nwrickert
sand groper
Premium,MVM
join:2004-09-04
Geneva, IL
 ·AT&T U-Verse
 ·AT&T Midwest
| reply to Jack Morgan
Re: Passphrase strength, is this right?
Your computation is correct, assuming a dictionary attack. If the words are chosen randomly from the dictionary, your 5 word phrase corresponds to around 63 bits of entropy. If your choice of words is non-random, the amount of entropy could be considerably less.
The 5 million tries per second might be slow. Depending on what you are protecting, an attacker might be willing to use considerably more compute power. If your encryption needs to be long lasting, then you need to protect against future computer speeds, not just todays speeds.
If the encryption is for something like WPA, then some information about the key is given out in the observable transmissions, which can be used to speed up cracking the encryption.
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