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SIMPLE AUTHENTICATION AND SECURITY LAYER INCORPORATING EXTENSIBLE AUTHENTICATION PROTOCOL

Authors:
SIMPLE AUTHENTICATION AND SECURITY LAYER INCORPORATING
EXTENSIBLE AUTHENTICATION PROTOCOL
BY
MYUNG-SUN KIM
B.S., University of New Hampshire, 2005
B.A., University of New Hampshire, 2005
THESIS
Submitted to the University of New Hampshire
in Partial Fulfillment of
the Requirements for the Degree of
Master of Science
In
Computer Science
May, 2007
This thesis has been examined and approved.
___________________________________________
Thesis Director, Dr. Radim Bartoš
Associate Professor of Computer Science
___________________________________________
Scott A. Valcourt
Research Project Manager of Computer Science
___________________________________________
Dr. Ted M. Sparr
Professor of Computer Science
____________________________________
Date
DEDICATION
To my father, Young-Joo Kim
to my mother, Ae-Ja Kim
to my sister, Min-Sun Kim
to my brother-in-law, Jong-Seog Jung
to my nephew, Sae-Jun Jung
and to my wife, Sissy Kim.
iii
ACKNOWLEDGEMENT
I would like to express my appreciation to all those who made it possible for me
to finish my master thesis here at UNH.
I would like to thank my advisor, Dr. Radim Bartoš, and my Research Project
Manager, Mr. Scott A. Valcourt for their support, time, and helpful feedback during my
master studies as well as my undergraduate studies. Their patience and their guidance
throughout my whole master thesis gave me a great experience here at UNH. I also wish
to thank my thesis committee, Dr. Ted M. Sparr, for his time and consideration.
Lastly, I would like to express my gratitude to the Meetinghouse Data
Communication, Inc. (now part of Cisco Systems, Inc.) and the National Institute of
Justice; Datacasting Project for Project54
TM
, for funding my graduate work.
iv
TABLE OF CONTENTS
DEDICATION...................................................................................................................iii
ACKNOWLEDGEMENTS...............................................................................................iv
LIST OF TABLES.............................................................................................................vii
LIST OF FIGURES.......................................................................................................... viii
ABSTRACT...................................................................................................................... ix
1 INTRODUCTION......................................................................................................1
2 BACKGROUND........................................................................................................ 5
2.1 Terminology.......................................................................................................5
2.2 Simple Authentication and Security Layer (SASL)...........................................7
2.3 Extensible Authentication Protocol (EAP)........................................................ 9
2.4 EAP-Pre-Shared Key (EAP-PSK)................................................................... 12
2.5 EAP-Transport Layer Security-PSK (EAP-TLS-PSK)................................... 12
2.6 Motivations and Goals..................................................................................... 13
3 EXTENSIBLE AUTHENTICATION PROTOCOL – ADVANCED
ENCRYPTION STANDARD – PRE-SHARED KEY (EAP-AES-PSK)............15
3.1 Approach........................................................................................................16
3.2 EAP-AES-PSK Message Flows and Packet Format......................................18
3.3 Features of EAP-AES-PSK............................................................................24
3.4 EAP-AES-PSK Supporting Aspects.............................................................. 25
v
3.4.1 Fragmentation................................................................................ 25
3.4.2 Channel Binding............................................................................ 26
3.4.3 Fast Reconnection..........................................................................26
3.4.4 Key Strength.................................................................................. 27
3.4.5 Number of Message Exchanges.....................................................28
3.4.6 Tunnel Support...............................................................................28
3.5 Protections against Security Risks................................................................. 28
3.5.1 Dictionary Attack...........................................................................29
3.5.2 Replay Attack.................................................................................30
3.5.3 Man-In-The-Middle (MITM) Attack.............................................30
3.5.4 Re-Keying...................................................................................... 32
3.5.5 Data Encryption............................................................................. 32
4 VERIFICATIONS................................................................................................... 33
4.1 Outcomes........................................................................................................ 33
4.2 Evaluation....................................................................................................... 34
4.2.1 Verification of Functionality of a SASL Application
incorporating EAP......................................................................... 34
4.2.2 Performance Evaluation................................................................40
5 CONCLUSION....................................................................................................... 47
BIBLIOGRAPHY........................................................................................................... 49
APPENDICES.................................................................................................................. 51
APPENDIX A ABBREVIATION AND ACRONYMS.............................................. 52
APPENDIX B EXPERIMENTS/USER GUIDES.......................................................53
B.1 Cyrus Installation........................................................................................... 53
B.2 Cyrus usage of ANONYMOUS mechanism with file transfer......................54
B.3 Cyrus Password Setup (using sasldb)............................................................ 54
B.4 Add Mechanism Plugins................................................................................ 55
vi
LIST OF TABLES
2.1 Terminology...................................................................................................................5
3.1 Features of Pre-Shared Key Methods.......................................................................... 24
4.1 Configuration of EAP-AES-PSK.................................................................................35
4.2 95% Confidence Level Authentication Time for each Method.................................. 42
4.3 95% Confidence Level Completion Time in the Controlled Environment................. 46
4.4 95% Confidence Level Completion Time in the Un-Controlled Environment........... 46
vii
LIST OF FIGURES
1-1 SASL Incorporating EAP Abstract Layer..................................................................4
2-1 SASL Abstract Layer..................................................................................................7
2-2 Authentication Protocols ............................................................................................9
2-3 (a) EAP Message Exchange without AAA, (b) EAP Message Exchange................11
2-4 EAP Packet Format................................................................................................... 12
3-1 Key Setup Algorithm in EAP-AES-PSK.................................................................. 17
3-2 Key Derive Algorithm in EAP-AES-PSK.................................................................17
3-3 EAP-AES-PSK Packet Format..................................................................................19
3-4 EAP-AES-PSK Authentication Message Exchanges................................................ 20
3-5 Dictionary Attack..................................................................................................29
3-6 Man-In-The-Middle (MITM) Attack........................................................................31
4-1 Authentication Time for each Method......................................................................42
4-2 (a) Server Completion Time in the Controlled Environment,
(b) Client Completion Time in the Controlled Environment......................................44
4-3 (a) Server Completion Time in the Un-Controlled Environment,
(b) Client Completion Time in the Un-Controlled Environment................................45
viii
ABSTRACT
SIMPLE AUTHENTICATION AND SECURITY LAYER
INCORPORATING EXTENSIBLE AUTHENTICATION PROTOCOL
by
Myung-Sun Kim
University of New Hampshire, May, 2007
There are many methods that support user authentication and access control,
important roles in the establishment of secure communication. Particularly, we examine
Simple Authentication and Security Layer (SASL) and Extensible Authentication
Protocol (EAP) and propose EAP-Advanced Encryption Standard-Pre-Shared-Key (EAP-
AES-PSK). SASL is an authentication framework in connection-oriented protocols. EAP
is an authentication framework providing multiple authentication methods. SASL is
vulnerable to the dictionary attack, replay attack, and Man-In-The-Middle attack as well
as the re-keying issue. We propose to incorporate EAP into SASL to enhance the security
of SASL and to provide a pathway for easy incorporation of future EAP enhancements
into SASL. Standalone EAP still faces some common attacks. We propose EAP-AES-
PSK, a new EAP method, to provide strong authentication and we implement this method
on the Cyrus SASL implementation: one of the publicly available SASL
implementations. This project is evaluated through the verification of functionality of a
SASL application incorporating EAP. Further, we argue how the common security risks
associated with SASL are addressed, and we complete a performance evaluation of the
new method incorporated into SASL.
ix
CHAPTER 1
INTRODUCTION
Authentication and access control of users are important functions in the
establishment of secure communication. Both senders and receivers should be able to
verify the identity the other party. However, successful authentication does not always
occur over insecure network connections. One of the commonly used authentication
approaches is to authenticate via user identification (ID) and user password, or via host IP
address. These methods are subject to the risks of insecure communication when an
intruder gains physical access of the communication medium between users and hosts,
such as what occurs in the dictionary attack, replay attack, and Man-In-The-Middle
(MITM) attack. Therefore, software developers must consider network security when
they design and develop network enabled software programs.
Simple Authentication and Secure Layer (SASL) [17] protocol provides a
straightforward solution for the software developer without a deep understanding of
network security. SASL provides an authentication framework in connection-oriented
protocols and a secure data transportation mechanism between a server and a client that is
detached from existing application protocols. The SASL framework allows either new
applications to reuse existing authentication protocol mechanisms or allows old
applications to use new authentication protocols without requiring any modifications of
1
the SASL library [17]. SASL has been incorporated into a few widely used protocols
such as the Lightweight Directory Access Protocol (LDAP), Post Office Protocol 3
(POP3), the Internet Message Access Protocol (IMAP), and Telnet to enable pluggable
authentication [23]. Currently, there are two publicly available SASL libraries: the Cyrus
SASL library from Carnegie Mellon University and the GNU SASL library.
Even though SASL provides a standardized framework for an application
supporting multiple authentication methods, the SASL authentication methods are
vulnerable to many common attacks, such as dictionary attack, replay attack, and Man-
In-The-Middle (MITM) attack, in addition to insecure data transportation. Therefore, we
propose a method to protect against these attacks by integrating Extensible
Authentication Protocol (EAP) [2] into SASL.
EAP is an authentication framework providing multiple authentication methods.
Since EAP is not a specific authentication mechanism, the exact authentication type is
chosen by negotiating between a peer and an authenticator. EAP runs over data link
layers where the Internet Protocol (IP) is not required, e.g., Point-to-Point Protocol (PPP)
[21] or Institute of Electrical and Electronics Engineers (IEEE) 802 standard protocols.
