Threats to legal electronic storage: analysis and countermeasures

In the last years, public administration and private companies have been involved in the process of document legal electronic storage, consisting in converting paper documents into digital ones, storing them on optical supports and developing databases to enable an effective classification of the resulting huge amount of information. In this respect, law establishes the use of digital signature to guarantee both the provenance and the integrity of digital documents. In the recent literature, a vulnerability of enveloping digital signature, based on a novel mechanism allowing ambiguous presentation of electronic documents, has been addressed. In this paper, we show that such an issue poses serious threats over archived documents (like legal acts and e-invoices), since this way an attacker is allowed to produce a certified copy of a signed document that could show a content completely different from that of the original document. A strategy to tackle this threat is also proposed.