blog/archive/2017/06/06.rss

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   4                 <title>Petter Reinholdtsen - Entries from June 2017</title>
   5                 <description>Entries from June 2017</description>
   6                 <link>http://people.skolelinux.org/pere/blog/</link>
   7
   8
   9         <item>
  10                 <title>Idea for storing trusted timestamps in a Noark 5 archive</title>
  11                 <link>http://people.skolelinux.org/pere/blog/Idea_for_storing_trusted_timestamps_in_a_Noark_5_archive.html</link>
  12                 <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Idea_for_storing_trusted_timestamps_in_a_Noark_5_archive.html</guid>
  13                 <pubDate>Wed, 7 Jun 2017 21:40:00 +0200</pubDate>
  14                 <description>&lt;p&gt;&lt;em&gt;This is a copy of
  15 &lt;a href=&quot;https://lists.nuug.no/pipermail/nikita-noark/2017-June/000297.html&quot;&gt;an
  16 email I posted to the nikita-noark mailing list&lt;/a&gt;.  Please follow up
  17 there if you would like to discuss this topic.  The background is that
  18 we are making a free software archive system based on the Norwegian
  19 &lt;a href=&quot;https://www.arkivverket.no/forvaltning-og-utvikling/regelverk-og-standarder/noark-standarden&quot;&gt;Noark
  20 5 standard&lt;/a&gt; for government archives.&lt;/em&gt;&lt;/p&gt;
  21
  22 &lt;p&gt;I&#39;ve been wondering a bit lately how trusted timestamps could be
  23 stored in Noark 5.
  24 &lt;a href=&quot;https://en.wikipedia.org/wiki/Trusted_timestamping&quot;&gt;Trusted
  25 timestamps&lt;/a&gt; can be used to verify that some information
  26 (document/file/checksum/metadata) have not been changed since a
  27 specific time in the past.  This is useful to verify the integrity of
  28 the documents in the archive.&lt;/p&gt;
  29
  30 &lt;p&gt;Then it occured to me, perhaps the trusted timestamps could be
  31 stored as dokument variants (ie dokumentobjekt referered to from
  32 dokumentbeskrivelse) with the filename set to the hash it is
  33 stamping?&lt;/p&gt;
  34
  35 &lt;p&gt;Given a &quot;dokumentbeskrivelse&quot; with an associated &quot;dokumentobjekt&quot;,
  36 a new dokumentobjekt is associated with &quot;dokumentbeskrivelse&quot; with the
  37 same attributes as the stamped dokumentobjekt except these
  38 attributes:&lt;/p&gt;
  39
  40 &lt;ul&gt;
  41
  42 &lt;li&gt;format -&gt; &quot;RFC3161&quot;
  43 &lt;li&gt;mimeType -&gt; &quot;application/timestamp-reply&quot;
  44 &lt;li&gt;formatDetaljer -&gt; &quot;&amp;lt;source URL for timestamp service&amp;gt;&quot;
  45 &lt;li&gt;filenavn -&gt; &quot;&amp;lt;sjekksum&amp;gt;.tsr&quot;
  46
  47 &lt;/ul&gt;
  48
  49 &lt;p&gt;This assume a service following
  50 &lt;a href=&quot;https://tools.ietf.org/html/rfc3161&quot;&gt;IETF RFC 3161&lt;/a&gt; is
  51 used, which specifiy the given MIME type for replies and the .tsr file
  52 ending for the content of such trusted timestamp.  As far as I can
  53 tell from the Noark 5 specifications, it is OK to have several
  54 variants/renderings of a dokument attached to a given
  55 dokumentbeskrivelse objekt.  It might be stretching it a bit to make
  56 some of these variants represent crypto-signatures useful for
  57 verifying the document integrity instead of representing the dokument
  58 itself.&lt;/p&gt;
  59
  60 &lt;p&gt;Using the source of the service in formatDetaljer allow several
  61 timestamping services to be used.  This is useful to spread the risk
  62 of key compromise over several organisations.  It would only be a
  63 problem to trust the timestamps if all of the organisations are
  64 compromised.&lt;/p&gt;
  65
  66 &lt;p&gt;The following oneliner on Linux can be used to generate the tsr
  67 file.  $input is the path to the file to checksum, and $sha256 is the
  68 SHA-256 checksum of the file (ie the &quot;&lt;sjekksum&gt;.tsr&quot; value mentioned
  69 above).&lt;/p&gt;
  70
  71 &lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
  72 openssl ts -query -data &quot;$inputfile&quot; -cert -sha256 -no_nonce \
  73   | curl -s -H &quot;Content-Type: application/timestamp-query&quot; \
  74       --data-binary &quot;@-&quot; http://zeitstempel.dfn.de &gt; $sha256.tsr
