User's Manual

Date Code 20050615 Instruction Manual SEL-3022 Transceiver
Wireless Operator Interface Security
The SEL Security Application
C.13
Cryptographic Manual—Do Not Copy
1.83 • 10
63
years, on average, to guess both the authentication key and the encryption
key values. The analysis just described suggests that it is statistically impossible to
launch a key guessing attack against the SEL-3022 device that would result in
compromise of the system.
Even if someone were to steal a maintenance PC with the wireless interface encryption
and authentication keys programmed and saved on the PC hard drive, an attacker would
have to crack the SEL-3022 connection password to use the stolen computer to
successfully authenticate with the SEL-3022. To launch a password guessing attack, an
attacker would have to repeatedly send an initial session request frame and enter the
password guess into the SEL-5809 Settings Software dialog box.
If the entered password value is incorrect, the SEL-3022 terminates the session
authentication dialog after receiving Frame 3 of the authentication dialog (see
Figure C.5 on page C.15 and the discussion Connection Authentication and Session
Replay Protection on page C.14). If the authentication dialog fails at any point, the
SEL-3022 performs a timeout of the wireless operator interface and refuses any session
connection requests for five seconds. This limits the rate of a password guessing attack
to one guess per five seconds.
The SEL-3022 accepts password entries between 6 and 80 characters in length. These
passwords can contain all 96 printable ASCII characters (including the Space
character). If we assume that the security officer has programmed strong passwords
into the SEL-3022, an attacker would not be able to use a typical password guessing
attack dictionary to limit the number of required password guesses. In this case, all
possible password values would be equally likely and the attacker would have to
launch a brute-force password guessing attack by sending all possible password values
to the SEL-3022, one at a time. Tabl e C.1 shows the number of potential password
values (i.e., the maximum number of guesses that an attacker will have to make) and
the average number of years required to launch a successful brute-force password
guessing attack on the SEL-3022 as a function of the length of your programmed
password value. The value representing the average number of years required to
successfully guess the SEL-3022 connection password was derived under the
assumption that all potential password values are equally probable (i.e., you do not
program a password value that is likely to be in an attack dictionary). Such strong
passwords do not form a word, slang term, or other meaningful value. A strong
password also contains a mixture of alphanumeric characters (numbers and uppercase
and lowercase letters) and non-alphanumeric characters (punctuation characters,
backslash, space, etc.).
Table C.1 Number of Years Required to Guess an SEL-3022 Password
Password
Length
Number of Possible
Password Values
Average Number of Years Required to
Guess the Password (Assuming Strong
Password Choice)
67.91 • 10
11
6.27 • 10
4
77.59 • 10
13
6.02 • 10
6
87.29 • 10
15
5.78 • 10
8
Preliminary Copy