A New Approach for Electronic Signature
Gianluca Lax, Francesco Buccafurri, Serena Nicolazzo, Antonino Nocera and Lidia Fotia
DIIES Department, University of Reggio Calabria, Reggio Calabria, Italy
Electronic Signature, Digital Signature, Online Social Network, Twitter.
There are many application contexts in which guaranteeing authenticity and integrity of documents isessential.
In these cases, the typical solution relies on digital signature, which is based on the use of a PKI infrastructure
and suitable devices (smart card or token USB). For several reasons, including certificate and device cost,
many countries, such as the United States, the European Union, India, Brazil and Australia, have introduced
the possibility to use simple generic electronic signature, which is less secure but reduces the drawbacks of
digital signature.In this paper, we propose a new type of electronic signature that is based on the use of social
networks. We formalize the proposal in a generic scenario and then, show a possible implementation on
Twitter. Our proposal is proved to be secure, cheap and simple to adopt.
Digital signature is a tool used in several contexts to
exchange documents by guaranteeing their authentic-
ity and integrity. As digitally signed documents have
full legal validity, they can be used in e-commerce, e-
government, dematerialization processes, and so on.
To be used in open environments like the Inter-
net, digital signature needs a public key infrastructure
to identify the signer. Public key infrastructure (PKI)
(Ko´scielny et al., 2013; He et al., 2014) was designed
to permit the binding between the subject and the pub-
lic key by means of a digital certificate issued by the
Certification Authority (CA). PKI relies on a hierar-
chical architecture and a strong trust-based model. In
particular, a digital certificate includes a serial num-
ber (i.e. an identifier unique within the CA scope), the
subject identity, the issuer identity, the validity period,
the certificate policies of applicability, the usages for
which the key has been authorized by the digital sig-
nature of the CA that issued the certificate. An advan-
tage of PKI is that a smart card or similar device can
store the user’s certificate and corresponding private
The main drawback of digital signature is the need
of having a public key infrastructure (PKI) and/or
a physical device (typically a smart card or a token
USB), or the need of securely storing a private key.
This can increase the cost of this solution or reduce
its usability.
Also the possibility of using remote signing ser-
vices, such as HSM, does not help. Hardware Secu-
rity Modules (HSMs) (Sustek, 2011; Mavrovouniotis
and Ganley, 2014; Kim et al., 2014) are devices used
for data encryption and decryption and host one or
more cryptographic keys that respond to automated
or manual commands. They safeguards and man-
ages digital keys for strong authentication and have
the capability to detect an attack on their surface and
securely delete the sensitive content stored in their
Due to the drawbacks derived from the use of dig-
ital signature, in several countries, such as the United
States, the European Union, India, Brazil and Aus-
tralia, the possibility to use simple generic electronic
signature has been introduced. Differently from digi-
tal signature, electronic signature is a weaker way of
signing documents, because it does not require any
additional measure of security (in particular, a public
key infrastructure and a physical device). No stan-
dard technology or implementation of electronic sig-
nature exists, so that proprietary software to gener-
ate and validate is used. The most important advan-
tage of electronic signature is that it can be imple-
mented more easily than digital signature, but accept-
ing a lower level of security.
Electronic signatures can be used in closed do-
mains where users agree on a signature protocol that
(1) allows the identification of the signer, (2) creates a
connection between signer and document and (3) de-
tects any change to the document after the signature is
applied. Clearly, the security of the protocol depends
Lax, G., Buccafurri, F., Nicolazzo, S., Nocera, A. and Fotia, L.
A New Approach for Electronic Signature.
DOI: 10.5220/0005743404400447
In Proceedings of the 2nd Inter national Conference on Information Systems Security and Privacy (ICISSP 2016), pages 440-447
ISBN: 978-989-758-167-0
2016 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
on its implementation and must be evaluated.
In this paper, we propose a new approach for e-
signature solutions that does not rely on a public key
infrastructure or device or private keys, which are
substituted by the use of social networks (Buccafurri
et al., 2014c). Social networks have grown massively
(Nocera and Ursino, 2012) and nowadays most of the
people has at least an account in one of them (Buc-
cafurri et al., 2013; Buccafurri et al., 2014d). In this
paper, the social network is used as “device” enabling
the generation of the signature and also as trusted-
third-party allowing signature sharing. Our approach
shows important characteristics of cheapness, usabil-
ity, and, more importantly, security.
