Will all 24 words of a seed-phrase be unique by specification? Or is it possible for a word to occupy two positions (ie the word "tool" is #8 AND #20 in a valid, securely generated seed)
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Does BIP39 mnemonic construction avoid repeating words?
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asked Sep 24 '17 at 0:20
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2 Answers
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There is nothing stopping a word to be repeated more than once. In a 24 word mnemonic, with 2048 possible words in the dictionary (BIP 39), there is a probability of at least one duplicate around 12.7% of the time (variation of the birthday paradox).
answered Sep 24 '17 at 2:22
MeshCollider
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No, the BIP39 construction does not avoid repeating words.
It is possible for a word to show up multiple times, but since there are 2048 words it is fairly unlikely for repeats to show up in randomly generated keys.
answered Sep 24 '17 at 2:16
G. Maxwell
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Does BIP39 mnemonic construction avoid repeating words?
up vote
14
down vote
Will all 24 words of a seed-phrase be unique by specification? Or is it possible for a word to occupy two positions (ie the word "tool" is #8 AND #20 in a valid, securely generated seed)
asked Sep 24 '17 at 0:20
pinhead
3,5222 gold badges16 silver badges29 bronze badges
3,5222 gold badges16 silver badges29 bronze badges
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9
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There is nothing stopping a word to be repeated more than once. In a 24 word mnemonic, with 2048 possible words in the dictionary (BIP 39), there is a probability of at least one duplicate around 12.7% of the time (variation of the birthday paradox).
answered Sep 24 '17 at 2:22
MeshCollider
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9,1603 gold badges19 silver badges43 bronze badges
Preventing duplicate words will in fact restrict the entropy of the seed phrase. - pim Oct 23 '17 at 14:34
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