Currently, there exist over 40 different EAP methods [2] to provide strong authentication
services and secure data transmission.
This document outlines the benefits and the problems in standalone SASL,
followed by the advantages we will gain by combining EAP and SASL. Further, we
present details on how to integrate EAP into SASL, so that SASL incorporating EAP
addresses the existing weaknesses in SASL. This work builds upon a new EAP method,
EAP - Advanced Encryption Standard - Pre-Shared Key (EAP-AES-PSK) that is an
2
updated version of EAP - Transport Layer Security-Pre - Shared-Key (EAP-TLS-PSK)
[14].
Cyrus SASL implementation, randomly chosen for this project, incorporates
several types of plugins: mechanism plugins, user canonization plugins, and auxiliary
property plugins. Mechanism plugins are for authentication methods. User canonization
plugins are used to differ the ways of canonizing authentication and authorization IDs.
Auxiliary property plugins enable auxiliary properties about user credentials to be
accessible, such as Authentication, Authorization and Accounting (AAA) services [18].
This project proposes to incorporate EAP into SASL to enhance security of SASL
and to provide a pathway for easy incorporation of future EAP enhancements into SASL
as well as to update and to implement EAP-AES-PSK. SASL incorporating EAP
typically works by placing the EAP interface into the SASL library. The EAP interface
not only bridges between the SASL library and existing SASL authentication methods,
but also links the SASL library and future EAP authentication methods.
Figure 1-1 illustrates the architecture of SASL incorporating EAP including
where the EAP interface is located in the SASL library directory and how the EAP
interface connects SASL with legacy and future authentication methods. A more detailed
explanation is presented in Chapter 2.
3
Application:
IMAP, SMTP, POP, or
LDAP
Application:
IMAP, SMTP, POP, or
LDAP
DBs:
SASLDB, LDAP, or
SQL
Mechanism:
ANONYMOUS,
LOGIN, PLAIN,
DIGEST-MD5,
CRAM-MD5, or
EXTERNAL
Plugins
Plugins
Client
Server
DBs:
SASLDB, LDAP, or
SQL
New Mechanism
i.e. EAP-PSK
Mechanism:
ANONYMOUS,
LOGIN, PLAIN,
DIGEST-MD5,
CRAM-MD5, or
EXTERNAL
New Mechanism
i.e. EAP-PSK
EAP
Network
TCP connection
EAP
SASL Abstraction SASL Abstraction
Figure 1-1: SASL Incorporating EAP Abstract Layer
4
CHAPTER 2
BACKGROUND
We present background details of Simple Authentication and Security Layer
(SASL), Extensible Authentication Protocol (EAP), EAP-Pre-Shared Key (EAP-PSK),
and EAP-Transport Layer Security-PSK (EAP-TLS-PSK).
2.1Terminology
This document frequently uses the following terms:
Table 2-1: Terminology
AAA server The entity that provides Authentication, Authorization,
and Accounting services to an authenticator. In this
document, the terms "AAA server" and "authentication
server" are used interchangeably. The authentication
server is typically a Remote Authentication Dial-In User
Service (RADIUS) server.
Authentication Key (AK) A static long-lived key, derived from the Pre-Shared Key
(PSK), is to mutually authenticate the EAP peer and the
EAP server [2].
Authentication The process to verify the user identity in a
communication such as requiring to log in.
Client The end of the link that responds to the authenticator.
This end is known as the supplicant in [12] and the peer
in [2]. In this document, the terms "peer", "supplicant",
and “client” are used interchangeably.
5
Table 2-1 Continued
Extended Master Session
Key (EMSK)
Additional keying material derived between the EAP
client and server that is exported by the EAP method. The
EMSK is at least 64 octets in length. The EMSK is not
shared with the authenticator or any other third party. The
EMSK is reserved for future uses that are not yet defined.
Key Derivation Key
(KDK)
A static long-lived key, derived from the Pre-Shared Key
(PSK), is to derive session keys [2].
Master Session Key
(MSK)
Master Keying material that is derived between the EAP
peer and server and exported by the EAP method. The
MSK is at least 64 octets in length. In existing
implementations, an AAA server acting as an EAP server
transports the MSK to the authenticator.
Nonce A number used once, such as a random number.
Pre-Shared Key (PSK) A key in symmetric cryptography that is installed/sent to
the opposite side of the connection in advance, or that is
distributed by third party.
Server The entity that terminates the EAP authentication method
with the peer. In the case where no backend
authentication server is used, the EAP server is part of
the authenticator. In the case where the authenticator
operates in pass-through mode, the EAP server is located
on the backend authentication server.
Successful Authentication In this document, "successful authentication" is involved
both authentication and authorization; even though the
peer may pass authentication to the server, the peer may
not have access to the server due to policy reasons [2].
For instance, the peer has a basic services right on a
server and the peer tries to access a premium services on
the server. The peer successfully authenticates to the
authenticator, but is not able to access to the server.
6
2.2Simple Authentication and Security Layer (SASL)
SASL is a framework to incorporate authentication in connection-oriented
protocols and secure data transportation between a server and client that is detached from
application protocols.
The SASL framework allows either new applications to reuse existing
authentication protocol mechanisms, or allows old applications to use new authentication
protocols without requiring any modifications to the SASL library [17].
Application:
IMAP, SMTP, POP, or
LDAP
Application:
IMAP, SMTP, POP, or
LDAP
SASL Abstraction SASL Abstraction
DBs:
SASLDB, LDAP, or
SQL
Mechanism:
ANONYMOUS,
LOGIN, PLAIN,
DIGEST-MD5,
CRAM-MD5, or
EXTERNAL
Plugins Plugins
Client
Server
DBs:
SASLDB, LDAP, or
SQL
Mechanism:
ANONYMOUS,
LOGIN, PLAIN,
DIGEST-MD5,
CRAM-MD5, or
EXTERNAL
Network
TCP connection
Figure 2-1: SASL Abstract Layer
7
Figure 2-1 illustrates the SASL abstract layer. Both client and server sides in the
figure have three parts: an application, the SASL abstraction, and various plugins. The
application is generally some connection-oriented protocol, such as Internet Message
Access Protocol (IMAP), Simple Mail Transfer Protocol (SMTP), Post Office Protocol
(POP), or Lightweight Directory Access Protocol (LDAP). Plugins contain database
system and authentication protocol mechanisms. The SASL abstraction in the client and
the server communicate to authenticate and authorize the connection, while the SASL
abstraction monitors its application and plugins.
Both client and server sides in Figure 2-1 are symmetric; however, it is not
required. For example, in the client side, database system SASL is not necessary because
only the server side maintains user credential information within database systems. The
client does not need to have all of the authentication methods that the server has available
or vice-versa. When a client has only ANONYMOUS SASL method [24] that does not
require authentication for guest access, SASL works fine if a server provides the
ANONYMOUS SASL method with other authentication methods. However, if the server
does not support the ANONYMOUS SASL method, the server will not authenticate the
client. In order to access a server, a client must have one of the authentication methods
supported by the server.
GNU and Cyrus SASL libraries support the applications: LDAP, IMAP, SMTP,
and POP, and provide several authentication methods such as ANONYMOUS (for
unauthenticated guest access), PLAIN (a simple clear text password mechanism), LOGIN
(a simple password mechanism), CRAM-MD5 (a simple challenge-response scheme
8
based on HMAC-MD5 [7]), and EXTERNAL (for where authentication is implicit in the
context).
Although SASL has many advantages, standalone SASL is vulnerable to many
common attacks and insecure data transportation, in addition to re-keying issues, because
many existing SASL mechanisms are vulnerable to these attacks and do not provide
secure data encryption. Many of these attacks are addressed further in this chapter.
2.3Extensible Authentication Protocol (EAP)
EAP was originally developed for the extensible usage of authentication protocols
defined in Point-to-Point Protocol (PPP) [21], such as Password Authentication Protocol
(PAP) [RFC 1334] and Challenge Handshake Authentication Protocol (CHAP) [22].
Figure 2-2 describes authentication protocols hierarchy [4].
Authentication Protocols
Password Authentication Protocol
(PAP)
Challenge-Handshake
Authentication Protocol (CHAP)
Extensible Authentication Protocol
(EAP)
MD5 - Challenge
One Time Password (OTP)
Generic Token Card (GTC)
....
....
Figure 2-2: Authentication Protocols
9
EAP is an authentication framework providing multiple authentication methods.
Since EAP is not a specific authentication mechanism, the exact authentication type is
chosen by negotiation between a peer and an authenticator. EAP provides its own support
for avoiding duplication and retransmission, but not fragmentation. However, standalone
EAP is not secure enough to authenticate and has various vulnerabilities [2].
Since all traffic within EAP methods is exposed to attackers, user identities are
visible. EAP is vulnerable to replaying packets, dictionary attack, disrupting negotiation,
as well as other vulnerabilities described in [2]. Even though standalone EAP methods
are not acceptable over wireless networks or Virtual Private Networks (VPNs) due to
those attacks, EAP is widely used in wired networks and Point-to-Point connections
because EAP is an authentication framework, not a specific authentication mechanism.
EAP provides a negotiation of the desired authentication mechanism [9]. A stronger
authentication mechanism protects against the collection of vulnerable attacks while
standalone EAP does not.
Figure 2-3 demonstrates an EAP message exchange. In EAP message exchanges,
an EAP server requests user identity information from an EAP client and the client
responds with the requested information back to the server. After the server obtains user
identity information, more messages will be exchanged depending on the authentication
process. The EAP server finally sends a message indicating whether the user
authentication succeeds or fails.