The analysis of protocol security shows that the
proposed e-signature approach is able to guarantee
document authenticity, document integrity and non-
repudiation against attacks that an adversary can carry
The paper is organized as follows. In the next sec-
tion, we discuss related work. In Section 3, we define
the model and describe how to generate and verify a
signature. In Section 4, we analyze the security of our
solution. Section 5 shows an instantiation of the so-
lution that uses Twitter as social network. Finally, in
Section 6, we draw our conclusions and sketch possi-
ble future work.
In this section, we survey the most relevant signature
techniques proposed in the literature.
Conditional Signatures were originally introduced
by Lee et al. (Lee and Kim, 2002) to implement fair
exchange of digital signatures in untrusted environ-
ments and do not require the card to have a user in-
terface or any special peripheral (like Clarke et al.
(Clarke et al., 2002)).
Berta et al. (Berta et al., 2004) propose a method
to generate, instead of an ordinary signature, a condi-
tional signature such that it is guaranteed that the con-
dition can not become true before a certain amount
of time has passed. This should leave time for the
user to move to a trusted terminal for checking the
signatures generated by the card and to enforce that
the conditions of the fake signatures can ever become
true. Since this approach requires the smart card to
know the current time but most smart cards have no
internal clock, it could be acquired from a secure time
servers as described in Berta et al. (Berta and Va-
jda, 2003). Moreover, this proposal requires the user
to store every signed message, because this message
has to be checked later by means of a trusted termi-
nal. Since it may be infeasible for C to store large
message, this problem can be solved by outsourcing
the logging function to an external logserver. There-
fore, even though the required hardware is the stan-
dard one, a trusted third party is required.
The drawback of conditional signature is to re-
quire a significant load for the user, who has to split
the signature task into two phases, delaying the effec-
tive conclusion of the procedure at validation-time.
Weak signature was introduced by T. Rabin and
Ben-Or (Rabin and Ben-Or, 1989; Rabin, 1994) to
solve a problem (Verifiable Secret Sharing (Chor
et al., 1985)) motivated by a question of general multi-
party secure computation in the unconditional setting
(network of untappable channels). They provide a
form of authentication for which the on-line partici-
pation of a third party is needed.
Check vectors are related to work on authenti-
cation codes (Gilbert et al., 1974; Simmons, 1985)
and on universal classes of hash functions (Carter and
Wegman, 1977). The weak signature scheme relies on
the presence of an on-line trusted server that partici-
pates in the creation of every signature, and also par-
ticipates whenever a signed message holder wishes to
prove to anyone that a signature is valid. This trusted
server stores and retrieves information received from
the signing agency and the message holder, and com-
putes certain linear combinations of values it receives.
Using the idea of check vectors, T. Rabin (Rabin
and Ben-Or, 1989) presents a weak signature scheme,
called Information Checking Protocol. Consider that
the intermediary wishes to have a message s signed
by the dealer. In the first phase, the original message
holder intermediary ends up with the “signed mes-
sage” s, y, while a third party RCV ends up with the
check information a, b. Anyone can determine the
validity of the signature by asking RCV to reveal the
check information. The signature is weak, because
the assistance of this third party is needed to verify a
Another signature scheme in the unconditional
setting was introduced by Chaum and Roijakkers
(Chaum and Roijakkers, 1991). It satisfies a stronger
set of conditions than Rabin’s Information Checking
Protocol, at a great increase in communication cost.
Visual cryptography (Sharma and Srivastava,
2014; Shaji et al., 2014; Naor and Shamir, 1995) is a
type of cryptographic scheme which can decode con-
cealed images without any cryptographic computa-
tion. Naor et al. (Naor and Pinkas, 1997) suggest a
number of transparency-based methods for visual au-
thentication and identification, and give rigorousanal-
ysis of their security.
(Matsumoto, 1998) presents human-friendly iden-
A New Approach for Electronic Signature
tification schemes such that a human prover knowing
a secret key in his brain is asked a visual question by a
verifier, which then checks if an answer sent from the
prover matches the question with respect to the key.
