In general it is easier to remember a pass phrase than to remember a cryptic password of equivalent strength.
For example the cryptic password
'7dKgN4yD7z' is harder to remember than the pass phrase
'then swish job fixed Won't Betray'.
Your mind will quickly group the pass phrase into two word sets (e.g.
then swish,
job fixed,
Won't Betray) thereby making it much easier to remember.
Conversely it is difficult for most people to remember long cryptic passwords since it is not easy for the mind to group the password into little chunks to remember.
Trying to pick a password or pass phrase on your own is generally insecure because people tend to follow predictable patterns when choosing passwords.
These patterns are easy to replicate in a computer thereby making it much easier to determine a persons password or pass phrase.
However a computer generated password or pass phrase does not suffer from these same biases and therefore produces much more random and therefore secure passwords and pass phrases.
The relative strength of a password or pass phrase is dependent upon the number of possible permutations and the number of biases that can be used to infer a smaller set of possible permutations.
By choosing a completely random password or pass phrase from a large set of possible permutations the number of biases are kept to a minimum and therefore brute force attacks on the password or pass phrase become infeasible.
The pass phrases generated by this program are produced from a large set of specially selected possible words. A 6 word pass phrase generated by this program will have more than 13,716,727,953,760,776,108 possible permutations.
As a comparison, an 8 character password using upper case (A-Z), lower case (a-z), and digits (0-9) will only have slightly more than 218,340,105,584,893 possible permutations.
Below are some example passwords and pass phrases and their relative strength in terms of the number of permutations:
| s7qhejt0 | 2,821,109,907,456 |
| false did find Brasil | 5,730,163,538,176 |
| k3j5k3La | 218,340,105,584,893 |
| then swish job fixed Won't Betray | 13,716,727,953,760,776,108 |
| u5mf9c6gp2ia65be | 7,958,661,109,946,323,179,154,555 |
Below are some example computers and how many operations
per second that they can process:
| Cray XT5 | 1,759,000,000,000,000 |
| Tianhe-1A | 2,507,000,000,000,000 |
| Sequoia (not yet operational) | 20,000,000,000,000,000 |