In Figure 2-3 (b) including Authentication, Authorization, and Accounting
(AAA), the authentication server provides AAA services designed for ease in tracking
usage for billing and network statistics purposes. Authentication server clients transfer
10
user credentials to the authentication server and the authentication server authenticates
the user based on the provided credentials. The authentication server can be viewed as a
kind of database and controller for usage billing and for network traffic management.
However, this project mainly focuses on SASL and EAP, not on AAA services that the
authentication server provides. Figure 2-3 (a) illustrates the EAP message exchange
without AAA.
Client
Server
EAP-Request/Identity
EAP-Response/Identity
EAP-Success or Failure
Multiple Message Sequences Depending
on the Authentication Process
(a)
Peer
Authenticator
Authentication Server
(AAA)
EAP-Request/Identity
EAP-Response/Identity
EAP-Success or Failure
Multiple Message Sequences
Depending on the Authentication
Process
Other Systems for Authentication
such as RADIUS
(b)
Figure 2-3: (a) EAP Message Exchange without AAA,
(b) EAP Message Exchange
11
Figure 2-4 describes an EAP packet format.
Figure 2-4: EAP Packet Format [2]
2.4Extensible Authentication Protocol – Pre-Shared Key (EAP-PSK)
A Pre-Shared Key EAP method (EAP-PSK) is one of the EAP methods that use
PSK for mutual authentication and session key derivation. While EAP is a framework to
authenticate, EAP-PSK is an actual authentication mechanism that utilizes PSK upon the
EAP framework. EAP-PSK normally exchanges four messages in the authentication
process between a client and a server. Once the authentication is successful, EAP-PSK
provides a protected communication channel [5].
2.5Extensible Authentication Protocol Transport Layer Security
Pre-Shared Key (EAP-TLS-PSK)
EAP-TLS-PSK [14] is a new authentication method, EAP-PSK with TLS [6]
tunneling support, as an EAP protocol that extends EAP-PSK, one of the authentication
protocols based on pre-shared keys. EAP-TLS-PSK uses secure tunnel establishment by
12
TLS handshake to exchange authentication-related information between a client and a
server, while EAP-PSK simply uses pre-shared keys to mutually authenticate.
Authentication not based on certificates allows a reduced cost of management with fewer
message exchanges between client and server.
EAP-TLS-PSK [14] consists of two primary phases: Transport Layer Security
(TLS) Handshake Phase and TLS Tunnel Phase. The TLS Handshake Phase is similar to
the EAP-TLS [8] handshake Phase. Rather than using the EAP server to generate a
required certificate, the process uses the EAP-PSK scheme to authenticate mutually and
to establish the secure protected channel necessary for further connectivity.
In the TLS Tunnel Phase, further authentication takes place in the initially-
established secure tunnel from the TLS Handshake Phase. EAP-PSK with tunneling
employs the EAP-Type Length Value (EAP-TLV) method [11], allowing richer
communication between client and server, to further authenticate EAP identity. At the
conclusion of the TLS Tunnel Phase, MSK is derived using the TLS Pseudo Random
Function (PRF) [8] from inner authentications that are mixed with the inner secret Key-
Derivation Key (KDK) [5] from the TLS Handshake Phase and the TLS client and server
random numbers to protect subsequent data.
2.6Motivations and Goals
This project merges two technologies, SASL and EAP, to make the network more
secure and introduces EAP-AES-PSK to provide strong authentication that is a new EAP
method and will be built on SASL.
13
SASL provides key security services to a number of application protocols such as
e-mail protocols, so that software engineers can have a handy security tool. Software
developers focus on only their application level, not communication security issues.
Currently publicly available SASL libraries are the Cyrus SASL library by Carnegie
Mellon University and the GNU SASL library. Both SASL libraries are used in IMAP,
LDAP, POP, and SMTP to provide secure authentication.
EAP is widely being deployed in environments such as wireless networks and
used over the Internet to support multiple authentication methods, such as token cards,
one-time passwords, Kerberos (a network authentication protocol using secret-key
cryptography) [13], and certificates. EAP-AES-PSK, described in Chapter 3, is a new
strong authentication method that will be built on the SASL implementation.
SASL incorporating EAP typically works by locating the EAP interface in SASL
plugins. The EAP interface not only bridges between the SASL library and existing
SASL authentication methods, but also links the SASL library and future EAP
authentication methods, still allowing future authentication methods to use existing SASL
mechanisms if necessary.
We recall that Figure 1-1 illustrates the architecture of SASL incorporating EAP
including where the EAP interface is located in the SASL library directory and how the
EAP interface connects SASL with legacy and future EAP authentication methods. This
project proposes to incorporate EAP into SASL to enhance security of SASL and to
provide a pathway for easy incorporation of future EAP enhancements into SASL.
In next chapter we propose an updated EAP-TLS-PSK which is called EAP -
Advanced Encryption Standard - Pre-Shared-Key (EAP-AES-PSK).
14
CHAPTER 3
EXTENSIBLE AUTHENTICATION
PROTOCOL – ADVANCED ENCRYPTION
STANDARD – PRE-SHARED KEY
(EAP-AES-PSK)
We propose a new EAP method: EAP - Advanced Encryption Standard - Pre-
Shared Key (EAP-AES-PSK) that is modified from EAP - Transport Layer Security -
PSK (EAP-TLS-PSK) for two primary reasons: to reduce the number of message
exchanges between the authenticator and the peer, and to ease the implementation and
management of Simple Authentication and Security Layer (SASL) while maintaining the
same security level that EAP-TLS-PSK provides.
TLS is a cryptographic protocol that provides many security algorithms. A peer
negotiates for an algorithm that TLS supports. However, TLS specifies that no data must
be sent when TLS initiates. Therefore, if we want to continue to use TLS, we must
modify the TLS implementation to be able to carry data in the initialization. We decided
not to use TLS in order to ease the implementation and management, and the AES used
in EAP-AES-PSK is one of the symmetric ciphers that TLS provides. As a benefit, there
is no notoriously known attack in AES.
15
At first glance, it may appear that EAP-AES-PSK is the same as EAP-PSK. EAP-
AES-PSK is similar to EAP-PSK, but is not the same. EAP-AES-PSK intends to
authenticate twice (in Phase 1 and Phase 2) to allow the use of password-based legacy
EAP methods in Phase 2 of EAP-AES-PSK, as well as to provide more security. At the
end of each phase, the end points generate an outer Master Session Key (MSK) and an
inner MSK. From the outer and inner MSKs, EAP-AES-PSK derives a MSK to protect
subsequent data. EAP-AES-PSK supports fragmentation and reassembly.
This chapter explains the details of EAP-AES-PSK and discusses the possible
attacks and insecure data exchanges in the currently available Simple Authentication and
Security Layer (SASL) mechanisms, which lead to the motivation for the study of this
area.
3.1 Approach
EAP-AES-PSK, similar to other current EAP outer methods, consists of two
primary phases. Phase 1 is similar to the EAP-PSK method. Rather than using the EAP
server to generate a required certificate, the process uses the EAP-PSK scheme to
authenticate mutually, generating a Transient EAP Key (TEK), to establish the secure
protected channel necessary for further connectivity. At the beginning of Phase 1, a
server and a client derive the Authentication Key (AK) and the Key Derivation Key
(KDK) from PSK [5] such as following pseudo code in Figure 3-1. Note that actual
implementation should be more efficient since this pseudo code is to provide
straightforward explanation.
16
key_setup(psk, …){
coutner = 0
set ak[16] with 0s
set kdk[16] with 0s
aes_128(psk, ak, …)
aes_128(psk, kdk, …)
ak ^= counter++
kdk ^= counter
aes_128(psk, ak, …)
aes_128(psk, kdk, …)
}
Figure 3-1: Key Setup Algorithm in EAP-AES-PSK [5]
Both AK and KDK are 16 bytes. AK is used to mutually authenticate the EAP
peer and the EAP server and KDK is used to derive other necessary keys. At the end of
Phase 1, the outer master session key (MSK) derived from the KDK, peer nonce, and
more such as outerMSK = key_derive (KDK, RAND_P, …) in Figure 3-2. The
outer MSK will be used as one of these inputs for deriving MSK after a successful
authentication is made.
All MSKs of EAP-AES-PSK must be derived in the algorithm in Figure 3-2.
key_derive (kdk, rand_p, …){
hash[16]
counter = 1
aes_128(kdk, rand_p, hash, …)
hash ^= counter
aes_128(kdk, hash, …)
hash ^= counter++
for i = 0 to 3
hash ^= counter
aes_128(kdk, hash, msk[i * 16], …)
hash ^= counter++
}
Figure 3-2: Key Derive Algorithm in EAP-AES-PSK [5]
17
Phase 2 performs further authentication in the initially-established AES secure
tunnel from Phase 1. Unlike EAP-TLS-PSK, EAP-AES-PSK does not employ the EAP-
TLV method to further authenticate EAP identity. At the conclusion of Phase 2, inner
MSK is derived from KDK, peer secret (i.e., password), and more such innerMSK =
key_derive (KDK, password, ). After successful authentication is made,
MSK is derived from KDK, the concatenation of the first 8 bytes of outer and inner
MSKs, and more such as MSK = key_derive (KDK, outerMSK[0..7] ||
innerMSK[0..7], ). MSK is to protect subsequent data. For more secure
communication, MSK is needed to update in timely manner. For instance, every round
trip both the server and the client renew the MSK to protect subsequent data.
