Long-term validation (LTV)

Long-Term Validation (LTV) and Long-Term Archival (LTA) keep eIDAS electronic signatures and seals verifiable for decades using archive timestamps.

Long-Term Validation (LTV) keeps an electronic signature or electronic seal verifiable long after it was created. The problem: certificates expire, revocation services go offline and algorithms weaken. The solution: embed everything a validator will need - the certificate chain, revocation data (CRL/OCSP) and timestamps - inside the signature itself (the B-LT profile of the AdES formats, defined in ETSI standards). In PDF documents this is widely known as PAdES LTV, where the material is stored in the file's Document Security Store, a feature popularised by Adobe.

For decade-scale preservation, Long-Term Archival (LTA) adds periodic archive timestamps: each new timestamp re-seals the whole structure with current cryptography before the previous one weakens. Under eIDAS, a qualified preservation service (Article 34) - and, under eIDAS 2.0, qualified electronic archiving - offers this as a managed trust service.