Security Analysis of a Single Sign-On Mechanism For Distributed Computer
Networks
ABSTRACT:
The Single sign-on (SSO) is a new authentication
mechanism that enables a legal user with a single credential to be
authenticated by multiple service providers in a distributed computer network.
Recently, Chang and Lee proposed a new SSO scheme and claimed its security by
providing well-organized security arguments. In this paper, however, we
demonstrative that their scheme is actually insecure as it fails to meet
credential privacy and soundness of authentication. Specifically, we present
two impersonation attacks. The first attack allows a malicious service
provider, who has successfully communicated with a legal user twice, to recover
the user’s credential and then to impersonate the user to access resources and
services offered by other service providers. In another attack, an outsider
without any credential may be able to enjoy network services freely by
impersonating any legal user or a nonexistent user. We identify the flaws in
their security arguments to explain why attacks are possible against their SSO
scheme. Our attacks also apply to another SSO scheme proposed by Hsu and
Chuang, which inspired the design of the Chang–Lee scheme. Moreover, by
employing an efficient verifiable encryption of RSA signatures proposed by
Ateniese, we propose an improvement for repairing the Chang–Lee scheme. We
promote the formal study of the soundness of authentication as one open
problem.
EXISTING SYSTEM:
The
other side, it is usually not practical by asking one user to maintain distinct
pairs of identity and password for different service providers, since this
could increase the workload of both users and service providers as well as the
communication overhead of networks. That, after obtaining a credential from a
trusted authority for a short period each legal user’s authentication agent can
use this single credential to complete authentication on behalf of the user and
then access multiple service providers. Intuitively, an SSO scheme should meet
at least three basic security requirements, enforceability, credential
privacy, and soundness.
Enforceability demands that, except the trusted authority, even a collusion of
users and service providers are not able to forge a valid credential for a new
user. Credential privacy guarantees that colluded dishonest service providers
should not be able to fully recover a user’s credential and then impersonate
the user to log in to other service providers. Soundness means that an
unregistered user without a credential should not be able to access the
services offered by service providers.
DISADVANTAGES OF EXISTING SYSTEM:
·
Actually
an SSO scheme, has two weaknesses an outsider can forge a valid credential by
mounting a credential forging attack since the scheme employed naïve RSA
signature without using any hash function to issue a credential for any random
identity.
·
Their
scheme is suitable for mobile devices due to its high efficiency in computation
and communication.
PROPOSED SYSTEM
The
first attack, the “credential recovering attack” compromises the credential
privacy in the scheme as a malicious service provider is able to recover the
credential of a legal user. The other attack, an “impersonation attack without
credentials,” demonstrates how an outside attacker may be able to freely make
use of resources and services offered by service providers, since the attacker
can successfully impersonate a legal user without holding a valid credential
and thus violate the requirement of soundness for an SSO scheme. In real life,
these attacks may put both users and service providers at high risk In fact;
this is a traditional as well as prudential way to deal with trustworthiness,
since we cannot simply assume that beside the trusted authority, all service
providers are also trusted. The basic reason is that assuming the existence of
a trusted party is the strongest supposition in cryptography but it is usually
very costly to develop and maintain. In particular defined collusion
impersonation attacks as a way to capture the scenarios in which malicious
service providers may recover a user’s credential and then impersonate the user
to login to other service providers. It is easy to see that the above
credential recovery attack is simply a special case of collusion impersonation
attack where a single malicious service provider can recover a user’s
credential. It must be emphasized that impersonation attacks without valid
credentials seriously violate the security of SSO schemes as it allows attackers
to be successfully authenticated without first obtaining a valid credential
from the trusted authority after registration.
ADVANTAGES OF PROPOSED SYSTEM:
·
The
authors claimed to be able to: “prove that and are able to authenticate each
other using our protocol.” but they provided no argument to show why each party
could not be impersonated by an attacker. Second, the authors did discuss
informally why their scheme could withstand impersonation attacks.