3.2 EAP-AES-PSK Message Flows and Packet Format
The typical packet format of the EAP-AES-PSK messages would have the
appearance as is described in Figure 3-3. The first byte of the EAP-AES-PSK packet
indicates Request, Response, Success, or Failure. The second byte indicates message
identifier for each round trip between a server and a peer. After each round trip, the
identifier should be updated to the next available identifier from 0 to 255. The next two
bytes contain the total length of the EAP-AES-PSK packet. The next byte is for the EAP
type field. EAP-AES-PSK should set this value to 255 as this is an experimental EAP
method. The next byte is for flags. The subsequent bytes are for data. Thus, EAP-AES-
PSK needs at least 6 bytes for the header.
18
0 1 2 3
5
6
Code / 1 byte
1 = Request
2 = Response
3 = Success
4 = Failure
Identifier / 1 byte
Total Length of Packet /
2 bytes
Type / 1 byte
EAP-AES-PSK
Data / 1014 bytes
4
Flags / 1 byte
M = More fragment
R = Reserved
R = Reserved
R = Reserved
R = Reserved
R = Reserved
V = Major Version = 1
V = Minor Version = 0
Figure 3-3: EAP-AES-PSK Packet Format
EAP-AES-PSK, as described in Section 3.1, may consist of two primary phases of
message flows. EAP-AES-PSK standard authentication is comprised of four messages,
i.e., two round trips; see Figure 3-4. EAP-AES-PSK assumes that the pre-shared key
(PSK) is already known only to the EAP peer and EAP sever and that the distribution of
the PSK is outside of the scope of the EAP-AES-PSK mechanism. Note that ‘||’ within
Figure 3-4 means concatenation.
19
Figure 3-4: EAP-AES-PSK Authentication Message Exchanges
In the EAP-AES-PSK method, the first message sent by the server to the peer
contains:
An EAP-Request with EAP-Type=EAP-AES-PSK;
Flags : MRRRRRVV;
20
- M = More fragments
- R = Reserved (must be zero)
- R = Reserved (must be zero)
- R = Reserved (must be zero)
- R = Reserved (must be zero)
- R = Reserved (must be zero)
- V = 1 (major version)
- V = 0 (minor version)
The stated server identity (ID_S); and
A server 16-byte random challenge (RAND_S).
The second message is sent by the peer to the server containing:
An EAP-Response with EAP-Type=EAP-AES-PSK;
Flags: MRRRRRVV (major version = 1);
A notice that it will authenticate to the server by proving that it is able
to compute a particular Message Authentication Code (MAC_P),
which is a function of the two challenges and AK:
MAC_P = CMAC-AES-128(AK, ID_P||ID_S||RAND_S||
RAND_P);
A peer 16-byte random challenge (RAND_P); and
The stated peer identity (ID_P).
Like EAP-PSK [5], Authentication Key (AK) is used to mutually authenticate the
EAP peer and the EAP server. AK is a static long-lived key derived from the PSK.
However, AK is not a session key.
The third message is sent by the server to the peer containing:
An EAP-Request packet with EAP-Type=EAP-AES-PSK;
Flags: MRRRRRVV (major version = 1);
21
A notice that it will authenticate to the peer by proving that it is able to
compute another MAC (MAC_S), which is a function of the peer’s
challenge and AK: MAC_S = CMAC-AES-128(AK, ID_S||
RAND_P); and
An established protected channel (PCHANNEL_S) to:
- Confirm that it has derived session keys (at least the TEK); and
- Give a protected result indication of the authentication.
PCHANNEL_S is an encrypted message by AES encryption with TEK that
contains information about Phase 1 authentication result. If the client is able to decrypt
PCHANNEL_S, the server verifies the client’s identity since TEK is derived directly
from PSK and never transported over the Internet.
The fourth message is sent by the peer to the server containing:
An EAP-Response packet with EAP-Type=EAP-AES-PSK;
Flags: MRRRRRVV (major version = 1); and
A notice that the establishment of the protected channel
(PCHANNEL_P) is complete to:
- Confirm that it has derived session keys (at least the TEK); and
- Give a protected result indication of the authentication.
PCHANNEL_P is an encrypted message by AES encryption with TEK that
contains information about Phase1 authentication result. If the server is able to decrypt
PCHANNEL_P, the client verifies the server’s identity since TEK is derived directly
from PSK and never transported over the Internet.
22
The internal method (in Phase 2) can be any other EAP method, such as EAP-
GTC, and will allow for devices to establish safe authentication using the EAP-AES-PSK
method. For instance, the internal method is encrypted by AES 128 encryption.
Figure 3-4 shows messages 5 through 8 are engaged in the exchange of user
credentials using EAP-Generic Token Card (EAP-GTC) [2] exchanges. EAP-GTC has a
data field in the Request includes a displayable message and a length of the packet of
EAP-GTC is determined by adding message length to EAP-GTC header length. A
Response must reply to the Request. We assume message 5 through 6 contain typical
EAP header in Figure 3-3 with an EAP-Response packet with EAP-Type=EAP-AES-
PSK.
The fifth message is sent by the server to the peer containing:
An EAP-Request packet with EAP-Type=EAP-GTC; and
A displayable message that prompts user id and password.
The sixth message is sent by the peer to the server containing:
An EAP-Response packet with EAP-Type=EAP-GTC; and
A response to the Request.
Both the seventh and eighth messages are sent by the server to the peer
containing:
An EAP-Success or Failure with no data.
Even though the seventh and eighth messages are exactly the same packets, we
still need to send the eighth message to satisfy the definition of successful authentication.
Successful authentication is defined in this document as involving both authentication
23
and authorization; even though the peer may pass authentication to the server, the peer
may not access the server due to policy reasons. Thus, we need to send the eighth
message although the message is a repeat of the previous seventh message. For instance,
a peer has a basic service right on a server and the peer tries to access a premium service
on the server. The peer probably passes the authentication, but not the authorization. In
the case, the server sends EAP-Success within seventh message and EAP-Failure within
eighth message.
While the EAP-AES-PSK method appears to offer 8 message exchanges at the
minimum, both the outer and inner EAP methods are established using PSK and AES.
This speedier method is expected to minimize message exchange latency that is found in
other methods, while maximizing the feature set of this method.
3.3 Features of EAP-AES-PSK
Table 3-1 summarizes the features that EAP-TLS-PSK and EAP-AES-PSK
provides. Both EAP methods propose tunneling support within EAP-PSK. The last
column shows that EAP-AES-PSK brings fewer message exchanges between the client
and server as compared to the EAP-TLS-PSK method. Details of the features are shown
in Section 3.4.
Table 3-1: Features of Pre-Shared Key Methods
EAP-TLS-PSK [14] EAP-AES-PSK (proposed)
Fragmentation/
Reassembly
Yes
By use of TLV Flags ‘More
Fragment’ bit
Yes
EAP-AES-PSK flags contain
‘More Fragment’ bit
Channel Binding Yes
Inherited from EAP-PSK
Yes
Inherited from EAP-PSK
24
Table 3-1 Continued
Fast Reconnection Yes Yes
Key Strength 128 bit
Inherited from EAP-PSK
128 bit
Inherited from EAP-PSK
Minimum # of
Messages Exchanges
11
Phase 1 (4) + Phase 2 (7)
8
Phase 1 (4) + Phase 2 (4)
Tunnel Support Yes
TLS tunnel
Yes
AES tunnel
Difficulty of
Implementation
Harder than EAP-AES-PSK Easier than EAP-TLS-PSK
3.4 EAP-AES-PSK Supporting Aspects
This section explains details of EAP-AES-PSK supporting aspects such as
fragmentation, channel binding, fast reconnection, key strength, number of message
exchanges, and tunnel support.
3.4.1 Fragmentation
The ideal EAP method supports fragmentation and reassembly. As RFC3748
states, EAP methods should support fragmentation and reassembly if EAP packets can
exceed the minimum Maximum Transmission Unit (MTU) of 1020 bytes [2].
Fragmentation in EAP-TLS-PSK can be done through the use of flags within the TLV in
Phase 2 only.
EAP-AES-PSK has its own 1 byte flags field such as MRRRRRVV in Figure 3-3.
If the M bit is 1 in the received EAP packet, there will be more data. If following the size
of the data is larger than the minimum MTU, M in the flags is set to 1. However
25
fragmentation and reassembly may be needed only in Phase 2 of EAP-AES-PSK. Since
Phase 1 of EAP-AES-PSK is defined to support fragmentation and reassembly in its
definition, MTU sizes of EAP-AES-PSK packets will not exceed 1020 bytes when
normally transmitted in a network.
3.4.2 Channel Binding
The verification within an EAP method of integrity-protected channel properties
is the process of channel binding. For instance, endpoint identifiers within an EAP
method can be compared to stored values (in AAA service systems).
EAP-AES-PSK uses an EAX mode of operation, an authenticated-encryption with
associated data mode of operation for block ciphers, to provide channel binding as stated
in Section 2.2.3 of EAP-PSK [5]. We explained earlier how EAP-AES-PSK achieves
channel binding in Section 3.2.
3.4.3 Fast Reconnection
The ability to create a new or refreshed security association, in the case where a
security association has been previously established, in a more efficient manner or in a
smaller number of round-trips is the goal of fast reconnection. Fast reconnection is
optional in EAP-AES-PSK since, by having fast reconnection, EAP-AES-PSK saves one
message round trip.
