Passphrase generation

Hi,
I am wanting to learn how to generate a passphrase that is at least as 
strong as the IDEA algorithm.  I have looked several other places on the 
web for an answer to this, but they all had different things to say that 
didn't add up (no pun intended :).
The IDEA algorithm it seems is 2^128 =  3.402823669209e+38 = 16 bytes 
(charactors).
The charactor count seems kinda small (I am presuming the 16 charactors are 
truely random).
Indeed, 128(ASCII charactor set)^16 =  5.192296858535e+33.
Is my thinking right here?
Is it better to do this- 94(printable ASCII set)^20 =  2.901062411315e+39, 
yielding 20 charactors?

Also, if you come up with a phrase and put enough (perhaps 5 or 6) ASCII 
nonsense in there for it not to be in any crack dictionaries, how random is 
that?  Is it only as random as the extra charactors you put in?  How would 
you calculate that?

Also, how many charactors do you have to add of a set to add its 
permulations (i.e. Does gibber&sh add all ASCII symbols to the equation)?

Thanks, Internaut

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Internaut <unde0275@frank.mtsu.edu> writes:
> Hi,
> I am wanting to learn how to generate a passphrase that is at least as 
> strong as the IDEA algorithm.  I have looked several other places on the 
> web for an answer to this, but they all had different things to say that 
> didn't add up (no pun intended :).

Chech out the cannonical passphrase FAQ:
http://www.stack.nl/~galactus/remailers/passphrase-faq.html

This one has some quick reminders of what to do and not to do
http://www.encryption.com/pphrase.htm

Bottom line, totally random ASCII will have lots of bits per
character, but english has about 1.2 bits per character. Misspellings
can add to that, depending on the extent of mutillation . Combining
certain words can make your passphrase weaker (such as "To be or not
to be," "This is my passphrase," etc.).

HTH,
Jer

"standing on top of the world/ never knew how you never could/ never knew
 why you never could live/ innocent life that everyone did" -Wormhole

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