  75 &lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;
  76
  77 &lt;p&gt;To verify the timestamp, you first need to download the public key
  78 of the trusted timestamp service, for example using this command:&lt;/p&gt;
  79
  80 &lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
  81 wget -O ca-cert.txt \
  82   https://pki.pca.dfn.de/global-services-ca/pub/cacert/chain.txt
  83 &lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;
  84
  85 &lt;p&gt;Note, the public key should be stored alongside the timestamps in
  86 the archive to make sure it is also available 100 years from now.  It
  87 is probably a good idea to standardise how and were to store such
  88 public keys, to make it easier to find for those trying to verify
  89 documents 100 or 1000 years from now. :)&lt;/p&gt;
  90
  91 &lt;p&gt;The verification itself is a simple openssl command:&lt;/p&gt;
  92
  93 &lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
  94 openssl ts -verify -data $inputfile -in $sha256.tsr \
  95   -CAfile ca-cert.txt -text
  96 &lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;
  97
  98 &lt;p&gt;Is there any reason this approach would not work?  Is it somehow against
  99 the Noark 5 specification?&lt;/p&gt;
 100 </description>
 101         </item>
 102
 103         <item>
 104                 <title>Når nynorskoversettelsen svikter til eksamen...</title>
 105                 <link>http://people.skolelinux.org/pere/blog/N_r_nynorskoversettelsen_svikter_til_eksamen___.html</link>
 106                 <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/N_r_nynorskoversettelsen_svikter_til_eksamen___.html</guid>
 107                 <pubDate>Sat, 3 Jun 2017 08:20:00 +0200</pubDate>
 108                 <description>&lt;p&gt;&lt;a href=&quot;http://www.aftenposten.no/norge/Krever-at-elever-ma-fa-annullert-eksamen-etter-rot-med-oppgavetekster-622459b.html&quot;&gt;Aftenposten
 109 melder i dag&lt;/a&gt; om feil i eksamensoppgavene for eksamen i politikk og
 110 menneskerettigheter, der teksten i bokmåls og nynorskutgaven ikke var
 111 like.  Oppgaveteksten er gjengitt i artikkelen, og jeg ble nysgjerring
 112 på om den fri oversetterløsningen
 113 &lt;a href=&quot;https://www.apertium.org/&quot;&gt;Apertium&lt;/a&gt; ville gjort en bedre
 114 jobb enn Utdanningsdirektoratet.  Det kan se slik ut.&lt;/p&gt;
 115
 116 &lt;p&gt;Her er bokmålsoppgaven fra eksamenen:&lt;/p&gt;
 117
 118 &lt;blockquote&gt;
 119 &lt;p&gt;Drøft utfordringene knyttet til nasjonalstatenes og andre aktørers
 120 rolle og muligheter til å håndtere internasjonale utfordringer, som
 121 for eksempel flykningekrisen.&lt;/p&gt;
 122
 123 &lt;p&gt;Vedlegge er eksempler på tekster som kan gi relevante perspektiver
 124 på temaet:&lt;/p&gt;
 125 &lt;ol&gt;
 126 &lt;li&gt;Flykningeregnskapet 2016, UNHCR og IDMC
 127 &lt;li&gt;«Grenseløst Europa for fall» A-Magasinet, 26. november 2015
 128 &lt;/ol&gt;
 129
 130 &lt;/blockquote&gt;
 131
 132 &lt;p&gt;Dette oversetter Apertium slik:&lt;/p&gt;
 133
 134 &lt;blockquote&gt;
 135 &lt;p&gt;Drøft utfordringane knytte til nasjonalstatane sine og rolla til
 136 andre aktørar og høve til å handtera internasjonale utfordringar, som
 137 til dømes *flykningekrisen.&lt;/p&gt;
 138
 139 &lt;p&gt;Vedleggja er døme på tekster som kan gje relevante perspektiv på
 140 temaet:&lt;/p&gt;
 141
 142 &lt;ol&gt;
 143 &lt;li&gt;*Flykningeregnskapet 2016, *UNHCR og *IDMC&lt;/li&gt;
 144 &lt;li&gt;«*Grenseløst Europa for fall» A-Magasinet, 26. november 2015&lt;/li&gt;
 145 &lt;/ol&gt;
 146
 147 &lt;/blockquote&gt;
 148
 149 &lt;p&gt;Ord som ikke ble forstått er markert med stjerne (*), og trenger
 150 ekstra språksjekk.  Men ingen ord er forsvunnet, slik det var i
 151 oppgaven elevene fikk presentert på eksamen.  Jeg mistenker dog at
 152 &quot;andre aktørers rolle og muligheter til ...&quot; burde vært oversatt til
 153 &quot;rolla til andre aktørar og deira høve til ...&quot; eller noe slikt, men
 154 det er kanskje flisespikking.  Det understreker vel bare at det alltid
 155 trengs korrekturlesning etter automatisk oversettelse.&lt;/p&gt;
 156 </description>
 157         </item>
 158
 159         </channel>
 160 </rss>