The server and peer must minimally cache the server and peer nonces, but not
master secret, in order to have fast reconnection within EAP-AES-PSK. The master
secret will be regenerated from the pre-shared key, server and peer nonce, and AES
ciphersuite. The peer attempts to resume a session by sending an encrypted message
26
along with peer nonce from a previous session. The message should be encrypted using
Transient EAP Key (TEK) derived from the pre-shared key and the AES ciphersuite. If
the server has a matched peer nonce and is able to decrypt the message, the server will
respond by sending an encrypted message to inform the peer of the server’s successful
verification of the peer. Then, EAP-AES-PSK Authentication Phase 1 establishes a
secure tunnel and the conversation continues on to Phase 2. An example of fast
reconnection message exchanges is shown in Section 4.2 that presents verification of
EAP-AES-PSK functionality.
3.4.4 Key Strength
Following RFC3748 directives, if the method derives keys, then the effective key
strength must be estimated. This estimate is meant for potential users of the method to
determine if the keys produced are strong enough for the intended application. Since the
keys within EAP-AES-PSK are derived by AES 128 ciphersuite like the EAP-PSK
method, EAP-AES-PSK has the same key strength as EAP-PSK, which is 128 bit.
However, the key strength of EAP-AES-PSK can be upgraded to 196 or 256 bit by
replacing AES algorithm function. No one can be able to tell how long any cryptographic
algorithm including the AES algorithm will last secure regardless key strength. As
following National Institute of Standards and Technology (NIST) [1], AES algorithm
approximately has 3.4 x 10
38
possible 128-bit keys, 6.2 x 10
57
possible 192-bit keys, and
1.1 x 10
77
possible 256-bit keys.
27
3.4.5 Number of Message Exchanges
This indicates the number of message exchanges between a client and a server.
EAP-AES-PSK has 8 message exchanges required in a normal configuration, while EAP-
TLS-PSK needs 11 message exchanges to establish a proper secure connection. Both
EAP-AES-PSK and EAP-TLS-PSK need 4 message exchanges in Phase 1, but EAP-
AES-PSK requires only 4 message exchanges in Phase 2 while EAP-TLS-PSK requires 7
message exchanges. Since EAP-AES-PSK does not require using Type Length Value
(TLV) for crypto-binding in Phase 2, EAP-AES-PSK has 3 less message exchanges than
EAP-TLS-PSK has.
3.4.6 Tunnel Support
Unlike EAP-TLS-PSK, EAP-AES-PSK uses Advanced Encryption Standard
(AES) [1] instead of Transport Layer Security (TLS). AES published by the NIST, is
known to provide strong encryption and authentication. EAP-AES-PSK supports strong
encryption to prevent eavesdropping and mutual authentication and to guarantee that user
credentials are transmitted over legitimate networks. In the EAP-AES-PSK method, the
fifth to the seventh exchanged messages are protected by AES encryption tunnel support.
Section 3.2 explains how this works and Section 4.2 illustrates an example of actual
messages in communication.
3.5 Protections Against Security Risks
Typical attacks on Simple Authentication and Security Layer (SASL)
mechanisms include the dictionary attack, replay attack, and Man-In-The-Middle
(MITM) attack as well as re-keying issues. Extensible Authentication Protocols (EAP)
28
such as EAP-AES-PSK in SASL provides greater protection against the protections
against those previously listed attacks based on the designs of both SASL and EAP and
their combined usage.
3.5.1 Dictionary Attack
A dictionary attack is a technique used to get around an authentication mechanism
for accessing a computer system by guessing typical passwords. In many cases, the
credential exchanges are open to attacks, such as dictionary attacks, on a password. This
attack could occur in SASL mechanisms that authenticate users by user ID and password.
For instance, in Figure 3-5, the intruder guesses on Bob’s password that matches with
Bob’s ID to gain access to Alice’s system.
BobAlice
Intruder
Network
Guessing passwords
Figure 3-5: Dictionary Attack
EAP methods in SASL create a secured Advanced Encryption Standard (AES)
tunnel between the client and the authentication server first. Some legacy SASL
mechanisms, such as password based-authentication methods, could be used to
29
authenticate a client. Since user credential data transmission is performed only within a
protected tunnel, SASL incorporating EAP methods is safe from the dictionary attack.
3.5.2 Replay Attack
Attackers could obtain a message from a legitimate user with accesses into a
network and replay that message later. This attack is called the replay attack. Replay
attack causes unauthorized authentication or denial of service (DoS) [19].
The authentication process in EAP-AES-PSK is based not only on Pre-Shared key
(PSK), but also on nonces such as server and client random numbers. EAP-AES-PSK
server and clients exchange their nonces by including within the first and second
messages of EAP-AES-PSK. Thus, the intruder will not gain successful authentication
even if the intruder captures a message and resends to the server during the authentication
process. The current server nonce will be not same as the server nonce from the last
authentication process. Therefore, SASL incorporating EAP methods are safe from the
replay attack.
3.5.3Man-In-The-Middle (MITM) Attack
Some mechanisms in SASL define authentication as a one-way action, such as a
simple clear text password mechanism, PLAIN, although Generic Security Services
Application Program Interface (GSSAPI [16]) [18], an application programming interface
for programs to obtain security services [10], provide mutual authentication that uses
Kerberos V. For example, when a client logs onto a network, only the server requires the
client authentication. Because of one-way authentication, an attacker who resides
between a client and a server can participate in the login exchange without the knowledge
30
of the client or the server (see Figure 3-6). This attack is known as the Man-In-The-
Middle [3] attack.
Client Server
MITM
Network
Figure 3-6: Man-In-The-Middle (MITM) Attack
Typically MITM attack happens when mutual authentication is not performed.
However, SASL incorporating EAP methods do mutual authentication between a client
and a server. For instance, EAP-AES-PSK authenticates mutually via sending and
receiving message 3 and 4 that contain PCHANNEL_S and PCHANNEL_P, encrypted
messages by Advance Encryption Standard (AES) encryption. If the client is able to
decrypt PCHANNEL_S message from the server, the server achieves verifying the
client’s identity because TEK, a key to encrypt or decrypt a message, is derived directly
from PSK and never transported over the Internet. If the server is able to decrypt
PCHANNEL_P, the client achieves verifying the client’s identity. Thus, SASL
incorporating EAP methods could protect against MITM attacks.
31
3.5.4 Re-keying
The SASL framework does not provide re-keying services. Thus, cryptographic
keys age and become insecure as they are used and as time goes by [9]. EAP generates
keying materials, such as Master Session Key (MSK) and Extended Master Session Key
(EMSK), during the authentication process. MSK, which is at least 64 octets in length, is
a keying material that is derived between the client and the server and carried by the EAP
method. The EMSK is extended from MSK and is reserved for future uses that are not yet
defined [2]. Secure EAP methods such as EAP-AES-PSK renew MSK in time manner.
For instance, EAP-AES-PSK updates keys every round trip between a server and a peer.
If SASL uses EAP keying services, future re-keying services of EAP will be
automatically extended into the SASL mechanism and allow SASL incorporating EAP
methods to support stronger cryptographic keys.
3.5.5 Data Encryption
Existing SASL, as defined, does not strongly encrypt messages in a
communication between a client and a server. Standalone SASL only provides a 64 bit
encryption scheme. Thus, attackers could easily sniff messages in the communication by
using network protocol analyzers.
EAP in SASL solves the data encryption issue. Data in EAP-AES-PSK is
encrypted by AES 128 ciphersuite or higher. EAP generates MSK after a successful
authentication thus the MSK is used in AES 128 ciphersuite to encrypt data. Therefore,
SASL incorporating EAP provides secure data transfer.
32
CHAPTER 4
VERIFICATIONS
Currently, there are two publicly available Simple Authentication and Secure
Layer (SASL) libraries available: Cyrus SASL library from Carnegie Mellon University
and the GNU SASL library. In this project, Cyrus SASL library was selected randomly
and used as part of the implementation as well as Hostapd and Wi-Fi Protected Access
(WPA) supplicant [15] for SASL and EAP frames respectively. In Chapter 3 we proposed
a new Extensible Authentication Protocol (EAP) method, EAP - Advanced Encryption
Standard - Pre-Shared Key (EAP-AES-PSK). EAP-AES-PSK is successfully built on the
SASL library and used for simple file transfer. This chapter details the project outcomes
and evaluates the result.
4.1 Outcomes
This project proposes to incorporate EAP into SASL to enhance the security of
SASL and to provide a pathway for the easy incorporation of future EAP enhancements
into SASL. The practical details on how to merge EAP into a SASL application source
code library is stated in Appendix B, including documentation about SASL incorporating
EAP such as implementation of SASL incorporating EAP: EAP interface,
implementation of SASL incorporating EAP-PSK, implementation of SASL
33
incorporating EAP-AES-PSK, SASL Application: basic file transfer application requiring
authentication, and a general SASL installation user guide, and a basic file transfer SASL
application user guide.
4.2 Evaluation
Evaluation of this project contains three parts: verification of functionality of a
SASL application incorporating EAP, arguments to show how common security risks are
addressed, and a performance evaluation. In Section 3.5, we already argue that SASL
incorporating EAP will reduce or prevent the considerable security risks such as the
dictionary attack, replay attack, and Man-In-The-Middle (MITM) attack as well as re-
keying issues.
4.2.1 Verification of Functionality of a SASL Application incorporating EAP
The outcomes specified in Section 4.1 above are performed for functionalities and
secure data encryption by using network protocol analyzers. The network protocol
analyzer examined transmissions to verify that the messages in the communication are
secure. For instance, captured messages between a client and a server in a SASL
application was compared with a result that we expect what the captured messages should
be.
