Choosing a Good Password
Why do I have to choose a good password?
Weak passwords are easily broken by intruders with dictionary-based
password cracking programs. This is a problem for system security, and
thus is not allowed. Accounts with weak passwords will be closed. More
information about user security is available.
How do I choose a good account password?
NOTE: Your UNIX password and your Windows password are
not stored in the same place. For your protection, we
highly recommend that you do NOT share
passwords between your UNIX and Windows accounts. Doing so can
jeopardize your account security.
UNIX passwords must be at least 6 characters long. Windows passwords
must be at least 8 characters long.
Passwords should contain 3 of the 4 character types:
- UPPERCASE letters: A-Z
- lowercase letters: a-z
- numbers: 0-9
- symbols: ~`!@#$%^&*()_-+={[}]|\:;"'<,>.?/
Do not use all letters or all numbers, and do not use a
dictionary word in any language or a permutation of such.
Dictionaries of all languages are available online, and not all hackers
speak English. Also avoid using your name, account name, common names of
people or places, technical jargon, repeating sequences and keyboard
sequences.
Do not use a well-known phrase to generate a password.
This approach may be vulnerable to a dictionary attack using dictionaries
compiled from popular media phrases. A paper entitled
Human Selection of Mnemonic Phrase-Based Passwords,
by C. Kuo, S. Romanosky, and L. Cranor of Carnegie Mellon
University’s CUPS Laboratory
explores this potential threat.
Examples:
Good Passwords (but don't use these, make your own!)
- Mhtiasp! Based on “My
home town is
a small
place!”
- Mh714sp! Based on “My
home 7own 1s
4 small
place!”
- .-Mcismf--.
Based on “.-Morse
code is so
much fun --.”
- 2Tamlamt Based on line 2 of
Shakespeare’s Sonnet #18 “Thou
art more lovely
and more
temperate”
Bad Passwords
- mypasswo - Obviously plain-text based
(“mypassword”)
- kathy5 - Name-based
- ........ - Repeating sequence
- abcabc - Repeating sequence
- dr1v3way - Word-based with common
letter/number substitution
- gandalf1 - Based on the name of a character from
The Hobbit
- triskeli - Based on a word from Star Trek
(“triskelion”)
- ykmfptd! - Based on a quote from the movie
Princess Bride: “My name is Inigo Montoya.
You killed my
father. Prepare to
die!”
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