A partition record has a long life: challenge actions, tax effects, and successive transmissions of the assets may require it to be consulted many years later. Long-term digital preservation is not 'just keeping the PDF'; it is a discipline with its own rules to prevent the technical degradation of the evidence.
Formats designed to last
PDF/A is the ISO 19005 standard designed for long-term preservation: it embeds fonts, prohibits external content and removes elements that may behave differently over time. For tabular data, CSV with UTF-8 encoding without BOM and strict JSON play the same role: open, simple formats, readable without proprietary software.
Signatures with timestamps and advanced format
For a signature to remain valid fifteen years from now, more than signing is needed: PAdES-LTA (Long Term Archival) and XAdES-LTA allow including validation information (certificate chain, revocation lists, qualified eIDAS timestamps) within the document itself. A future authority can thus verify validity without depending on the online availability of any specific provider.
Additional cryptographic layer: hash chain
On top of the signature, a hash chain that links each record to the immediately preceding one adds resilience against archive tampering: altering an old record without it showing would require rewriting the entire subsequent chain. It is the principle of append-only logs applied to the document repository.
Operational strategy
- Archival in at least two distinct physical locations, with verified periodic replication.
- Annual automated check of hashes and signatures; any discrepancy escalates as an incident.
- Planned migration when a format or algorithm becomes obsolete (e.g. SHA-1 → SHA-256).
- Accessible catalogue allowing a record to be located by case number, date or parties.