Ateniese et al. (Ateniese et al., 1996) propose a
visual cryptography scheme for a set of participants
to encode a secret image into many secondary im-
ages in such a way that any participant receives one
secondary image and only qualified subsets of par-
ticipants can “visually” recover the secret image, but
non-qualified sets of participants have no information,
in an information theoretical sense, on the original im-
age. This scheme does not require the participants to
perform any cryptographic computation.
The methods of visual cryptography can be bro-
ken by attacker exploiting human interaction. More-
over the user load can be considered very relevant.
In this context, our paper proposes a lightweight
protocol that allows us to know who created an elec-
tronic document and to ensure that this document has
not been altered since that person created it. Differ-
ently from the above solutions (conditional signature
and weak signature), our proposal does not rely on
certification authority, asymmetric cryptography, or
signature device.
In this section, we present the abstract model to real-
ize e-signatures by social networks. We observe that
this is the main added value w.r.t. the proposal de-
scribed in (Buccafurri et al., 2014a), in which no the-
oretic model has been considered.
The main entities of our model are:
a social network
that supports the following
1. the possibility to post textual information after
authentication for registered users;
2. the automatical notification about the post ac-
tivity of other selected users;
3. the possibility to search for an information
posted by a user.
Observe that the first characteristic is common
to the most social networks, whereas the remain-
ing ones are not supported by all social networks.
Twitter is an example of social networks support-
ing these three features: indeed, users are noti-
fied about tweets coming from their follows and a
search is done by hashtags.
a company
, the environment in which this kind
of signature has validity.
the set of persons who can sign and verify a sig-
nature. In the following, we will denoted by
signer of a document.
The model is composed of the following proce-
Registration. The procedure is carried out when
a new person is added in such a way that he/she
is enable to sign a document. In this phase, this
person is identified and associated with a profile
in the social network
. Moreover, the company
requires to be notified about any posting activity
of this person in
Then, the person posts on
the first message, say
registration message of the type hI, ID
i, where I
contains the real-life identity of
and ID
is the
identifier of
in the social network
. This al-
lows us to establish a trusted relationship between
the external user account that pertains to the com-
pany and the registered Twitter account. For ex-
ample, the email address of a user could be used
as identifier to be associated with the Twitter ac-
The company is notified about this post and, in
turn, posts the same message in its public space.
Signature. This procedure is carried out by the
on the document D to be signed. Let ID
be the identifier of
in the social network
h be a cryptographic hash function.
This procedure is composed of two steps. In the
first step,
posts on
the signature message de-
fined as hh(D), ID
i (i.e., the document digest and
his account identifier).
In the second step, the company is notified about
this post and, in turn, posts the same message
hh(D), ID
i. We denoted the latter message
posted by
as confirmation message.
Verification. This procedure is used to check the
validity of a signature. Let D be the document
whose signature has to be verified. The protocol
works as follow. First, the digest h(D) is com-
puted. Then, h(D) is searched among the pub-
lic information posted in the social network
. If
h(D) is not found, then the signature on the docu-
ment D is detected as invalid (i.e., either wrong or
absent signature). Otherwise,
we have two possibilities:
1. Both a signature message and a confirmation
message hh(D), ID
i are found. In this case, the
verification procedure returns that the signature
on D is valid.
2. Either a signature message or a confirmation
message hh(D), ID
i is found. In this case, the
ICISSP 2016 - 2nd International Conference on Information Systems Security and Privacy
verification procedure returns that an attack oc-
curred. Section 4 is devoted to describe how to
detect the type of attack and how to decide if
the signature can be considered valid or not.
It is worth noting that, in case of multiple signers
and, thus, of multiple signature messages found,
the above verification is repeated for each signer,
thus obtaining a result (valid, invalid or attack) for
each signer.
Revocation. This procedure is carried out to re-
voke the signature grant to a person (for example,
in case of dismissal of an employee). We recall
that in the registration procedure of a person, the
company requires to be notified about any posting
activity in
of this person in such a way to gen-
erate the confirmation message for each signature
message produced by this person. By the proce-
dure of revocation, this notification is removed so
that no confirmation message will be produced by
the company. Consequently, any successive sig-
nature message posted by this person will not be
confirmed by the company and, thus, the verifica-
tion of this signature will fail.
