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Preservation Procedure Policy: Develop Integrity Measures |
| Related Guidance Policy |
Bit preservation |
| Definition/ Description |
Integrity or fixity check: “A mechanism to verify that a digital object has not been altered in an undocumented manner. Checksums, message digests and digital signatures are examples of tools to run fixity checks. Fixity information, the information created by these fixity checks, provides evidence for the integrity and authenticity of the digital objects and are essential to enabling trust.” (Source: NDSA )
The organisation needs to develop measures to monitor the bit integrity. As in the definition the integrity measures could consists of adding checksums, digital signatures etc. Regular checks need to be planned in order to monitor the situation in the archive.
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| Why |
Bit integrity needs to be checked on a regular basis to ensure that no changes to the digital material have occurred.
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| Risks |
Lack of procedures for integrity measures may cause unnoticed loss of data.
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| Life cycle stage |
Create and , Preservation Planning, Ingest, Preservation Action |
Stakeholder
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Technology Manager: responsible for ensuring the proper systems for bit preservation
Operational Manager/Information Operator/System Architect/Technology Operator/Solution Provider: responsible for administrating systems and performing bit preservation
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| Cross Reference |
Functional Preservation
Authenticity
Checksum
Integrity
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| Examples |
University of Minnesota: ”The University Digital Conservancy maintains fixity (bitstream integrity) for all digital objects submitted in the UDC. This is accomplished using a checksum algorithm (MD5) that verifies that the bitstream of a digital object matches its original bitstream (from date of original deposit in the UDC).” Source:, http://conservancy.umn.edu/pol-preservation.jsp
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| Control Policy |
For collection Y:
- File checksum algorithm MUST be <value>
- Filechecksum-recalculation date <= today – 2 years_ _
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| Questions to foster discussions |
- Does your organisation have written procedures describing the complete procedure for monitoring integrity of the digital objects (plan, do, check, act)?
- Does your organisation require checksums from the depositor?
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