2 ms·
Beside the title being misleading (it's a 30-symbol password, not 30-character, as "character" implies printable ASCII to most people), the math doesn't quite m
by colanderman 14y ago
Beside the title being misleading (it's a 30-symbol password, not 30-character, as "character" implies printable ASCII to most people), the math doesn't quite make sense:
Before running, the game creates a random sequence of 30 letters chosen from S, D, F, J, K, and L, with no repeating characters. This equates to around 38 bits of entropy
So that's 6 choices for the first character, and 5 choices for each of the next 29 gives us log2(6*5^29) =~ 70 bits of entropy. Does anyone know where this 38 bit figure came from?
- mrsebastian 14y agoYep, from the research paper, page 4: http://bojinov.org/professional/usenixsec2012-rubberhose.pdf http://bojinov.org/professional/usenixsec2012-rubberhose.pdf
- colanderman 14y agoAhh, wow. Thanks. This was totally glossed over in the article copy: We only use 30-character sequences that correspond to an Euler cycle in the graph shown in Figure 2 (i.e. a cycle where every edge appears exactly once). These sequences have the property that every non- repeating bigram over S (such as ‘sd’, ‘dj’, ’fk’) appears exactly once. In order to anticipate the next item (e.g., to show a performance advantage), it is necessary to learn associations among groups of three or more items. This eliminates learning of letter frequencies or common pairs of letters, which reduces conscious recognition of the embedded repeating sequence [5].