Xirrus Wireless LAN Array
XS-3900, XS-3700, XS-3500, WFX-
3900, WFX-3700, WFX 3500, XS4,
XS8, XS16
Security Policy
Document Version 1.1
Xirrus
December 14, 2007
May be reproduced only in its original entirety (without revision)
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TABLE OF CONTENTS
1. MODULE OVERVIEW .......................................................................................................................... 3
2. SECURITY LEVEL............................................................................................................................... 15
3. MODES OF OPERATION.................................................................................................................... 16
4. IMPLEMENTING FIPS SECURITY .................................................................................................. 18
TO IMPLEMENT FIPS 140-2, LEVEL 2 USING WMI ................................................................................... 18
TO CHECK IF AN ARRAY IS IN FIPS MODE:................................................................................................ 22
TO IMPLEMENT FIPS 140-2, LEVEL 2 USING CLI: .................................................................................... 22
5. PORTS AND INTERFACES ................................................................................................................ 23
6. IDENTIFICATION AND AUTHENTICATION POLICY .............................................................. 23
7. ACCESS CONTROL POLICY ............................................................................................................ 25
ROLES AND SERVICES............................................................................................................................... 25
DEFINITION OF CRITICAL SECURITY PARAMETERS (CSPS)....................................................................... 26
8. OPERATIONAL ENVIRONMENT .................................................................................................... 27
9. SECURITY RULES.............................................................................................................................. 27
10. PHYSICAL SECURITY POLICY ..................................................................................................... 28
PHYSICAL SECURITY MECHANISMS.......................................................................................................... 28
OPERATOR REQUIRED ACTIONS ............................................................................................................... 28
11. MITIGATION OF OTHER ATTACKS POLICY............................................................................ 28
12. DEFINITIONS AND ACRONYMS ................................................................................................... 28
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1. Module Overview
The Xirrus Wireless LAN Array (Models XS-3900, XS-3700, XS-3500, WFX-3900,
WFX-3700, WFX-3500, XS16, XS8, and XS4) is a multi-chip standalone cryptographic
module whose cryptographic boundary is a hard, opaque commercial grade plastic
enclosure. The primary purpose for this device is to provide data security for wireless
Internet Protocol (IP) traffic. The device provides status output via LEDs and a user
console. The device provides network interfaces for data input, data output, status output,
and command input. The device also provides these services via Wi-Fi. The diagram
below illustrates the supported interfaces as well as defining the cryptographic boundary.
Figure 1 – Image of the Xirrus Access Point XS-3900 and XS16 – Top View
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Figure 2 – Image of the Xirrus Access Point XS-3900 and XS16 – Bottom View
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Figure 3 – Image of the Xirrus Access Point XS-3700 and XS8 – Top View
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Figure 4 – Image of the Xirrus Access Point XS-3700 and XS8 – Bottom View
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Figure 5 – Image of the Xirrus Access Point XS-3500 and XS4 - Top View
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Figure 6 – Image of the Xirrus Access Point XS-3500 and XS4 - Bottom View
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Figure 7 – Image of the Xirrus Access Point WFX-3900, Top View
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Figure 8 – Image of the Xirrus Access Point WFX-3900, Top View
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Figure 9 – Image of the Xirrus Access Point WFX-3700, Top View
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Figure 10 – Image of the Xirrus Access Point WFX-3700, Bottom View
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Figure 11 – Image of the Xirrus Access Point WFX-3400, Top View
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Figure 12 – Image of the Xirrus Access Point WFX-3500, Bottom View
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All Xirrus arrays are derived from the same base design. The Array Controller used in
all models is the same PCB with different build options for power and radio support. The
radios used in each model are of the same design and only differ in number of radios
used. The 3900 models use 16 radios, the 3800 models use 8 radios and the 3500 models
use 4 radios. The same firmware is used in all models. The difference between the XS
models and the WFX models is in the branding of the hardware and the software. There
are no functional differences between the model families.
Table 1 – Part Number Table
Model Part Number Version Firmware
XS-3900 190-0001-001 B1 3.2-0477
190-0001-002 B1 3.2-0477
190-0001-003 B1 3.2-0477
190-0001-004 B1 3.2-0477
XS-3700 190-0005-001 B1 3.2-0477
190-0005-002 B1 3.2-0477
190-0005-003 B1 3.2-0477
190-0005-004 B1 3.2-0477
XS-3500 190-0004-001 A1 3.2-0477
190-0004-003 A1 3.2-0477
WFX-3900 190-0016-001 A1 3.2-0477
WFX-3700 190-0017-001 A1 3.2-0477
WFX-3500 190-0018-001 A 3.2-0477
XS4 190-0092-001 A 3.2-0477
XS8 190-0091-001 A 3.2-0477
XS16 190-0090-001 A 3.2-0477
2. Security Level
The cryptographic module meets the overall requirements applicable to Level 2 security
of FIPS 140-2.
