On Fri, 2005-02-04 at 12:07 +1000, Tim Fairchild wrote:

> Then something like "my silly old dog has too many fleas"
> 
> msodh2mf
> 
> is pretty safe by those definitions, and is easily improved like
> 
> m50d#2mf

Yes, pretty hard to guess. Of course it also depends on the usage of the
password. For example if someone gets a hold of the ciphertext used by
this password and the encryption method is weak, then the password can
be obtained by brute force.

For example the traditional Unix password encryption uses a 56 bit
hashing algorithm which takes an 8 character (7 bits per character)
password and generates a 13 character hashcode. Authentication is
handled by taking a password and generating the hashcode and comparing
them.  If they match, then the password is correct. With a 56 bit
hashing algorithm you can take run through all password combinations in
a matter of a few days with sufficient processing power.

With a longer password and a strong hashing scheme (say MD5), it takes
considerably longer to find the password via a brute force method. For
every additional bit of password length, it takes twice as long generate
all the combinations of passwords. So if it takes 2 days for an 8
character password (7 bits per character), it would take 128 times
longer (2 ** 7) for a 9 character password which is 256 days.

Given the long time it takes for a brute force attack for long passwords
even if you have the ciphertext, password cracking systems resort to
heuristic methods to find likely passwords (e.g. dictionary words, pet
names, spouse names, etc) If you use passwords like that, a cracking
program can find them in at most a few minutes.
-- 
Smoot Carl-Mitchell
System/Network Architect
email: [EMAIL PROTECTED]
cell: +1 602 421 9005
home: +1 480 922 7313

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