The configuration of EAP-AES-PSK must be preplanned before we use EAP-
AES-PSK. Table 4-1 is a configuration example of EAP-AES-PSK. Both a server and a
client must set the Pre-Shared Key and ID respectively to be “thisistemporarykey and
“EAP-AES-PSK_server/ EAP-AES-PSK_client.” The client needs to provide a user ID
34
and a user password for Phase 2 that will be used in the inner method, i.e., “user1” and
“pass1.”
Table 4-1: Configuration of EAP-AES-PSK
Server Client
Pre-Shared Key Thisistemporarykey
ID EAP-AES-PSK_server EAP-AES-PSK_client
User ID for Phase2 N/A user1
User Password for Phase2 N/A pass1
The following boxed messages in octet form were captured during a SASL
incorporating EAP-AES-PSK communicated. Each line starts with a 7 digit line number
in octet form followed by 16 bytes, such as od -x format, in UNIX-like machine
format. Note that ‘||’ means concatenation and ‘n’ (in ‘[n]’) represents a number of
byte(s), i.e., [3] means 3 bytes.
When EAP-AES-PSK is initialized, both the server and the client derive
Authentication Key (AK) and Key Derivation Key (KDK) from the MSK above.
AK [16]:
0000000 eb69 f5eC 59dc 1cd8 2f11 cd36 6f29 3fd3
KDK [16]:
00000000 3c4b 340c e8e1 3780 9f58 f8be bbac 8d04
35
First message (server client):
(EAP-Request [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
RAND_S [16] || ID_S [18]):
0000000 0101 0028 ff02 2da5 f99e fc18 162b 2add
0000020 5534 7ba5 f88d 4541 502d 4145 532d 5053
0000040 4b5f 7365 7276 6572
EAP-Request, EAP-Response, EAP-Success, and EAP-Failure are defined to
values 1, 2, 3, and 4, respectively.
Second message (client server):
(EAP-Response [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
RAND_S [16] || RAND_P [16] || MAC_P [16] || ID_P [18]):
0000000 0201 0048 ff02 2da5 f99e fc18 162b 2add
0000020 5534 7ba5 f88d 1a4c b33d 8f83 540d 1e96
0000040 077b ee3a 2dfa a0be dffe e543 821a cddd
0000060 ca9c 0c52 5a34 4541 502d 4145 532d 5053
0000080 4b5f 636c 6965 6e74
Third message (server client):
(EAP-Request [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
RAND_S [16] || MAC_S [16] || PCHANNEL_S):
36
0000000 0102 003b ff02 2da5 f99e fc18 162b 2add
0000020 5534 7ba5 f88d 3306 7a2c 52fe 72df 33d0
0000040 e809 d83d e8da 0000 0000 c73d 04dc c807
0000060 1f9c 6e59 0e60 9cdc 13ae ed
Fourth message (client server):
(EAP-Request [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
RAND_S [16] || PCHANNEL_P):
0000000 0202 002b ff02 2da5 f99e fc18 162b 2add
0000020 5534 7ba5 f88d 0000 0001 4d59 d5c1 0362
0000040 0817 7c68 c053 4a2b e472 bb
Fifth message (server client):
(EAP-Request [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
nonce [4] || tag [16] || EAP-Request [1] || identifier [1] || Length [2] || EAP-GTC [1] ||
“UserID? Password?”):
0000000 0103 0032 ff02 0000 0000 2a4f ec4a eb73
0000020 7123 eaf3 9073 701e 04ae 6cbe c0a4 48fe
0000040 c8a3 8a2c 64d2 bb40 9cba dcb8 a680 7583
0000060 c86b
Nonce and tag are needed to establish the AES tunnel. Nonce should be 16 bytes.
The first 12 bytes are set to be zeros and only the last 4 bytes are to be defined. Thus,
37
from the second EAP-Request of the fifth message is where the inner EAP method starts
encryption.
Sixth message (client server):
(EAP-Response [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
nonce [4] || tag [16] || EAP-Response [1] || identifier [1] || Length [2] || EAP-GTC [1] ||
“user1/pass1”):
0000000 0203 002b ff02 0000 0001 0a07 c1cc 67fb
0000020 b47c 000a 3c45 e500 b200 393e 82cd 2cd7
0000040 2dba 41d7 cd10 7327 b826 75
Seventh message (server client):
(EAP-Response [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1]):
0000000 0304 0006 ff02
EAP-AES-PSK needs 8 message exchanges. However EAP-AES-PSK within the
SASL framework does not require the eighth message, which is exactly the same as the
seventh message. We may send the seventh message again for the last message, but it
wastes time and is unnecessary because the SASL framework is required to send
“SASL_OK”, indicating successful authentication is made, and that can replace the
eighth message of EAP-AES-PSK in the EAP framework.
After successful authentication in SASL incorporating EAP (using EAP-AES-
PSK), the Master Session Key (MSK) is derived to protect subsequent data from
manipulating the outer and inner MSKs using KDK.
38
Outer MSK [64]:
0000000 33d8 4480 e8da 644f e090 78c6 0a5d 97c6
0000020 534f b7a7 d899 6afd 62c8 593d 76e0 3635
0000040 8896 8f1f 9daa b463 6dbc 7ff0 f368 2d52
0000060 cddb e146 59fe e84d fedd 3fed 15e4 6d4d
Inner MSK [64]:
0000000 0440 ef76 6652 9b29 42a8 cbd0 4946 5891
0000020 8722 f109 02ef 5062 0b60 8859 4ade 46c5
0000040 2bdb 02a0 a87a d242 e6d8 3421 0c82 b43a
0000060 4def 7612 a6bd 0850 dee2 24ad b27D fb32
MSK [64]:
0000000 ca99 f0ec 8a13 c908 aff9 68f5 24cb 9eb1
0000020 440c d40a 77b0 3373 cf0e 22dd 8353 530c
0000040 7e92 9611 3543 88f8 f90b 2077 9193 0e77
0000060 5f87 6561 ccd1 481b ed58 cae5 e9a1 d31c
The following two extra messages are from fast reconnection, described in
Section 3.4, after the successful authentication above. Both the server and the client saved
their nonces.
First message in fast reconnection (client server):
(EAP-Request [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
RAND_P [16] || PCHANNEL_P):
39
0000000 0107 002b ff02 1a4c b33d 8f83 540d 1e96
0000020 077b ee3a 2dfa 0000 0000 c73d 04dc c807
0000040 1f9c 6e59 0e60 9cdc 13ae ed
Second message in fast reconnection (server client):
(EAP-Request [1] || identifier [1] || Total Length [2] || EAP-AES-PSK [1] || flags [1] ||
RAND_S [16] || PCHANNEL_S):
0000000 0207 002b ff02 2da5 f99e fc18 162b 2add
0000020 5534 7ba5 f88d 0000 0001 4d59 d5c1 0362
0000040 0817 7c68 c053 4a2b e472 bb
If the server and the client are able to decrypt the message that is encrypted by
each other, then EAP-AES-PSK Authentication Phase 1 establishes a secure tunnel and
the conversation continues on to Phase 2. Otherwise, both the server and the client start
normal authentication.
4.2.2 Performance Evaluation
Authentication Time Test (Access Time Test):
The authentication time test was executed on the SASL only-application (i.e.,
ANONYMOUS), SASL using EAP-PSK method, and SASL EAP-AES-PSK. Figure 4-1
and Table 4-2 show the amount of time needed to perform authentication in
ANONYMOUS, EAP-PSK, and EAP-AES-PSK. Note that all performance tests were
executed on machines with 500 MHz CPU/256 MB memory and 700 MHz CPU/256 MB
memory for the server side and the client side respectively.
40
The server is always running and waiting for a client connection. Thus, server
authentication time is measured from the time a new client connects to the time the client
disconnects. Client authentication time is measured from the time the client initializes to
the time the client ends.
The authentication time for the each method are measured in both the controlled
environment and the un-controlled environment. Figure 4-1 and Table 4-2 shows both the
results from both the controlled experiment and the uncontrolled experiment. The
controlled environment is a test setup such as using two machines and a router in home
network (or private network). In the controlled environment, the messages are never
transported over Internet or public network. Thus, we can minimize the chance of un-
wanted variants affect on the authentication time. Internet is one of the un-controlled
environments where we cannot have all controls to maximize and to accurate test results.
The test in the un-controlled environment was executed on one machine (a server), is at
University of New Hampshire (UNH) and another machine (a client), is in Epsom, NH
where is about 27 miles away from UNH over Internet.
41
0
100
200
300
400
500
ANONYMOUS EAP-PSK EAP-AES-PSK
Authentication Method
Authentication Time [ms]
Server in the Controlled Experiment Client in the Controlled Experiment
Server in the Un-Controlled Experiment Client in the Un-Controlled Experiment
Figure 4-1: Authentication Time for Each Method
Table 4-2: 95% Confidence Level Authentication Time for each Method
Authentication Time [ms]
\Method
ANONYMOUS EAP-PSK EAP-AES-PSK
Controlled
Experiments
Server 88.5±0.5 101±0.5 113±0.7
Client 27.7±0.4 38.1±0.4 40.4±0.4
Un-Controlled
Experiments
Server 290±6 450±27 467±16
Client 227±3 386±26 395±8
The authentication time in EAP-PSK and EAP-AES-PSK took longer compared
to the time in ANONYMOUS because ANONYMOUS only needs 2 message exchanges
while EAP-PSK and EAP-AES-PSK requires 4 and 7 message exchanges along with
AES encryption.