Table 2 - Module Security Level Specification
Security Requirements
Section
Level
Cryptographic Module
Specification
2
Module Ports and Interfaces 2
Roles, Services and
Authentication
3
Finite State Model 2
Physical Security 2
Operational Environment N/A
Cryptographic Key
Management
2
EMI/EMC 3
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Self-Tests 2
Design Assurance 2
Mitigation of Other Attacks N/A
3. Modes of Operation
Approved mode of operation
In FIPS mode, the cryptographic module only supports FIPS Approved algorithms as
follows:
• AES ECB, CBC 128-bit (encryption)
• AES CCM
• HMAC
• SHA-1
• RSA
The cryptographic module relies on the implemented deterministic random number
generator (DRNG) described below.
“NIST-Recommended Random Number Generator Based on ANSI X9.31 Appendix
A.2.4 Using the 3-Key Triple DES and AES Algorithms”
The DRNG is seeded by the module’s NDRNG (/dev/urandom).
3 ANSI X9.31 Appendix A.2.4 Using AES
Let ede*X(Y) represent the AES encryption of Y under the key *X.
For AES 128-bit key, let *K be a 128 bit key.
For AES 192-bit key, let *K be a 192 bit key.
For AES 256-bit key, let *K be a 256 bit key.
This *K is reserved only for the generation of pseudo random numbers.
Let V be a 128-bit seed value which is also kept secret, and XOR be the exclusive-or operator. Let DT be a
date/time vector which is updated on each iteration. I is a intermediate value. A vector R is generated as
follows (Note for AES implementations DT, I, and R are 128-bits each.):
I = ede *K(DT)
R = ede *K(I XOR V) and a new V is generated by V = ede*K(R Xor I).
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Non-FIPS mode of operation
In non-FIPS mode, the cryptographic module provides non-FIPS Approved algorithms as
follows:
• RC4 for encryption/decryption in TKIP and WEP
• MD5
• Software RNG (/dev/urandom)
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4. Implementing FIPS Security
Wi-Fi Arrays may be configured to satisfy the requirements for Level 2 of Federal Information
Processing Standard (FIPS) Publication 140-2. The procedure in this section lists simple steps
that must be followed exactly to implement FIPS 140-2, Level 2. The procedure includes
physical actions, and parameters that must be set in Web Management Interface (WMI) windows
in the Security section and in other sections.
To implement FIPS 140-2, Level 2 using WMI
1. Apply the supplied tamper-evident seals to the unit as indicated in the figures below. The
procedure is slightly different, depending on the model.
• Before you apply the tamper-evident seal, clean the area of any grease, dirt, or oil.
We recommend using alcohol-based cleaning pads for this.
Each seal must be applied to straddle both sides of an opening so that it will show if
an attempt has been made to open the Array.
XS-3900 or XS-3700—Apply two seals, one on either side of the Array about 180°
apart from each other, as shown. Apply a third seal to the access panel opening, as
shown. IMPORTANT: Make sure that each seal straddles a seam.
Figure 13 – Applying three tamper-evident seals to the XS-3900 or XS-3700
1
2
3
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• XS-3500—Apply two seals, one on either side of the Array about 180° apart from
each other, as shown. IMPORTANT: Make sure that each seal straddles a seam.
1
2
Figure 14 – Applying two tamper-evident seals to the XS-3500
2. Enable HTTPS using the CLI if it is not already enabled, using the following command:
Xirrus_Wi-Fi_Array(config)# https on
This allows the Web Management Interface to be used for the rest of this procedure.
HTTPS is enabled on Arrays by default.
3. Select the SSIDs/SSID Management window. Set Encryption Type to WPA2 (Figure
15). Click Modify, and then Save. Make sure that this is set for each SSID.
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Figure 15 – SSID Management Window
4. In the Security/Global Settings window, select No for TKIP Enabled and Yes for AES
Enabled. Click Apply, and then Save.
Figure 16 – Security/Global Settings Window
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5. In the Security/Management Control window, select Yes for Enable Management over
SSH. Select No for Enable Management over Telnet and for Enable Management
over IAPs. Click Apply, and then Save.
Figure 17 – Security/Management Control Window
6. In the Services/SNMP window, select No for Enable SNMP. Click Apply, and then
Save.
Figure 18 – Services/SNMP Window
7. In the IAPs/Global Settings window, select Off for Fast Roaming. Click Apply, and
then Save.