The conceptual model underlying our proposal of
e-signature requires message exchanges among the
parties, message search in the social network, and en-
abling activity notification.
Clearly, how to technically implement these fea-
tures is strongly related to the actually social network
on which such a proposal is implemented, so that this
aspect is not addressed in this section. However, in
Section 5, we will instantiate our proposal on a real
social network and these issues will be faced.
In this section, we prove that the model defined above
guarantees the security properties required for digi-
tal signature, which are document authenticity, docu-
ment integrity and non-repudiation.
In our analysis, our (realistic) assumptions are:
1. the cryptographic hash function h withstands all
known types of attacks in such a way that pre-
image, second pre-image and collision resistance
are assured;
2. the social network
is a trusted party;
3. the information posted by the users on the social
network cannot be compromise.
In our threat model, the attacker is either the com-
pany, or a signer, or a third person. We do not consider
the collusion between company and signer as this is
meaningless (indeed, in a typical scenario this does
not give them any advantage – they could agree to ob-
tain the same result without carry out any attack).
Now, we analyze the security properties of our
proposal with respect to several attacks (Lax et al.,
Document Authenticity. A document is authentic if
it has been signed by the claimed signer. In our
solution, once a signature is verified valid for a
signer S, the personal information of S (name, sur-
name, etc.) can be found in the registration mes-
sage posted by both the signer and the company.
This allows us to associate a document signature
with a real-life identity.
An attack on document authenticity is carried out
in different ways (we consider only the most sig-
nificant cases):
The adversary creates a fake account on
by using the personal information of a victim.
However, because the registration protocol has
not been done, the company is not notified of
signatures produced by this fake account so that
no confirmation messages will be generated.
Consequently, a signature done by the adver-
sary is not considered valid.
The adversary adds or corrupts an already
posted signature message and the correspond-
ing confirmation message by substituting h(D)
with h(D
), where D
is a new document, in
such a way that it appears a valid signature of
the victim on D
. However, an external adver-
sary cannot modify posted message due to As-
sumption 2. Moreover, whenever the adversary
is the company, it is able to modify only the
confirmation message, not the signature (As-
sumption 2). Therefore the attack fails.
Document Integrity. This property ensures that any
modification of the binary representation of the
document done after the signature is detected.
This property is guaranteed by the presence of the
document digest h(D) both in the signature mes-
sage and the confirmation message. Any change
to the document after the signature results in the
change of the digest, which, thus, will be different
from h(D).
An attack on document integrity would success
only if the attacker is able to modify the signed
document yet keeping its digest equal to h(D).
However, this is unfeasible thanks to Assump-
tion 1, which guarantees that the cryptographic
hash function has pre-image resistance.
Another possibility of attack is that the digest
of the document is modified in the signature
A New Approach for Electronic Signature
or/and the confirmation message. In this case,
an external attacker cannot modify such mes-
sages thank to assumption 2. If the signer or the
company can act as attacker, the modification
of only one of such messages is possible, so that
the signature is not considered valid. Moreover,
the mismatch between signature and confirma-
tion message is used to detect this attack.
Non-repudiation. This property assures that the real
signer cannot challenge the authorship or validity
of the signature. In this case, the attacker is clearly
the signer.
A first possibility of attack is to claim that the
signature message has been produced by some-
one else who violated his/her account. As-
sumption 1 assures that this is unfeasible, so
that repudiation is not admitted.
The signer deletes the signature message from
the posted information. As a consequence, now
only the confirmation message for that signa-
ture is found. The signature is not considered
valid, however a warning for a possible (repu-
diation) attack is raised.
Document Immutability. This property requires that
the content shown by the signed document can-
not change after the signature. It is worth noting
that this property is different from the document
integrity discussed above, because document in-
tegrity refers to changes in the bits composing the
document. In contrast, document immutability is
related to the possibility for documents of hav-
ing an ambiguous presentation depending on sys-
tem or external parameters (Alsaid and Mitchell,
2005). The typical case is that of digital docu-
ments containing macros or JavaScript, which es-
tablish what should be displayed on the basis of
some conditions (for example, a date). Clearly,
this does not produce any change on the bits of
the signature, so that document integrity property
is satisfied.
