Today, after many years of hard work from many people, +ZFS for Linux finally entered +Debian. The package status can be seen on +the package tracker +for zfs-linux. and +the +team status page. If you want to help out, please join us. +The +source code is available via git on Alioth. It would also be +great if you could help out with +the dkms package, as +it is an important piece of the puzzle to get ZFS working.
+Two years ago, I had -a -look at trusted timestamping options available, and among -other things noted a still open -bug in the tsget script -included in openssl that made it harder than necessary to use openssl -as a trusted timestamping client. A few days ago I was told -the Norwegian government office DIFI is -close to releasing their own trusted timestamp service, and in the -process I was happy to learn about a replacement for the tsget script -using only curl:
- --openssl ts -query -data "/etc/shells" -cert -sha256 -no_nonce \ - | curl -s -H "Content-Type: application/timestamp-query" \ - --data-binary "@-" http://zeitstempel.dfn.de > etc-shells.tsr -openssl ts -reply -text -in etc-shells.tsr -- -
This produces a binary timestamp file (etc-shells.tsr) which can be -used to verify that the content of the file /etc/shell with the -calculated sha256 hash existed at the point in time when the request -was made. The last command extract the content of the etc-shells.tsr -in human readable form. The idea behind such timestamp is to be able -to prove using cryptography that the content of a file have not -changed since the file was stamped.
- -To verify that the file on disk match the public key signature in -the timestamp file, run the following commands. It make sure you have -the required certificate for the trusted timestamp service available -and use it to compare the file content with the timestamp. In -production, one should of course use a better method to verify the -service certificate.
- --wget -O ca-cert.txt https://pki.pca.dfn.de/global-services-ca/pub/cacert/chain.txt -openssl ts -verify -data /etc/shells -in etc-shells.tsr -CAfile ca-cert.txt -text -- -
Wikipedia have a lot more information about -trusted -Timestamping and -linked -timestamping, and there are several trusted timestamping services -around, both as commercial services and as free and public services. -Among the latter is -the -zeitstempel.dfn.de service mentioned above and -freetsa.org service linked to from the -wikipedia web site. I believe the DIFI service should show up on -https://tsa.difi.no, but it is not available to the public at the -moment. I hope this will change when it is into production. The -RFC 3161 trusted -timestamping protocol standard is even implemented in LibreOffice, -Microsoft Office and Adobe Acrobat, making it possible to verify when -a document was created.
- -I would find it useful to be able to use such trusted timestamp -service to make it possible to verify that my stored syslog files have -not been tampered with. This is not a new idea. I found one example -implemented on the Endian network appliances where -the -configuration of such feature was described in 2012.
- -But I could not find any free implementation of such feature when I -searched, so I decided to try to -build -a prototype named syslog-trusted-timestamp. My idea is to -generate a timestamp of the old log files after they are rotated, and -store the timestamp in the new log file just after rotation. This -will form a chain that would make it possible to see if any old log -files are tampered with. But syslog is bad at handling kilobytes of -binary data, so I decided to base64 encode the timestamp and add an ID -and line sequence numbers to the base64 data to make it possible to -reassemble the timestamp file again. To use it, simply run it like -this: - -
-syslog-trusted-timestamp /path/to/list-of-log-files -- -
This will send a timestamp from one or more timestamp services (not -yet decided nor implemented) for each listed file to the syslog using -logger(1). To verify the timestamp, the same program is used with the ---verify option:
- --syslog-trusted-timestamp --verify /path/to/log-file /path/to/log-with-timestamp -- -
The verification step is not yet well designed. The current -implementation depend on the file path being unique and unchanging, -and this is not a solid assumption. It also uses process number as -timestamp ID, and this is bound to create ID collisions. I hope to -have time to come up with a better way to handle timestamp IDs and -verification later.
- -Please check out -the -prototype for syslog-trusted-timestamp on github and send -suggestions and improvement, or let me know if there already exist a -similar system for timestamping logs already to allow me to join -forces with others with the same interest.
- -As usual, if you use Bitcoin and want to show your support of my -activities, please send Bitcoin donations to my address -15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.
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