Non-conventional Digital Signatures and Their Implementations—A Review

Abstract

Esta es la versión de autor de la comunicación de congreso publicada en: This is an author produced version of a paper published in: Abstract. The current technological scenario determines a profileration of trust domains, which are usually defined by validating the digital identity linked to each user. This validation entails critical assumptions about the way users' privacy is handled, and this calls for new methods to construct and treat digital identities. Considering cryptography, identity management has been constructed and managed through conventional digital signatures. Nowadays, new types of digital signatures are required, and this transition should be guided by rigorous evaluation of the theoretical basis, but also by the selection of properly verified software means. This latter point is the core of this paper. We analyse the main non-conventional digital signatures that could endorse an adequate tradeoff betweeen security and privacy. This discussion is focused on practical software solutions that are already implemented and available online. The goal is to help security system designers to discern identity management functionalities through standard cryptographic software libraries.

Analysis of the Cryptographic Tools for Blockchain and Bitcoin

“…It should be noted that there are several types of signatures, and each of them has its corresponding protocol, specifically designed to consider certain particular situations not included in the general and standard approach of a classic digital signature [18]. In the next paragraphs, some of these types of signatures, which are used in blockchain, are briefly presented.…”

Combining Usability and Privacy Protection in Free-Access Public Cloud Storage Servers: Review of the Main Threats and Challenges

“…Therefore, in this cloud services, anonymous authentication mechanisms are mandatory if the user really needs to get an adequate privacy in the cloud [29]. A way to achieve this type of authentication is through non-conventional digital signatures, like group signatures, which allow members of a group of signers to issue signatures on behalf of the group that can be verified without telling which specific member issued it [30].…”

“…Although it is possible to reach a conclusion about physical identity, it is not easy to establish a relationship between physical identity and digital identity. Cryptography provides the means for associating a digital identity to a user through asymmetric cryptography [30]. Consequently, the verification of the integrity of IT assets has been conceived and managed through conventional digital signatures.…”

“…In some situations, for example, it is necessary to design a signature scheme in which the message or document has to be signed by multiple users (e.g., if we are dealing with a committee that must sign the whole document). On this ground, we have to take into account that there exist over 60 digital signature models [30], whose classification is not easy, as they have a wide set of different characteristics. This being the case, group signatures could be used as anonymous authentication methods in the cloud.…”

Embedding an Identity-Based Short Signature as a Digital Watermark

“…Figure 3 shows an example image (a), the same image encrypted with IBC (b) and the resulting image after embedding the IBS-1 signature into it. The theoretical specification of a cryptographic system should be complemented by a properly engineered and rigorously verified implementation [27]. We have used the jPair [28] cryptographic library to implement the IBS-1 signature.…”