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Why shouldn't a colon (:) be used in a secure password?

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weigoldk

MIS
Jan 12, 2001
249
US
Several sites that discuss tips for secure passwords say NOT to use the colon :)) in a secure password. Does anyone have an explanation?
 
Never heard this. Doesn't mean anything special in binary (ascii ":" is A3, which is 10100011).

Chip H.
 
I think it is no security reason, but in UNIX i think in the File /etc/password and /etc/shadow the colon may be used as a seperator. Perhaps you are missunderstanding something.
hnd
hasso55@yahoo.com

 
Or there might be a program reason for it. iSeriesCodePoet
IBM iSeries (AS/400) Programmer
[pc2]
 
This is just one of many examples I found on the net--notice number 3.
A secure password
1.is at least six but no longer than eight characters
2. contains numbers, punctuation and upper- and lower-case letters
3. does not contain a colon :))
4. does not contain your user ID or anyone's name, either forwards or reversed
5. does not contain any string of characters associated with you (your licence plate, your telephone number, etc.), either forwards or reversed
6. is not a word that can be found in any dictionary (English, French, Spanish, biographical, specialized, etc.), either forwards or reversed
 
To put some meat into this discussion, let me tell you why I decided to post the question.

1. I've been asked to put on a security discussion for my company. I don't want to put something into the discussion that I can't justify (ie not using a colon in a password), yet since I've seen it so may times, I don't want to leave it out if it has merit.

2. There is another character that I've heard is VERY secure in NT passwords. I once attended an NT security conference that said the password crackers at that time could not crack a password if this particular character was used first. I was wondering if there was something "magic" about a colon that made a password equally unsecure. Since the security conference was several years ago, I'm sure the crackers have discovered a way to crack the once very secure character.
 
I believe some security management applications use colon delimited files to manage security. Using a colon would, of course, confuse these apps.
 
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