27 research outputs found
Redactable Signatures for Signed CDA Documents
[[abstract]]The Clinical Document Architecture, introduced
by Health Level Seven, is a XML-based standard intending
to specify the encoding, structure, and semantics of clinical
documents for exchange. Since the clinical document is in
XML form, its authenticity and integrity could be guaranteed
by the use of the XML signature published by W3C.
While a clinical document wants to conceal some personal
or private information, the document needs to be redacted.
It makes the signed signature of the original clinical
document not be verified. The redactable signature is thus
proposed to enable verification for the redacted document.
Only a little research does the implementation of the
redactable signature, and there still not exists an appropriate
scheme for the clinical document. This paper will investigate
the existing web-technologies and find a compact and
applicable model to implement a suitable redactable
signature for the clinical document viewer.[[notice]]補正完畢[[incitationindex]]SC
A General Framework for Redactable Signatures and New Constructions
A redactable signature scheme (RSS) allows removing parts of a signed message by any party without invalidating the respective signature. State-of-the-art constructions thereby focus on messages represented by one specific data structure, e.g., lists, sets or trees, and adjust the security model accordingly. To overcome the necessity for this myriad of models, we present a general framework covering arbitrary data-structures and even more sophisticated possibilities. For example, we cover fixed elements which must not be redactable and dependencies between elements. Moreover, we introduce the notion of designated redactors, i.e., the signer can give some extra information to selected entities which become redactors. In practice, this often allows to obtain more efficient schemes. We then present two RSSs; one for sets and one for lists, both constructed from any EUF-CMA secure signature scheme and indistinguishable cryptographic accumulators in a black-box way and show how the concept of designated redactors can be used to increase the efficiency of these schemes. Finally, we present a black-box construction of a designated redactor RSS by combining an RSS for sets with non-interactive zero knowledge proof systems. All the three constructions presented in this paper provide transparency, which is an important property, but quite hard to achieve, as we also conceal the length of the original message and the positions of the redactions
Fully Invisible Protean Signatures Schemes
Protean Signatures (PS), recently introduced by Krenn et al. (CANS \u2718), allow a semi-trusted third party, named the sanitizer, to modify a signed message in a controlled way.
The sanitizer can
edit signer-chosen parts to arbitrary bitstrings, while the sanitizer can also redact
admissible parts, which are also chosen by the signer. Thus, PSs generalize both redactable signature (RSS) and sanitizable signature (SSS)
into a single notion.
However, the current definition of invisibility does not prohibit that an outsider can decide which
parts of a message are redactable - only which parts can be edited are hidden. This negatively
impacts on the privacy guarantees provided by the state-of-the-art definition.
We extend PSs to be fully invisible.
This strengthened notion guarantees that an outsider can neither decide which parts of a message can be edited nor which
parts can be redacted. To achieve our goal, we introduce the new notions of Invisible RSSs and Invisible Non-Accountable SSSs (SSS\u27), along with a consolidated framework for aggregate signatures.
Using those building blocks, our resulting construction is significantly
more efficient than the original scheme by Krenn et al., which we demonstrate in a prototypical implementation
Verifiably encrypted cascade-instantiable blank signatures to secure progressive decision management
National Research Foundation (NRF) Singapore under NC