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Diceware is a method for creating passphrases, passwords, and other cryptographic variables using ordinary dice as a hardware random number generator. For each word in the passphrase, five rolls of the dice are required. The numbers from 1 to 6 that come up in the rolls are assembled as a five-digit number, e.g. 43146. That number is then used to look up a word in a word list. In the English list 43146 corresponds to munch. By generating several words in sequence, a lengthy passphrase can be constructed.
Contents
Lists have been compiled for several languages, including Chinese, Danish, Dutch, English, Esperanto, Finnish, French, German, Italian, Japanese, Maori, Norwegian, Polish, Romanian, Russian, Spanish, Swedish and Turkish. A Diceware word list is any list of
The level of unpredictability of a Diceware passphrase can be easily calculated: each word adds 12.9 bits of entropy to the passphrase (that is,
This level of unpredictability assumes that a potential attacker knows that Diceware has been used to generate the passphrase, knows the particular word list used, and knows exactly how many words make up the passphrase. If the attacker has less information, the entropy can be greater than 12.9 bits per word.
The above calculations of the Diceware algorithm's entropy assume that, as recommended by Diceware's author, each word is separated by a space. If, instead, words are simply concatenated, the calculated entropy is slightly reduced due to redundancy; for example, the three-word Diceware phrases "in put clammy" and "input clam my" become identical if the spaces are removed.
EFF wordlists
The Electronic Frontier Foundation published three alternative English diceware word lists in 2016, further emphasizing ease-of-memorization with a bias against obscure, abstract or otherwise problematic words; one tradeoff is that typical EFF-style passphrases require typing a larger number of characters.
Snippet
The original diceware word list consists of a line for each of the 7,776 possible five-die combinations. One excerpt:
...43136 mulct43141 mule43142 mull43143 multi43144 mum43145 mummy43146 munch43151 mung...Examples
Diceware wordlist passphrase examples:
EFF wordlist passphrase examples:
Swedish-language example: