4 ms·

No, you are wrong. The number of bits of entropy in "horsestaple..." is estimated by assuming the words where chosen at random from the 2^11=2048 most common wo

No, you are wrong. The number of bits of entropy in "horsestaple..." is estimated by assuming the words where chosen at random from the 2^11=2048 most common words. 4*11=44 bits in total. In practice it is even better since a hacker would also try different kinds of passwords! So no, you do not need substitute characters.

hvidgaard 10y ago
Yes, I was wrong about the entropy when writing that. But I still don't think that passphrases are as godsend as the comic make it seem. Can we really assume 2048 common words? The 100 most commonly used, make up 50% of written words. A common sentence like "I drove to the mall yesterday" is not a good passphrase, but I'm certain that people who use "rocket" as a password would do something similar.
- Symbiote 10y ago
  The intention is that the random words are selected from a list of 2000 unique, common words. Choosing a sentence is a different strategy, which is less secure. $ wget -O ⅓Mwords http://norvig.com/ngrams/count_1w.txt $ for i in `seq 10`; awk '/^[a-z]{3,}/ { print $1 }' ⅓Mwords | head -n 2000 | shuf -n 5 | tr '\n' ' ' && echo videos possible disease maintenance chair teen documents than without son research interface library largest drive location ball beauty coming files files middle fri meet air guarantee samsung click super inn legal previous rent resort use reply thought better fresh phentermine bad command once vehicle australian fun random professor course sponsored
  - hvidgaard 10y ago
    A random 5 words is hardly simple or easy to remember. The entire selling point of passphrases is exactly that. It's a hard problem that is IMO best solved with hardware secure keeping of secrets and a rate limited pincode.
    - croon 10y ago
      You're not supposed to remember all your passwords. You will need to remember at least one master password and maybe a couple more. But you can't suggest that remembering 5 random words is harder than 20 random characters? The goal is "simple" if possible, but "simpler" is still a lot better than "practically impossible".
      - hvidgaard 10y ago
        I'm not suggesting that 20 random characters is easier to remember, but for average Joe, it might as well be the same. Not only do they have to remember the words, the sequence, and how to spell them. Unfortunately we cannot expect this from users in general - the worst offenders write down a password like "rocket", so there is no hope that they'll try to remember a sequence of random words. We shouldn't have remember passwords at all IMO. It's creating entropy by remembering things, but the human brain is inheritly bad at remembering exact things. Things like a yubikey is a better idea, plug it in, enter your pincode, and use a key pair to authentication. All the user have to do is keep track of the physical thing and the pincode.
    - tripzilch 10y ago
      > A random 5 words is hardly simple or easy to remember You use well-known the mnemonic trick demonstrated in the last panel of the comic.
- leshow 10y ago
  the idea is you use a mnemonic generator to pick the words. The fact that "100 most commonly used, make up 50% of written words" (a dubious statistic, source?) is irrelevant. Here's a mnemonic generator I wrote in Rust https://github.com/leshow/rust_mnemonic https://github.com/leshow/rust_mnemonic for example
  - hvidgaard 10y ago
    > The fact that "100 most commonly used, make up 50% of written words" (a dubious statistic, source?) is irrelevant. See https://en.wikipedia.org/wiki/Most_common_words_in_English https://en.wikipedia.org/wiki/Most_common_words_in_English for a claim. It is what teachers use as a guideline. It's the first 100 words they teach children to write. > the idea is you use a mnemonic generator to pick the words. I know you are supposed to use a generator to pick the words, that is how BIP39 for bitcoin works. But average Joe is not going to do that. He will select "I went to highschool in 1992". Authentication is a hard problem, and unless you force a reasonable scheme, it will be weak.
- marcosdumay 10y ago
  Even those 44 bits are too little nowadays. Passphrases are not a godsend, but something good to use when the correct technology - a password manager - is not available. A notable use case is choosing a master password for your password manager. And you'll want a longer phrase.

hvidgaard 10y ago

Yes, I was wrong about the entropy when writing that. But I still don't think that passphrases are as godsend as the comic make it seem. Can we really assume 2048 common words? The 100 most commonly used, make up 50% of written words. A common sentence like "I drove to the mall yesterday" is not a good passphrase, but I'm certain that people who use "rocket" as a password would do something similar.

Symbiote 10y ago
The intention is that the random words are selected from a list of 2000 unique, common words. Choosing a sentence is a different strategy, which is less secure. $ wget -O ⅓Mwords http://norvig.com/ngrams/count_1w.txt $ for i in `seq 10`; awk '/^[a-z]{3,}/ { print $1 }' ⅓Mwords | head -n 2000 | shuf -n 5 | tr '\n' ' ' && echo videos possible disease maintenance chair teen documents than without son research interface library largest drive location ball beauty coming files files middle fri meet air guarantee samsung click super inn legal previous rent resort use reply thought better fresh phentermine bad command once vehicle australian fun random professor course sponsored
- hvidgaard 10y ago
  A random 5 words is hardly simple or easy to remember. The entire selling point of passphrases is exactly that. It's a hard problem that is IMO best solved with hardware secure keeping of secrets and a rate limited pincode.
  - croon 10y ago
    You're not supposed to remember all your passwords. You will need to remember at least one master password and maybe a couple more. But you can't suggest that remembering 5 random words is harder than 20 random characters? The goal is "simple" if possible, but "simpler" is still a lot better than "practically impossible".
    - hvidgaard 10y ago
      I'm not suggesting that 20 random characters is easier to remember, but for average Joe, it might as well be the same. Not only do they have to remember the words, the sequence, and how to spell them. Unfortunately we cannot expect this from users in general - the worst offenders write down a password like "rocket", so there is no hope that they'll try to remember a sequence of random words. We shouldn't have remember passwords at all IMO. It's creating entropy by remembering things, but the human brain is inheritly bad at remembering exact things. Things like a yubikey is a better idea, plug it in, enter your pincode, and use a key pair to authentication. All the user have to do is keep track of the physical thing and the pincode.
  - tripzilch 10y ago
    > A random 5 words is hardly simple or easy to remember You use well-known the mnemonic trick demonstrated in the last panel of the comic.
leshow 10y ago
the idea is you use a mnemonic generator to pick the words. The fact that "100 most commonly used, make up 50% of written words" (a dubious statistic, source?) is irrelevant. Here's a mnemonic generator I wrote in Rust https://github.com/leshow/rust_mnemonic https://github.com/leshow/rust_mnemonic for example
- hvidgaard 10y ago
  > The fact that "100 most commonly used, make up 50% of written words" (a dubious statistic, source?) is irrelevant. See https://en.wikipedia.org/wiki/Most_common_words_in_English https://en.wikipedia.org/wiki/Most_common_words_in_English for a claim. It is what teachers use as a guideline. It's the first 100 words they teach children to write. > the idea is you use a mnemonic generator to pick the words. I know you are supposed to use a generator to pick the words, that is how BIP39 for bitcoin works. But average Joe is not going to do that. He will select "I went to highschool in 1992". Authentication is a hard problem, and unless you force a reasonable scheme, it will be weak.
marcosdumay 10y ago
Even those 44 bits are too little nowadays. Passphrases are not a godsend, but something good to use when the correct technology - a password manager - is not available. A notable use case is choosing a master password for your password manager. And you'll want a longer phrase.