As done for digital signature, this attack is con-
trasted by forcing that signed document cannot
contain dynamic content. Interestingly, the pres-
ence of dynamic content can be detected, so that
a signature done on a non-static document is con-
sidered not valid.
In this section, we show an application of our proposal
in a real-life case, and discuss the requirements of the
real social network to use as underlying layer.
The scenario considered is that of a university
that needs an e-signature procedure for internal docu-
ments (learning plans, exam results, travel reimburse-
ment requests, and so on).
In this case, the actors are the university, which
plays the role of the company
of our model, and
its students and employees, who compose the set of
persons who can sign and verify a signature.
The social network
underlying the proposal
1. allow registered users to post textual information
after authentication;
2. allow users to be automatically notified about the
post activity of other selected users;
3. allow for the search for an information posted by
a user.
Among all social networks, Twitter is one of
the most famous complying such requirements. In-
deed, (1) registered users can post textual informa-
tion, named tweet, and they must be authenticate to
post anything; (2) users can add friendship relations
with other users in such a way to be automatically
notified about their tweets, and (3) Twitter supports
textual search among tweets by means of a mecha-
nism based on hashtags. Concerning this aspect, in
Twitter people use the hashtag symbol
before a rele-
vant keyword or phrase (no spaces) to categorize their
tweets by keywords. Moreover, hashtags are indexed
to make it easier to find a conversation about a topic.
In the implementation of our solution, the first step
is the registration. Each student and employee is iden-
tified and associated with a profile in Twitter. Also
the university has its Twitter profile, and adds a fol-
low relationship towards registered students and em-
ployees, in such a way that the university account re-
ceives their tweets. Assume that
is the account
of the university in Twitter (we recall that a Twitter
screen-name starts with the symbol @ and represents
the unique Twitter identifier for a given user).
Each registered student and employee posts the
registration message on Twitter: an example of this
message for the user John Smith is hJohn Smith,
@John Smithi, where the first item is the real-life
identity of the user, whereas the second item is his
identifier on Twitter. The university account receives
this tweet and, in turn, posts the same information in
its public space.
A snapshot of the publication of the registration
message on Twitter is illustrated in Figure 1.
Consider now the instantiation of the signa-
ture procedure. When an employee or a stu-
dent, say John Smith, needs to sign a document
D, first the digest of D is computed by SHA-256,
ICISSP 2016 - 2nd International Conference on Information Systems Security and Privacy
Figure 1: An instantiation of the registration procedure.
which is considered robust against all known attacks.
Then, he posts on Twitter the signature message
ZKFuRFMY, @John Smithi, where the first item is
the base64 representation of the document digest.
Observe that the digest of the document is hashtagged
(see the symbol # at the beginning): this results in the
indexing of this tweet in such a way to be found in
case of search.
Next, the university account receives this tweet
and, in turn, posts the same tweet in its public space
as confirmation message.
A snapshot of the result of the signature procedure
on Twitter is illustrated in Figure 2, where the tweet
posted by the signer and that posted by the university
are reported.
Consider now the procedure used to check the va-
lidity of a signature. When a user has to check the sig-
nature on a document D, the digest h(D) is computed.
Then, the hashtag #h(D) is searched on Twitter.
If no tweet is found, then the document is consid-
ered never signed. If a pair of equal tweets hsignature
message, confirmation messagei, the first posted by
a user S, the second posted by @univ is found, and
if @univ follows the Twitter account of S, then D is
considered signed by S. Finally, if a signature mes-
sage without the corresponding confirmation message
is found or if a confirmation message without the cor-
responding signature message is found, the verifica-
tion procedure notifies a possible attack and the type,
according to the security analysis provided in Section
Finally, consider the revocation procedure. When
it is necessary to revoke the permission of signature to
a student or an employee, then the following relation
from @univ to the Twitter account of such a person
is removed. Then, @univ will be not notified about
any tweet posted by this person and no confirmation
message will be produced. Consequently, if this per-
son tries to sign a document, the signature verification
procedure will fail (no confirmation message for this
person is found).
