Sequences not working with DROID Support simplified syntax

[ross-spencer]

It looks like there is still a shift between what can be interpreted from a DROID signature file and the DROID container signature file.

There is a related issue here: digital-preservation/droid#237

This XML should work, but it doesn't and it is certainly an unpublished specification from TNA.

<?xml version="1.0" encoding="UTF-8"?>
<FFSignatureFile xmlns="http://www.nationalarchives.gov.uk/pronom/SignatureFile" Version="1" DateCreated="2020-09-19T21:29:09">
 <InternalSignatureCollection>
  <InternalSignature ID="2" Specificity="Specific">
   <ByteSequence Reference="BOFoffset">
    <SubSequence Position="1" MinFragLength="0" SubSeqMinOffset="0" SubSeqMaxOffset="4">
     <Sequence>504B0304</Sequence>
    </SubSequence>
   </ByteSequence>
   <ByteSequence Reference="EOFoffset">
    <SubSequence Position="1" MinFragLength="0" SubSeqMinOffset="0" SubSeqMaxOffset="4">
     <Sequence>504B01{43-65531}504B0506{18-65531}</Sequence>
    </SubSequence>
   </ByteSequence>
  </InternalSignature>
  <InternalSignature ID="3" Specificity="Specific">
   <ByteSequence Reference="BOFoffset">
    <SubSequence Position="1" MinFragLength="0" SubSeqMinOffset="0" SubSeqMaxOffset="0">
     <Sequence>504B0304{26}5B436F6E74656E745F54797065735D2E786D6C20A2*504B0102*504B0506</Sequence>
    </SubSequence>
   </ByteSequence>
  </InternalSignature>
  <InternalSignature ID="4" Specificity="Specific">
   <ByteSequence Reference="BOFoffset">
    <SubSequence Position="1" MinFragLength="0" SubSeqMinOffset="0" SubSeqMaxOffset="0">
     <Sequence>D0CF11E0A1B11AE1{20}FEFF</Sequence>
    </SubSequence>
   </ByteSequence>
  </InternalSignature>
 </InternalSignatureCollection>
 <FileFormatCollection>
  <FileFormat ID="1" Name="Development Signature" PUID="dev/1" Version="1.0" MIMEType="application/octet-stream">
   <Extension>ext</Extension>
  </FileFormat>
  <FileFormat ID="2" Name="ZIP Format" PUID="x-fmt/263" Version="" MIMEType="application/zip">
   <InternalSignatureID>2</InternalSignatureID>
   <Extension>zip</Extension>
  </FileFormat>
  <FileFormat ID="3" Name="Microsoft Office Open XML" PUID=" fmt/189" Version="" MIMEType="application/octet-stream">
   <InternalSignatureID>3</InternalSignatureID>
  </FileFormat>
  <FileFormat ID="4" Name="OLE2 Compound Document Format" PUID=" fmt/111" Version="" MIMEType="application/octet-stream">
   <InternalSignatureID>4</InternalSignatureID>
  </FileFormat>
 </FileFormatCollection>
</FFSignatureFile>

To build the current development signatures in Siegfried we can do the following: ./roy build -droid development-signature-dev-1.xml -noreports -container container-signature-20200918.xml these will work there.

Notes on patterns

• Doesn't work: 504B030414{2}000800F0AB3051000000000000000002
• Doesn't work: 504B030414{2-4}000800F0AB3051000000000000000002
• Doesn't work: 504B030414*000800F0AB3051000000000000000002
• Doesn't work: 504B030414??08000800F0AB3051000000000000000002
         
• works: 504B030414[00:01]08000800F0AB3051000000000000000002      
• works: 'kml xmlns='
• works: 504B030414(00|01)08000800F0AB3051000000000000000002

[ross-spencer]

This is fixed for now by wiring in the PHP version of the code here which is pretty graceful, but adds complexity we don't need. But it works.

[ross-spencer]

I'll probably need to update this blog.

[ross-spencer]

NB. To be clear, this was always a mistaken view on my part. It may however be good if the signature file syntax accepted by DROID was simplified.

[ross-spencer]

NB. It looks like my syntax may be wrong so the following needs to be tried and tested:

  <InternalSignature ID="3" Specificity="Specific">
   <ByteSequence Reference="BOFoffset" Sequence="04??[01:0C][01:1F]{28}([41:5A]|[61:7A]){10}(43|44|46|4C|4E)"/>
  </InternalSignature>

[ross-spencer]

Some good progress here: https://github.com/ross-spencer/simpledroid