh, python-gimmik, python-jsbeautifier, python-opcua, python-pyldap, python-s3transfer, python-testing.common.database, python-testing.mysqld, python-testing.postgresql, python-wheezy.template, qspeakers, r-cran-nleqslv, recommonmark, rolo, shim, swift-im, tendermint-go-clist, tongue, uftrace & zaqar-ui.

19 October 2016

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, September 2016

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In September, about 152 work hours have been dispatched among 13 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours reached 172 hours per month thanks to maxcluster GmbH joining as silver sponsor and RHX Srl joining as bronze sponsor. We only need a couple of supplementary sponsors now to reach our objective of funding the equivalent of a full time position. The security tracker currently lists 39 packages with a known CVE and the dla-needed.txt file 34. It s a small bump compared to last month but almost all issues are affected to someone. Thanks to our sponsors New sponsors are in bold.

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13 September 2016

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, August 2016

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In August, 140 work hours have been dispatched among 10 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours rised to 167 hours per month thanks to UR Communications BV joining as gold sponsor (funding 1 day of work per month)! In practice, we never distributed this amount of work per month because some sponsors did not renew in time and some of them might not even be able to renew at all. The security tracker currently lists 31 packages with a known CVE and the dla-needed.txt file 29. It s a small bump compared to last month but almost all issues are affected to someone. Thanks to our sponsors New sponsors are in bold.

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17 August 2016

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, July 2016

A Debian LTS logoLike each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In July, 136.6 work hours have been dispatched among 11 paid contributors. Their reports are available: Evolution of the situation The number of sponsored hours jumped to 159 hours per month thanks to GitHub joining as our second platinum sponsor (funding 3 days of work per month)! Our funding goal is getting closer but it s not there yet. The security tracker currently lists 22 packages with a known CVE and the dla-needed.txt file likewise. That s a sharp decline compared to last month. Thanks to our sponsors New sponsors are in bold.

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