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Figure 19 – IAPs/Global Settings Screen
To check if an Array is in FIPS mode:
You may determine whether or not the Array is running in FIPS mode by verifying that the
settings described in the previous procedure are in effect.
To implement FIPS 140-2, Level 2 using CLI:
1. The following CLI command will perform all of the settings required to put the Array in
FIPS mode:
Xirrus_Wi-Fi_Array(config}# fips on
This command remembers your previous settings for FIPS-related attributes. They will
be restored if you use the fips off command.
Use the save command to save these changes to flash memory.
2. Use the fips off command if you would like to revert the FIPS settings back to the values
they had before you entered the fips on command.
Xirrus_Wi-Fi_Array(config}# fips off
Use the save command to save these changes to flash memory.
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5. Ports and Interfaces
The cryptographic module provides the following physical ports and logical
interfaces:
Model 10/100 Ethernet
Port
Gigabit
Ethernet Port
Serial Port
(RS232)
TX/RX Radio
Port
Status LEDs
XS-3900 1 2 1 16 1
XS-3700 1 2 1 8 1
XS-3500 N/A 1 1 4 1
WFX-3900 1 2 1 16 1
WFX-3700 1 2 1 8 1
WFX-3500 N/A 1 1 4 1
XS16 1 2 1 16 1
XS8 1 2 1 8 1
XS4 N/A 1 1 4 1
10/100 Ethernet Port: data input, data output, control input, status output
Gigabit Ethernet Port: data input, data output, control input, status output
Serial Port (RS232): data input, data output, control input, status output
Radio Port: data input, data output
TX/RX Radio Port: data input, data output
LEDs: status output
Power Interface: power
6. Identification and Authentication Policy
Assumption of roles
The cryptographic module shall support two distinct operator roles (User and Crypto Officer).
The Crypto Officer role shall be performed by the Administrator managing the device, and the
User role shall be performed by the wireless client using the device to send and receive data.
Table 1 - Roles and Required Identification and Authentication
Role Type of Authentication Authentication Data
Crypto Officer Identity-based operator
authentication
Password
User Identity-based operator
authentication
PSK
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Table 2 – Strengths of Authentication Mechanisms
Authentication Mechanism Strength of Mechanism
Password Passwords are at least 5 characters long, with
94 characters available. Therefore, the
probability that a random attempt will succeed
or a false acceptance will occur is
1/7,339,040,224 which is less than
1/1,000,000.
To exceed 1 in 100,000 probability of a
successful random attempt during a 1-minute
period, 73391 (1233 per second) attempts
would have to be executed. This is not feasible
from a standpoint of device capabilities.
PSK 802.11i Pre-Shared Key (PSK) is 32 bytes (256
bits) long, therefore there are 2256
possibilities
for a PSK. This means that exceeding 1 in 100,
000 probability of a successful random attempt
during a 1-minute period is not feasible from a
device capabilities standpoint.
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7. Access Control Policy
Roles and Services
Table 3 – Services Authorized for Roles
Role Authorized Services
User:
This role shall provide all
of the services necessary
for the secure transport of
data over Wi-Fi.
• 802.11i with PSK: This service allows a user to authenticate
and send/receive data in a secure manner using 802.11i PSK
mode.
Crypto Officer:
This role shall provide all
services that are necessary
to manage the
cryptographic module in a
secure fashion.
• Zeroize: This service allows an administrator to zeroize all
the keys and CSPs.
• Update Firmware: This service allows an administrator to
load new firmware into the module.
• Show Status: This service allows an administrator to display
the module’s current configuration. This information will
also include operational statistics such as the number of
users that are currently logged onto the access point.
• Manage Configuration: This service allows an administrator
to change configuration settings within the module such as
establishing SSIDs, modifying usage of power, turning
radios on/off, adding new users, and enter PSK.
Unauthenticated Services:
The Xirrus Access Point supports the following unauthenticated services:
• Self-tests: This service executes the suite of self-tests required by FIPS 140-2.
Table 5 - Specification of Service Inputs & Outputs
Service Control Input Data Input Data Output Status Output
802.11i with
PSK
Header info. Key generation
parameters, data
Key, data Success/fail
Zeroize Header info. None None Success/fail
Update
Firmware
Header info. New firmware
image
None Success/fail
Show Status Header info. None Configuration
Status
Success/fail
Manage
Configuration
Header info. Configuration
Parameters
None Success/fail
Self-Tests Header info. Configuration
Parameters
None Success/fail
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Definition of Critical Security Parameters (CSPs)
The following are CSPs contained in the module:
Crypto Officer Password: This is an operator defined password (at least 5 characters long) that
allows an administrator to log into the module. The password is stored on EEPROM as MD5
one-way hash. Can be zeroized by resetting the unit to defaults which will reset the password to
default one.
