| Creating Good Passwords |
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Copyright 1999 -- Light Source Software Labs, Inc. -- All Rights Reserved
Author: Kevin W. Wall |
| The author grants permission to everyone permission to use this document in part or in whole on any web page or other publication so as long as all of the copyright information (above) and this notice is included in its entirety. |
(NOTE: On most versions of Microsoft Windows, unless you are certain that the 16-byte "Lan Manager hash" is not being sent as part of an "Windows password challenge / response" exchange when you enter your password, you'd best keep as close to the maximum of 14 characters as you can. For details on how easy it is to crack short passwords in many Windows environments, see the L0pht Heavy Industries site.)
(NOTE: It's okay to guard your passwords to other systems in an encrypted file. For Windows-based operating systemss, use something like "Password Safe" which is freely available from Counterpane Systems. Of course, make certain that you secure those passwords with a good pass phrase.)
<word1><s><word2>
Next take the digits ("#" below) and insert them in an arbitrary position in the password:<w#ord1><s><wor#d2>
(All right, if you must, you can place these random digits at the front and/or back.) Alternately, rather than adding digits, you can map one or more letters to digits. If you do this in the following way, you may find it easier to remember.
Letter-to-digit Transformation
(*)
(...or "73tt3r-t0-d191t Tr4n5f0rm4t10n")
| These Letters | Map to these digits | Hints | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ---------------- | ---------------------- | ----------------------------------------------------------------- | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Note that this isn't as good as using arbitrarily-placed random digits because some hybrid dictionary attacks take these into account, but it is much better than only placing a digit or two at the beginning or end.
In general, the way to remember these transformation is that the letters are supposed to resemble (even if it is in some contorted way) the digits wto which they map. Consider them a memory aid for the password-impaired, a group in which I consider myself a member ;-).
Finally, change the case (upper-to-lower or lower-to-upper) of at least one of the letters (but NOT the first one!!!) so that all the letters are not the same case.
Some GOOD Examples (**)
| <word1> | <s> | <word2> | Comment |
| ---------- | ---- | ---------- | ------------ |
| nail | # | hicup | n4ils#h1cUp |
| egg | > | road | e99>r0ad |
| walk | % | gentle | w41k%gentle |
Some BAD Examples
| <word1> | <s> | <word2> | Result | The Problem |
| --------- | ---- | --------- | ------ | -------------- |
| cat | - | dog | cat-dog1
cat-d0g 3cat-dog |
"cat" & "dog" are not unrelated enough. |
| soccer | & | chris | s0cc3r&chr15 | Although the words "soccer" and "chris" are not related, this violates the rule of not using words that are personal in nature. (Chris is my son's name and he happens to like soccer.) |
| green | | | red | gr33n|r3d
green0|red1 |
The colors "green" and "red" are too closely related. (Not only are they both colors, but they often are associated together; e.g., Christmas colors.) |
Variation 1:
Transform a short phrase into pseudo-English (or whatever
your native tongue happens to be) and
translate that into the password.
Some GOOD Examples
| Password | Comment |
| ----------- | ------------------------- |
| Wh0RU?!m3 | Phrase was "Who are you? Not me". The o has been transformed to 0, 'are' becomes 'R', 'you' becomes 'U'. We use the standard punctuation mark '?' to end the first part. The '!' is computer geek jargon for 'not'. Finally, in the 'me' we transformed the letter 'e' to a '3' (according to our standard letter-to-digit transformations). |
| w0n6y1!? | The original phrase was "one by one". It was then transformed to "won by 1" and the letter-to-digit transformation was then used on the "o" and "b". The last step was to add two punctuation characters. (Two characters were added to make it eight characters long, in order to increase its resistance to brute force attacks.) |
| EZas3.14! | This phrase is "easy as pi(e)!" |
| MK$4family | This phrase is "make (MK) money ($) for family". |
Some BAD Examples
| Password | Comment |
| ----------- | ---------------------------------------- |
| make$$$$ | Must be a $ales guy! This password is a little on the weak side. |
| hello:-) | Seems a little obvious given the popularity of emoticons. |
| 2B||!2b? | Original phrase was "to be or not to be". The '?' was added, but seems suitable (given the rest of the phrase)... plus it adds to the somewhat to security. However, this is listed as a "bad" example rather than a good one because there are just too many geeks out there that think this is just too clever to pass up. (You know who you are!) In the past twenty years, I recall seeing this or some variation thereof at least three separate times. |
Variation 2:
(better than Variation 1) - Choose the first
character of a short
sentence, mix in some upper-case and
puntuation and transform some letters to digits.
