How many bits of entropy is your bitcoin wallet password?

[Straux]

Hey guys, I have been thinking about my password/passwords for all the different accounts i use (bitcointalk, steam, Skype, Facebook, Google, etc), and ive realised that my password certainly isn't very strong. The only password that I can proudly say is strong is my bitcoin wallet password, which had 322 bits of entropy.

So how about you guys? Are your passwords strong? How strong?

[SFR10]

That's really hell of a password entropy you got there (a wild guess, is it's something between 50 to 70 characters and numbers long, right?). I'm at 98.4 at the moment, perhaps I should be changing it to even more complex one but might have difficulty remembering it though so might think twice for now. Mine is within the strong range and yours within very strong range.

[Erkallys]

Maybe this will be considered as a total newbie question, but I don't care : what is exactly "bits of entropy" ? Is it the numbers of caracters, letters, and numbers, with all unique coefficeient, or something else ?

[vlom]

you don't have to know. send my you password and i will tell you its bits of entropy 

yeah: i don't know neither what this is.

[shorena]

Maybe this will be considered as a total newbie question, but I don't care : what is exactly "bits of entropy" ? Is it the numbers of caracters, letters, and numbers, with all unique coefficeient, or something else ?

Entropy is a measurement how "unexpected" a certain information is. E.g. the information "the vulcano did not break out today" has very low entropy, because its a common event. The information "the vulcano did break out today" on the other hand is a rare event and as such has a high entropy. Its measured in bits, see more here[1]

For passwords its simple, you just calculate the number of possible outcomes and take the result log2. E.g. if you have a 16 symbol password made up from 62 different (e.g. [a-zA-Z0-9]) symbols you calculate:

log₂((2*26+10)¹⁶) = 95 bit

If your caluclator does not support log₂ (most dont) you can do log(62¹⁶)/log(2) instead to get the same result.

If you use words or other things as symbols you have to replace the 62 by the number of words or other things you selected them from. If you e.g. randomly selected the names of two friends and you have 100 people you would call such the entropy would be log₂(100²) = 13 bit

[1] https://en.wikipedia.org/wiki/Entropy_(information_theory)

[Erkallys]

Maybe this will be considered as a total newbie question, but I don't care : what is exactly "bits of entropy" ? Is it the numbers of caracters, letters, and numbers, with all unique coefficeient, or something else ?

Entropy is a measurement how "unexpected" a certain information is. E.g. the information "the vulcano did not break out today" has very low entropy, because its a common event. The information "the vulcano did break out today" on the other hand is a rare event and as such has a high entropy. Its measured in bits, see more here[1]

For passwords its simple, you just calculate the number of possible outcomes and take the result log2. E.g. if you have a 16 symbol password made up from 62 different (e.g. [a-zA-Z0-9]) symbols you calculate:

log₂((2*26+10)¹⁶) = 95 bit

If your caluclator does not support log₂ (most dont) you can do log(62¹⁶)/log(2) instead to get the same result.

If you use words or other things as symbols you have to replace the 62 by the number of words or other things you selected them from. If you e.g. randomly selected the names of two friends and you have 100 people you would call such the entropy would be log₂(100²) = 13 bit

[1] https://en.wikipedia.org/wiki/Entropy_(information_theory)

Thank you for answering my question. However, for a reason that I still ignore, I get a different result depending on where I write the formula .

[shorena]

Maybe this will be considered as a total newbie question, but I don't care : what is exactly "bits of entropy" ? Is it the numbers of caracters, letters, and numbers, with all unique coefficeient, or something else ?

Entropy is a measurement how "unexpected" a certain information is. E.g. the information "the vulcano did not break out today" has very low entropy, because its a common event. The information "the vulcano did break out today" on the other hand is a rare event and as such has a high entropy. Its measured in bits, see more here[1]

For passwords its simple, you just calculate the number of possible outcomes and take the result log2. E.g. if you have a 16 symbol password made up from 62 different (e.g. [a-zA-Z0-9]) symbols you calculate:

log₂((2*26+10)¹⁶) = 95 bit

If your caluclator does not support log₂ (most dont) you can do log(62¹⁶)/log(2) instead to get the same result.

If you use words or other things as symbols you have to replace the 62 by the number of words or other things you selected them from. If you e.g. randomly selected the names of two friends and you have 100 people you would call such the entropy would be log₂(100²) = 13 bit

[1] https://en.wikipedia.org/wiki/Entropy_(information_theory)

Thank you for answering my question. However, for a reason that I still ignore, I get a different result depending on where I write the formula .

Try wolframalpha -> http://www.wolframalpha.com/input/?i=log2%2862%5E16%29

[Straux]

That's really hell of a password entropy you got there (a wild guess, is it's something between 50 to 70 characters and numbers long, right?). I'm at 98.4 at the moment, perhaps I should be changing it to even more complex one but might have difficulty remembering it though so might think twice for now. Mine is within the strong range and yours within very strong range.

It honestly isn't that hard to remember. It's a 60 letter mathematical phrase that's commonly known that I put punctuation in. It's basically 5 words.

Something like:

The Square Root Of A Multiplied By The Square Root Of B Is Equal To The Square Root Of C.

 ^
  |
  |
Obviously not that, though.

[shorena]

That's really hell of a password entropy you got there (a wild guess, is it's something between 50 to 70 characters and numbers long, right?). I'm at 98.4 at the moment, perhaps I should be changing it to even more complex one but might have difficulty remembering it though so might think twice for now. Mine is within the strong range and yours within very strong range.

It honestly isn't that hard to remember. It's a 60 letter mathematical phrase that's commonly known that I put punctuation in. It's basically 5 words.

Something like:

The Square Root Of A Multiplied By The Square Root Of B Is Equal To The Square Root Of C.

 ^
  |
  |
Obviously not that, though.

So your entropy value is probably wrong, because there are not that many mathematical phrases to choose from. Its like a poem, you cant apply the full entropy for each word, because you did not randomly select the words. They are not equally likely. If you have a higher likelyhood for a given word to appear its entropy is lower.