Finally, it is worth noting that the use of Twitter as
social network producesan interesting side effect, that
is the timestamp of the signature generation. Observe
that this is a feature usually not required in digital sig-
nature, and typically provided not for free by a trusted
third party. This is another characteristic that makes
our proposal more interesting also from the cost point
of view.
The need of guaranteeing authenticity and integrity
of digital documents is high in many application con-
texts, such as e-commerce and e-government. The
tool typically used for this purpose relies on digi-
tal signature, which provides high security standards.
A New Approach for Electronic Signature
Figure 2: An instantiation of the signature procedure.
However, due to some drawbacks of digital-signature-
based solutions, the request of more simple and cheap
solutions is growing.
The concept of electronic signature has been intro-
duced in many country to simplify and make more ef-
fective the process of dematerialization of documents
and transactions, both in the public sector and in busi-
In this paper, we presented a new form of elec-
tronic signature which overcomes the drawbacks of
digital signature. Our approach is based on the use
of social networks to share the information necessary
to sign and verify a signature. Thus, a first advantage
is related to the user-friendliness, as people are well
disposed to work in an environment they well know
(i.e., social network). The fact that, in our solution no
private key or PKI infrastructure has to be managed,
is a great advantage. From this point of view, our pro-
posal overcomes other solutions such as those using
PKI technology within OpenSSL.
The security analysis of the approach showed that
it is able to guarantee authenticity, integrity and non-
repudiation, and to be resistant against a large number
of attacks, which are also detected (Buccafurri et al.,
2014b; Buccafurri et al., 2015).
The effectiveness of our proposal has been shown
by describing an instantiation of our generic approach
in a scenario related to an university, where the social
network considered is Twitter.
This work has been partially supported by the
TENACE PRIN Project (n. 20103P34XC) funded
by the Italian Ministry of Education, University and
Research and by the Program “Programma Operativo
Nazionale Ricerca e Competitivit`a” 2007-2013, Dis-
tretto Tecnologico CyberSecurity funded by the Ital-
ian Ministry of Education, University and Research.
Alsaid, A. and Mitchell, C. J. (2005). Dynamic content at-
tacks on digital signatures. Information Management
& Computer Security, 13(4):328–336.
Ateniese, G., Blundo, C., De Santis, A., and Stinson, D. R.
(1996). Constructions and bounds for visual cryptog-
raphy. In Automata, Languages and Programming,
pages 416–428. Springer.
Berta, I. Z., Butty´an, L., and Vajda, I. (2004). Mitigating the
untrusted terminal problem using conditional signa-
tures. In Information Technology: Coding and Com-
ICISSP 2016 - 2nd International Conference on Information Systems Security and Privacy
puting, 2004. Proceedings. ITCC 2004. International
Conference on, volume 1, pages 12–16. IEEE.
Berta, I. Z. and Vajda, I. (2003). Documents from malicious
terminals. In Microtechnologies for the New Millen-
nium 2003, pages 325–336. International Society for
Optics and Photonics.
Buccafurri, F., Fotia, L., and Lax, G. (2014a). Social signa-
ture: Signing by tweeting. In Electronic Government
and the Information Systems Perspective, pages 1–14.
Buccafurri, F., Lax, G., Nicolazzo, S., and Nocera, A.
(2014b). A Privacy-Preserving Solution for Tracking
People in Critical Environments. In Proc. of the In-
ternational Workshop on Computers, Software & Ap-
plications (COMPSAC’14), pages 146–151, V ¨aster˙as,
Sweden. IEEE Computer Society.
Buccafurri, F., Lax, G., Nicolazzo, S., and Nocera, A.
(2014c). A model to support multi-social-network
applications. In On the Move to Meaningful Inter-
net Systems: OTM 2014 Conferences, pages 639–656.
Buccafurri, F., Lax, G., Nicolazzo, S., and Nocera, A.
(2015). Accountability-preserving anonymous deliv-
ery of cloud services. In Trust, Privacy and Security
in Digital Business, pages 124–135. Springer.
Buccafurri, F., Lax, G., Nicolazzo, S., Nocera, A., and
Ursino, D. (2013). Measuring betweenness centrality
in social internetworking scenarios. In On the Move to
Meaningful Internet Systems: OTM 2013 Workshops,
pages 666–673. Springer.