AES Encryption Time Test:
We need to know how much AES encryption time affects on the performance of
SASL incorporating EAP-AES-PSK. EAP-AES-PSK, the new proposed EAP method,
uses AES encryption to protect data communications after successful authentication.
42
Figure 4-2 & Table 4-3 and Figure 4-3 & Table 4-4 show the completion time
examined on SASL application incorporating EAP-AES-PSK in the controlled
environment and the un-controlled environment respectively. The SASL application
transfers different sizes of plain text and AES encrypted text files, such as 1 KB, 10 KB,
100 KB and 1000 KB. The text of RFC2800, the one of IETF standards, was randomly
selected as a data file for the test and the file was truncated to satisfy the required file
sizes; 1 KB, 10 KB, 100 KB and 1000 KB. This completion time tests measured the time
from the authentication to the file transfer, which is the sum of the access time and the
transfer time.
Both (a) and (b) in Figure 4-2 and 4-3 have 800 elements, such as 2
(encrypted/plain text) x 4 (1, 10, 100, and 1000 KB) x 100 (trials). Since the completion
time is similar, whether the file is encrypted or not in each different size, we see 4~5
major horizontal lines. As file size increases, Both Figure 4-2 & Table 4-3 (from the
controlled experiments) and Figure 4-3 & Table 4-4 (from the un-controlled experiments)
show that AES encryption time does not increase much. As following Schneier’s AES
performance test [21], the test exposes that AES algorithm performs efficiently even in
large data, i.e., larger than 1 MB. AES algorithm can be coded in assembly for better
performance in where needs to run fast [21]. Thus, SASL file transferring application
incorporating EAP-AES-PSK takes an almost comparable amount of time to transfer files
from one system to the other as compared to the time to transfer plain text files.
43
(a)
(b)
Figure 4-2: (a) Server Completion Time in the Controlled Environment,
(b) Client Completion Time in the Controlled Environment
44
(a)
(b)
Figure 4-3: (a) Server Completion Time in the Un-Controlled Environment,
(b) Client Completion Time in the Un-Controlled Environment
45
Table 4-3: 95% Confidence Level Completion Time in the Controlled Environment
Completion Time [ms]
\File size [KB]
1 10 100 1000
Server Plain Text 119±0.8 121±0.7 138±0.8 301±1.3
AES Encrypted Text 119±0.7 122±0.8 160±0.9 576±0.9
Client Plain Text 45.9±0.5 47.9±0.4 63.7±0.5 227±0.8
AES Encrypted Text 46.2±0.5 49.2±0.5 86.5±0.6 501±1.0
Table 4-4: 95% Confidence Level Completion Time in the Un-Controlled Environment
Completion Time [ms]
\File size [KB]
1 10 100 1000
Server Plain Text 456±5 540±5 2586±62 22692±17
2
AES Encrypted Text 456±9 577±15 2835±74 23363±24
0
Client Plain Text 402±5 484±5 2560±72 22556±16
5
AES Encrypted Text 402±7 521±15 2646±64 22806±16
1
46
CHAPTER 5
CONCLUSION
Authentication and access control of users are key functions to establish secure
communication. However, successful authentication does not always occur over insecure
network connections. Weak authentication methods are subject to the risks of insecure
communication such as dictionary attack, replay attack, and Man-In-The-Middle (MITM)
attack.
In this thesis, we demonstrated the incorporation of Extensible Authentication
Protocol (EAP) into Simple Authentication and Security Layer (SASL) to enhance the
security of SASL and to provide a pathway for easy incorporation of future EAP
enhancements into SASL in addition to the establishment of secure communication.
Moreover, we proposed a new EAP method, EAP-Advanced Encryption Standard-Pre-
Shared Key (EAP-AES-PSK) to provide strong authentication and implemented it on the
Cyrus SASL library that is one of the publicly available SASL implementations.
The evaluation of this thesis on the functionality of a SASL application
incorporating EAP, the arguments to show how common security risks are addressed, and
the performance evaluation shows that SASL incorporating EAP provides stronger
security services. The performance test results demonstrated that AES encryption does
47
not require much more time, and as a result it, this new EAP method, EAP-AES-PSK,
can be used in transferring a large sized file.
For the future, EAP-AES-PSK needs a more efficient way to re-authenticate since
current re-authentication schemes reduce only 1 round trip. And interoperability with
other EAP methods that use other encryptions is an additional concern that warrants
further study.
48
BIBLIOGRAPHY
[1] “ADVANCED ENCRYPTION STANDARD (AES)”, Federal Information
Processing Standards (FIPS) Publication 197, November 26, 2001,
http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
[2] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and Levkowetz, H., "Extensible
Authentication Protocol (EAP),” RFC 3748, June 2004.
[3] Asokan, N., Niemi, V., and K. Nyberg, "Man-in-the-Middle in Tunneled
Authentication,” http://www.saunalahti.fi/~asokan/research/mitm.html, Nokia
Research Center, Finland, October 24, 2002.
[4] Authentication Protocols. Retrieved November 23, 2006,
http://www.comptechdoc.org/independent/networking/protocol
/protauthen.html
[5] Bersani F., Tschofenig H., “The EAP-PSK Protocol: A Pre-Shared Key Extensible
Authentication Protocol (EAP) method,” RFC 4764, January 2006.
[6] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and T. Wright,
"Transport Layer Security (TLS) Extensions,” RFC 3546, June 2003.
[7] Cheng, P., and Glenn, R., “Test Cases for HMAC-MD5 and HMAC-SHA-1,” RFC
2202, Retrieved November 15, 2006, http://tools.ietf.org/html/rfc2202
[8] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0,” RFC 2246, November
1998.
[9] Extensible Authentication Protocol. (2006, November 14). In Wikipedia, The Free
Encyclopedia. Retrieved November 15, 2006, http://en.wikipedia.org/w/
index.php?title=Extensible_Authentication_Protocol&oldid=87776933
[10] Generic Security Services Application Program Interface. (2006, October 31). In
Wikipedia, The Free Encyclopedia. Retrieved November 21, 2006,
http://en.wikipedia.org/w/index.php?title=Generic_Security_Services_Applicatio
n_Program_Interface&oldid=84773404
[11] Hiller, T., Palekar, A., and Zorn, G., “A Container Type for the Extensible
Authentication Protocol (EAP),” Retrieved November 06, 2006,
http://bgp.potaroo.net/ietf/all-ids/draft-hiller-eap-tlv-00.txt
49
[12] IEEE Standards for Local and Metropolitan Area Networks: Port-Based Network
Access Control, IEEE Std 802.1X-2004, 13 December 2004.
[13] Kerberos: The Network Authentication Protocol (2006, November 18). Retrieved
November 23, 2006, http://web.mit.edu/kerberos/#what_is
[14] Kim, M., Valcourt, S., and Bartoš, R., “Selecting a Standard Outer Method for
EAP,” Technical Report 06-01, University of New Hampshire, May 12, 2006.
[15] Malinen, J., “Host AP driver for Intersil Prism2/2.5/3, hostapd, and WPA
Supplicant,” Retrieved May 20, 2006, http://hostap.epitest.fi/
[16] Melnikov, A., “The Kerberos V5 (“GSSAPI”) SASL mechanism,” Retrieved
November 15, 2006, http://www.ietf.org/internet-drafts/draft-ietf-sasl-gssapi-
08.txt
[17] Melnikov, A. and Zeilenga, K., “Simple Authentication and Security Layer
(SASL),” RFC 4422, June 2006.
[18] Project Cyrus, Carnegie Mellon University, Retrieved November 23, 2006,
http://cyrusimap.web.cmu.edu/
[19] Replay attack. (n.d.). Computer Desktop Encyclopedia. Retrieved November 02,
2006, http://www.answers.com/topic/man-in-the-middle-attack
[20] Schneier, B. and Whiting, D., “A Performance Comparison of the Five AES
Finalists,” Third AES Candidate Conference, 2000.
[21] Simpson, W. Ed., “The Point-to-Point Protocol (PPP),” RFC 1661 July 1994.
[22] Simpson, W., “PPP Challenge Handshake Authentication Protocol (CHAP),” RFC
1994, August 1996.
[23] “The Java SASL API Programming and Deployment Guide,” Sun Microsystems,
2004, http://java.sun.com/j2se/1.5.0/docs/guide/security/sasl/sasl-refguide.html
[24] Zeilenga, K., “Anonymous Simple Authentication and Security Layer (SASL)
Mechanism,” RFC 4505, June 2006.
