"not more than 2 identical characters in a row"? WTF? Stop with this nonsense.
This is OT, but there's an interesting snippet in "The Secret Life of Bletchley Park" [1] about decoding Enigma messages used by the Italian Navy in the Med.
One of the female operators had a set of messages from one Italian operator who sent a message once a week on a regular basis. They had determined that the first letter was an 'L'. She looked at the keyboard, saw that 'L' was neatly placed under the right hand and guessed that he was sending a test message consisting of nothing but 'L's tapped out in quick succession. Voila! She hit the jackpot.
From this insight, all dial wirings and movements of the Italian machines could be quickly deduced.
So, repetitive plain text can be a security issue.
This is OT, but there's an interesting snippet in "The Secret Life of Bletchley Park" [1] about decoding Enigma messages used by the Italian Navy in the Med.
One of the female operators had a set of messages from one Italian operator who sent a message once a week on a regular basis. They had determined that the first letter was an 'L'. She looked at the keyboard, saw that 'L' was neatly placed under the right hand and guessed that he was sending a test message consisting of nothing but 'L's tapped out in quick succession. Voila! She hit the jackpot.
From this insight, all dial wirings and movements of the Italian machines could be quickly deduced.
So, repetitive plain text can be a security issue.
[1] http://www.amazon.com/The-Secret-Life-Bletchley-Park/dp/1845...