Buccafurri, F., Lax, G., Nicolazzo, S., Nocera, A., and
Ursino, D. (2014d). Driving global team formation
in social networks to obtain diversity. In Web Engi-
neering, pages 410–419. Springer.
Carter, J. L. and Wegman, M. N. (1977). Universal classes
of hash functions. In Proceedings of the ninth annual
ACM symposium on Theory of computing, pages 106–
112. ACM.
Chaum, D. and Roijakkers, S. (1991). Unconditionally-
secure digital signatures. In Advances in Cryptology-
CRYPT090, pages 206–214. Springer.
Chor, B., Goldwasser, S., Micali, S., and Awerbuch, B.
(1985). Verifiable secret sharing and achieving simul-
taneity in the presence of faults. In Foundations of
Computer Science, 1985., 26th Annual Symposium on,
pages 383–395. IEEE.
Clarke, D., Gassend, B., Kotwal, T., Burnside, M.,
Van Dijk, M., Devadas, S., and Rivest, R. (2002).
The untrusted computer problem and camera-based
authentication. In Pervasive Computing, pages 114–
124. Springer.
Gilbert, E. N., MacWilliams, F. J., and Sloane, N. J. (1974).
Codes which detect deception. Bell System Technical
Journal, 53(3):405–424.
He, D., Chan, S.-C., Zhang, Y., Guizani, M., Chen, C.,
and Bu, J. (2014). An enhanced public key infras-
tructure to secure smart grid wireless communication
networks. Network, IEEE, 28(1):10–16.
Kim, D., Jeon, Y., and Kim, J. (2014). A secure channel
establishment method on a hardware security module.
In Information and Communication Technology Con-
vergence (ICTC), 2014 International Conference on,
pages 555–556. IEEE.
Ko´scielny, C., Kurkowski, M., and Srebrny, M. (2013).
Public key infrastructure. In Modern Cryptography
Primer, pages 175–191. Springer.
Lax, G., Buccafurri, F., and Caminiti, G. (2015). Digi-
tal document signing: Vulnerabilities and solutions.
Information Security Journal: A Global Perspective,
pages 1–14.
Lee, B. and Kim, K. (2002). Fair exchange of digital sig-
natures using conditional signature. In Symposium on
Cryptography and Information Security, pages 179–
Matsumoto, T. (1998). Human–computer cryptography: An
attempt. Journal of Computer Security, 6(3):129–149.
Mavrovouniotis, S. and Ganley, M. (2014). Hardware se-
curity modules. In Secure Smart Embedded Devices,
Platforms and Applications, pages 383–405. Springer.
Naor, M. and Pinkas, B. (1997). Visual authentica-
tion and identification. In Advances in Cryptology-
CRYPTO’97, pages 322–336. Springer.
Naor, M. and Shamir, A. (1995). Visual cryptography.
In Advances in CryptologyEUROCRYPT’94, pages 1–
12. Springer.
Nocera, A. and Ursino, D. (2012). PHIS: a system for scout-
ing potential hubs and for favoring their “growth” in
a Social Internetworking Scenario. Knowledge-Based
Systems, 36:288–299. Elsevier.
Rabin, T. (1994). Robust sharing of secrets when the dealer
is honest or cheating. Journal of the ACM (JACM),
Rabin, T. and Ben-Or, M. (1989). Verifiable secret sharing
and multiparty protocols with honest majority. In Pro-
ceedings of the twenty-first annual ACM symposium
on Theory of computing, pages 73–85. ACM.
Shaji, S. et al. (2014). Anti phishing approach using visual
cryptography and iris recognition. IJRCCT, 3(3):088–
Sharma, A. and Srivastava, D. K. (2014). A comprehen-
sive view on encryption techniques of visual cryptog-
raphy? International Journal of Recent Research and
Review, 7(2).
Simmons, G. J. (1985). Authentication theory/coding the-
ory. In Advances in Cryptology, pages 411–431.
Sustek, L. (2011). Hardware security module. In Encyclo-
pedia of Cryptography and Security, pages 535–538.
A New Approach for Electronic Signature