50
APPENDICES
51
APPENDIX A
ABBREVIATIONS AND ACRONYMS
AAA Authentication, Authorization, and Accounting [RFC 3127]
AES Advanced Encryption Standard [FIPS 197]
AK Authentication Key
CHAP Challenge Handshake Authentication Protocol [RFC 1994]
DoS Denial of Service
EAP Extensible Authentication Protocol [RFC 3748]
EAP-GTC EAP-Generic Token Card [RFC 3748]
EAP-PSK EAP-Pre-Shared Key [RFC 4764]
EAP-TLS EAP-Transport Layer Security [RFC 2716]
EAP-TLS-PSK EAP- Transport Layer Security-Pre-Shared Key
EMSK Extended Master Session Key
GSSAPI Generic Security Services Application Program Interface (also
GSS-API) [RFC 1508]
IEEE Institute of Electrical and Electronics Engineers
IMAP Internet Message Access Protocol
IP Internet Protocol
KDK Key-Derivation Key
LDAP Lightweight Directory Access Protocol
MAC Message Authentication Code, same as MIC
MIC Message Integrity Check, same as MAC (also Message
Authentication Code)
MITM Man-In-The-Middle attack
MSK Master Session Key
PAP Password Authentication Protocol
POP Post Office Protocol
PPP Point-to-Point Protocol
PRF Pseudo Random Function
PSK Pre-Shared Key
SASL Simple Authentication and Secure Layer [RFC 4422]
SMTP Simple Mail Transfer Protocol
SQL Structured Query Language
TEK Transient EAP Key
TLS Transport Layer Security [RFC 4346]
TLV Type-Length-Value
VPN Virtual Private Network
WPA Wi-Fi Protected Access
52
APPENDIX B
EXPERIMENTS/USER GUIDES
This document is written to help users to install and to use CYRUS (SASL
library) in the simplest way as well as to incorporate Extensible Authentication Protocol
(EAP) into SASL. CYRUS could be integrated with DB such as SASLdb (gdbm,
Sleepycat, ndbm), SQL (mySQL and PostgreSQL v7.2 or higher) to enable
userID/password.
B.1 Cyrus Installation
* Note that some of the following steps require users to be a root.
** If you want to have SASL file transfer application incorporating EAP, do all 10
steps. Otherwise, do only first seven steps.
Step 1 download cyrus-sasl-2.1.22
Step 2 untar cyrus-sasl-2.1.22
Step 3 cd (directory it was untarred into) i.e., cyrus-sasl-2.1.22
Step 4 ./configure
Step 5 make
Step 6 make install
Step 7 ln -s /usr/local/lib/sasl2 /usr/lib/sasl2
Step 8 untar cyrus-sasl-2.1.22-eap.tar
Step 9 replace all files include/, lib/, plugins/, and sample/
directory with files in cyrus-sasl-2.1.22-eap/ directory
Step 10 re-compile
53
B.2 Cyrus usage of ANONYMOUS mechanism with file transfer
** Server side
Step 1 open terminal
Step 2 cd cyrus-sasl-2.1.22/sample
Step 3 ./server
Now a server waits for client connection.
** Client side
Step 1 open terminal
Step 2 cd cyrus-sasl-2.1.22/sample
Step 3 ./client -m ANONYMOUS host_address
Step 4 enter user account i.e., "mkim" (from mkim@localhost)
Step 5 enter file name
After client transfers a file, it will terminate the program.
In order to use other authentication methods such as CRAM-MD5 and DIGEST-
MD5, type ./client -m method_name host_address.
B.3 Cyrus Password Setup (using sasldb)
Password setup using SASLDB v.2
Step 1 /usr/sbin/saslpasswd2 userID
Step 2 enter user password
User ID and password will be saved on /etc/sasldb2
The script, /usr/sbin/sasldblistusers2, displays all users in the
SASLDB.
Password setup using SASLDB v.1
Step 1 /usr/sbin/saslpasswd userID
Step 2 enter user password
User ID and password will be saved on /etc/sasldb
The script, /usr/sbin/sasldblistusers, displays all users in the SASLDB.
54
B.4 Add Mechanism Plugins
The following example explains how to add EAP-PSK. If you want to add other
methods, replace EAP-PSK with the method name.
Step 1 Implement the following functions in plugins/ directory:
Step 1.1 Both client/server sides: add plugin_id
i.e., static const char plugin_id[] = "$Id: eappsk.c, v
1.11 yyyy/mm/dd hh:mm:ss mel Exp $"
Step 1.2 Server sides
Step 1.2.1 initialize server mechanism - mechName_server_mech_new
i.e., static int eappsk_server_mech_new(
void *glob_context __attribute__((unused)),
sasl_server_params_t *sparams,
const char *challenge __attribute__((unused)),
unsigned challen __attribute__((unused)),
void **conn_context);
Step 1.2.2 process server mechanism - mechName_server_mech_step
i.e., static int eappsk_server_mech_step(
void *conn_context __attribute__((unused)),
sasl_server_params_t *params,
const char *clientin,
unsigned clientinlen,
const char **serverout,
unsigned *serveroutlen,
sasl_out_params_t *oparams);
Step 1.2.3 fill up server mechanism plugins information - mechName_server
plugins
i.e., static sasl_server_plug_t eappsk_server_plugins[] =
{
{
"EAPPSK", /* mech_name */
0, /* max_ssf */
SASL_SEC_NOANONYMOUS, /* security_flags */
SASL_FEAT_WANT_CLIENT_FIRST
| SASL_FEAT_ALLOWS_PROXY, /* features */
NULL, /* glob_context
*/
&eappsk_server_mech_new, /* mech_new */
55
&eappsk_server_mech_step, /* mech_step */
NULL, /* mech_dispose */
NULL, /* mech_free */
NULL, /* setpass */
NULL, /* user_query */
NULL, /* idle */
NULL, /* mech_avail */
NULL /* spare */
}
};
Step 1.2.4 initialize server mechanism plugin - mechName_server_
plug_init
i.e., int eappsk_server_plug_init(
const sasl_utils_t *utils,
int maxversion,
int *out_version,
sasl_server_plug_t **pluglist,
int *plugcount);
Step 1.2.5 de-initialize server mechanism - mechName_server_mech
_dispose
Step 1.2.6 other functions: mechName_server_mech_free,
mechName_server_mech_avail
Step 1.3 Client side
Step 1.3.1 initialize client mechanism - mechName_client_mech_new
i.e., static int eappsk_client_mech_new(
void *glob_context__attribute__((unused)),
sasl_client_params_t *params,
void **conn_context);
Step 1.3.2 process client mechanism - mechName_server_mech_step
i.e., static int eappsk_client_mech_step(
void *conn_context,
sasl_client_params_t *params,
const char *serverin __attribute__((unused)),
unsigned serverinlen __attribute__((unused)),
sasl_interact_t **prompt_need,
const char **clientout,
unsigned *clientoutlen,
sasl_out_params_t *oparams);
56
Step 1.3.3 fill up client mechanism plugins information - mechName_clietn
plugins
i.e., static sasl_client_plug_t eappsk_client_plugins[] =
{
{
"EAPPSK", /* mech_name */
0, /* max_ssf */
SASL_SEC_NOANONYMOUS, /* security_flags */
SASL_FEAT_WANT_CLIENT_FIRST
| SASL_FEAT_ALLOWS_PROXY,/* features */
NULL, /* required_prompts
*/
NULL, /* glob_context */
&eappsk_client_mech_new, /* mech_new */
&eappsk_client_mech_step, /* mech_step */
&eappsk_client_mech_dispose, /* mech_dispose */
NULL, /* mech_free */
NULL, /* idle */
NULL, /* spare */
NULL /* spare */
}
};
Step 1.3.4 initialize client mechanism plugin - mechName_client_plug_
init
i.e., int eappsk_client_plug_init(sasl_utils_t *utils,
int maxversion,
int *out_version,
sasl_client_plug_t **pluglist,
int *plugcount);
Step 1.3.5 de-initialize client mechanism - mechName_client_mech_
dispose
Step 1.3.6 other function: mechName_client_mech_free
Step 2 Call the following functions in application codes
Step 2.1 Server side
Step 2.1.1 go to the line sasl_server_init() is called
Step 2.1.2 call the fuction sasl_server_add_plugin()
i.e., sasl_server_add_plugin("EAPPSK",
&eappsk_server_plug_init);
57
Step 2.1.3 include the new mechanism
i.e., #include "../plugins/eappsk.c"
Step 2.2 Client side: Software engineers must call the following functions in
application codes where locates in the directory sample/
Step 2.2.1 go to the line sasl_client_init() is called
Step 2.2.2 call the fuction sasl_client_add_plugin()
i.e., sasl_client_add_plugin("EAPPSK",
&eappsk_client_plug_init);
Step 2.2.3 include the new mechanism
i.e., #include "../plugins/eappsk.c"
Step 3 Modify the file configure in Cyrus directory
Step 3.1 search "--enable-plain"
Step 3.2 add the following code segment before the line you found
############### EAPPSK ############################
# Check whether --enable-eappsk or --disable-eappsk
was given.
if test "${enable_eappsk+set}" = set; then
enableval="$enable_eappsk"
eappsk=$enableval
else
eappsk=yes
fi;
EAPPAK_LIBS=""
if test "$eappsk" != no; then
if test "$cmu_have_crypt" = yes; then
EAPPSK_LIBS=$LIB_CRYPT
fi
fi
echo "$as_me:$LINENO: checking EAPPSK" >&5
echo $ECHO_N "checking EAPPSK... $ECHO_C" >&6
if test "$eappsk" != no; then
echo "$as_me:$LINENO: result: enabled" >&5
58
echo "${ECHO_T}enabled" >&6
SASL_MECHS="$SASL_MECHS libeappsk.la"
if test "$enable_static" = yes; then
SASL_STATIC_OBJS="$SASL_STATIC_OBJS eap-psk.o"
SASL_STATIC_SRCS="$SASL_STATIC_SRCS
../plugins/eap-psk.c"
cat >>confdefs.h <<\_ACEOF
#define STATIC_EAPPSK
_ACEOF
fi
else
echo "$as_me:$LINENO: result: disabled" >&5
echo "${ECHO_T}disabled" >&6
fi
####################################################
Step 4 Add new mechanisms on the file, Makefile.am, in the directory
plugins/
Step 5 Make sure that you re-compile for all the changes
Step 6 Make sure that the directory /usr/lib/sasl2/ contains the new
mechanism library
i.e., locate libeappsk.la
locate libeappsk.so
59
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