·
The
authors did not give details to show how the BAN logic can be used to prove
that their scheme guarantees mutual authentication.
·
In
other words, it means that in an SSO scheme suffering these attacks there are
alternatives which enable passing through authentication without credentials.
MODULES:
ü
User Identification Phase
ü Attacks against the Chang–Lee Scheme
ü
Recovering Attack
ü Non-interactive zero-knowledge(NZK)
ü
Security Analysis
MODULE DESCRIPTION:
User Identification
Phase
To access the resources of service provider, user needs to go through
the authentication protocol specified. Here, and are random integers chosen by
and, respectively; and are three random nonces; and denotes a symmetric key encryption
scheme which is used to protect the confidentiality of user’s identity.
Attacks against the Chang–Lee Scheme
The Chang–Lee scheme is actually not a secure SSO scheme because there
are two potential effective and concrete impersonation attacks. The first
attack, the “credential recovering attack” compromises the credential privacy
in the Chang–Lee scheme as a malicious service provider is able to recover the
credential of a legal user. The other attack, an “impersonation attack without
credentials,” demonstrates how an outside attacker may be able to freely make
use of resources and services offered by service providers, since the attacker
can successfully impersonate a legal user without holding a valid credential
and thus violate the requirement of soundness for an SSO scheme. In real life,
these attacks may put both users and service providers at high risk.
Recovering Attack
The
malicious and then mount the above attack.
On the one hand, the Chang–Lee SSO scheme specifies that is the trusted
party. So, this implies that service providers are not trusted parties and that
they could be malicious. By agreeing with, when they said that “the Wu–Hsu’s
modified version cold not protect the user’s token against a malicious service
provider, the work also implicitly agrees that there is the potential for
attacks from malicious service providers against SSO schemes. Moreover, if all
service providers are assumed to be trusted, to identify him/her user can
simply encrypt his/her credential under the RSA public key of service provider.
Then, can easily decrypt this cipher text to get ’s credential and verify its
validity by checking if it is a correct signature issued by . In fact, such a
straightforward scheme with strong assumption is much simpler, more efficient
and has better security, at least against this type of attack.
Non-interactive zero-knowledge (NZK)
The
basic idea of VES is that Alice who has a key pair of signature scheme signs a
given message and encrypts the resulting signature under the trusted party’s
public key, and uses a non-interactive zero-knowledge (NZK) proof to convince Bob that she has signed the
message and the trusted party can recover the signature from the cipher text.
After validating the proof, Bob can send his signature for the same message to
Alice. For the purpose of fair exchange, Alice should send her signature in
plaintext back to Bob after accepting Bob’s signature.
Security Analysis
The
security of the improved SSO scheme by focusing on the security of the user
authentication part, especially soundness and credential privacy due to two
reasons. On the one hand, the unforgeability of the credential is guaranteed by
the unforgeability of RSA signatures, and the security of service provider
authentication is ensured by the unforgeability of the secure signature scheme
chosen by each service provider.
SYSTEM CONFIGURATION:-
HARDWARE CONFIGURATION:-
ü
Processor -Pentium –III
ü Speed - 1.1 Ghz
ü RAM - 256 MB(min)
ü Hard
Disk - 20 GB
ü Floppy
Drive - 1.44 MB
ü Key
Board - Standard Windows Keyboard
ü Mouse - Two or Three Button Mouse
ü Monitor - SVGA
SOFTWARE CONFIGURATION:-
v Operating System :
Windows XP /7
v Programming Language : JAVA
v Java Version : JDK 1.6 & above.
REFERENCE:
Guilin
Wang, Jiangshan Yu, and Qi Xie, “Security Analysis of a
Single Sign-On Mechanism for Distributed Computer Networks”, IEEE TRANSACTIONS
ON INDUSTRIAL INFORMATICS, VOL. 9, NO. 1, FEBRUARY 2013.