Some GOOD Examples
| Password | Comment |
| ----------- | ------------------------------- |
| Tifwyahf. | Phrase is "Time is fun when you are having flies." Of course, this would be a poor selection for me, as this is one of my favorite quips, and thus could be considered in the category of personal information. |
| B?Wdnnsb! | Phrase is "Badges? We don't need no stinking badges!" Safe, unless it's a well-known fact that Treasure of the Sierra Madre was your favorite film, in which case this should be considered personal information, and thus you shouldn't use it. |
| Tthc,tws,Tt0mt | As long as someone doesn't know you're a fan of Lewis Carroll, this should be fairly secure. BTW, the phrase is "The time has come the walrus said, to talk of many things" (with the 'o' in 'of' transformed to zero just for good measure). [Lewis Carroll, Through the Looking-Glass] |
| 1tgpRi! | The phrase is "I think good passwords are important!". Note besides the standard letter-to-digit transformation of 'I' to '1', this also employs Variation 1 (above) by using an 'R' for 'are' rather the using 'a'. |
| Password | Comment |
| ----------- | ------------------------------ |
| AFAIK | Aside from being too short, "as far as I know" is too often just written as "AFAIK" so it's likely to be in a cracker dictionary somewhere. The same goes for other popular Internet acronyms, such as OTOH, ROFL, BTW, and so on. |
| bbroygbvgw | The color coding on resistors: black, brown, red, orange, yellow, green, blue, violet, gray, white. The phrase might be considered sexual harassment were I to repeat it. If you really want to know what it stands for, talk to an EE Geek. ;-) |
| RoyG.Biv | The colors of the spectrum: Red, Orange, Yellow, Green, Blue, Indigo, Violet. Possibly in a cracker dictionary, especially one that targets techno-geeks. |
| 4s&7ya | The phrase "four score and seven years ago"... possibly not as bad as others listed here (except that it is too short), but this phrase is just too common to be really secure. Others to avoid are common ones such as "The quick brown fox jumped over the lazy dogs", "Now is the time for all good men to come to the aid of their party" and other popular well-known quotations. On the other hand, my guess is that for most of you, "nittfagm2c2taotp" ("Now is the time...") is more secure than any password you've used before. However you, probably aren't going to want to type all that, especially when blinded -- remember these characters generally won't echo when using them for a password! |
Some GOOD Examples
| Password | Pattern / Comment |
| ----------- | ----------------------------- |
| .mu9l,ji | Start at '.' and circle clockwise skipping one character until you reach the starting character, and make second clockwise circle starting at the character to the left of the original starting character. Continue until you have eight or more characters. |
| zvm/159\ | Start on the bottom row, on the left-most side (z). Then skip two characters (that is, type every third character) until you reach the end of the row. Then go to top row, on the left side (1) and skip three characters (that is, type every fourth character) until you reach the end of the top row. |
| Password | Comment |
| ----------- | ---------------------------------------------- |
| asdfghjk | Should be obvious what's wrong here! |
| abcdefgh | Again, obvious! |
| aaaaaaaa | Obvious! |
| qwerty | Obvious! |
| aabbccdd | Obvious! |
| a1b2c3d4 | Obvious! |
| abcd1234 | Obvious! |
Many of these are likely to be in a good cracker dictionary, or be crackable via hybrid dictionary attacks, for example, by repeating certain key patterns.
Some GOOD Examples
| Original Word | Resulting Password | Comment |
| ---------------- | -------------------- | ------------------------- |
| 1Bakery | 2Nslru | Hands are moved to type the character to the right of each original character. |
| whitehouse | {snkgdnlxd} | Has prepended and appended { and } respectively, but otherwise password is typed with hands moved from the home row to the bottom row. |
| Original Word | Resulting Password | Comment |
| ---------------- | -------------------- | ------------------------- |
| wafer! | esgrt@ | This password is too short. Also, for me, "WAFER" would be considered personal information: it's the name of the product I work on. |