802.11i Pre-Shared Key (PSK): This is a key used when deriving 802.11i AES session key. This
key as entered as a passphrase by operator via SSH or HTTPS and is stored on EEPROM in RC4
encrypted form. It can be zeroized by resetting the unit to defaults which will reset the
passphrase to default one.
802.11i AES Session Key: This is an AES key used to encrypt and decrypt data packets. This
key is derived from 802.11i PSK. It is stored in RAM and can be zeroized by resetting the unit
to defaults.
TLS Session Keys: These keys are used by the module to set up encrypted TLS tunnels.
SSH Session Keys: These keys are used by the module to set up encrypted SSHv2 tunnels.
Firmware HMAC Key: The key used to validate new and existing firmware.
Table 6 – CSP Access Rights within Roles & Services
Role Service Cryptographic Keys and CSPs Access
CO User
X 802.11i with PSK Derive 802.11i AES Session Key using 802.11i PSK.
Encrypt/decrypt data traffic using 802.11i AES Session
Key.
X Zeroize Login using Crypto Officer's password to obtain access
to 'Zeroize' service. Reset 802.11i PSK and Crypto
Officer password to defaults, zeroize 802.11i AES
Session Key, zeroize TSL and SSH keys, and zeroize
Firmware HMAC key.
X Update Firmware Login using Crypto Officer's password to obtain access
to 'Update Firmware' service and Firmware HMAC
key.
X Show Status None
X Manage
Configuration
Login using Crypto Officer's password to obtain access
to 'Manage Configuration' service. Change 802.11i
PSK and Crypto Officer password values. Generate
TLS session keys and SSH session keys.
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8. Operational Environment
The FIPS 140-2 Area 6 Operational Environment requirements are not applicable because the
Xirrus Access Point does not contain a modifiable operational environment.
9. Security Rules
The Xirrus Access Point’s design corresponds to the cryptographic module’s security rules. This
section documents the security rules enforced by the cryptographic module to implement the
security requirements of this FIPS 140-2 Level 2 module.
1. The cryptographic module shall provide two distinct operator roles. These are the User
role and the Crypto Officer role.
2. The cryptographic module shall provide identity-based authentication.
3. When the module has not been placed in a valid role, the operator shall not have access to
any cryptographic services.
4. The cryptographic module shall encrypt/decrypt data using the AES algorithm.
5. The cryptographic module shall perform the following tests:
A. Power up Self-Tests:
1. Cryptographic algorithm tests:
a. AES Known Answer Test
b. DRNG Known Answer Test
c. RSA Known Answer Test
2. Firmware Integrity Test (HMAC-SHA1)
B. Conditional Self-Tests:
1. Continuous DRNG test (128-bit)
2. Continuous NDRNG test (/dev/urandom)
3. Firmware Load Test (HMAC-SHA1)
6. At any time the cryptographic module is in an idle state, the operator shall be capable of
commanding the module to perform the power-up self-test.
7. Seeds used for DRNG are generated by Linux /dev/urandom.
8. Data output shall be inhibited during key generation, self-tests, zeroization, and error
states.
9. Status information shall not contain CSPs or sensitive data that if misused could lead to a
compromise of the module.
10. The module shall support concurrent users.
11. The module conforms to FCC Class A and B.
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10. Physical Security Policy
Physical Security Mechanisms
The multi-chip standalone cryptographic module includes the following physical security
mechanisms:
• Production-grade components and production-grade opaque enclosure
• Tamper evident seals.
Operator Required Actions
The operator is recommended to periodically inspect tamper evident seals.
Table 7 – Inspection/Testing of Physical Security Mechanisms
Physical Security
Mechanisms
Recommended Frequency of
Inspection/Test
Inspection/Test Guidance
Details
Tamper Evident Seals 1 month Instructions for the
recommended inspections are
located in the operator’s
manual.
11. Mitigation of Other Attacks Policy
The module has not been designed to mitigate attacks that are outside of the scope of FIPS 140-
2.
Table 8 – Mitigation of Other Attacks
Other Attacks Mitigation Mechanism Specific Limitations
N/A N/A N/A
12. Definitions and Acronyms
AES Advanced Encryption Standard
DRNG Deterministic Random Number Generator
TKIP Temporal Key Integrity Protocol
RC4 ARCFOUR – a stream cipher for IP
WEP Wired Equivalent Privacy
Wi-Fi IEEE 802.11 wireless networks