In computing, entropy is the randomness collected by an operating system or application for use in cryptography or other uses that require random data. This randomness is often collected from hardware sources, either pre-existing ones such as mouse movements or specially provided randomness ...

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Password entropy match for alphanumeric but there are special characters in password

I have a problem cracking some of the fundamentals on passwords' entropies. Namely: I have read this article about a guy cracking DKIM of Google (maybe more noticing that the keys are only 512 bits) ...
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61 views

How to check randomness of a hash?

I have a REST api in which the server allots a unique token each time a user is logged in. Its a hash containing numbers,letters and a one or two special chars. I want to check the entropy of these ...
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1answer
246 views

Where does /dev/random get its entropy?

I read over and over about how /dev/random gets its entropy from "hardware events." What exactly are these hardware events and how can we be sure that it is random enough?
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1answer
190 views

How to keep a reasonable level of entropy in an encrypted file?

Encrypted (or random) data, by nature exhibit a high entropy value and non unencrypted data will exhibit a low entropy value. From an attacker point of view the precense of this high entropy value in ...
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1answer
141 views

Minimum SHA256'd UTF8 encoded passphrase length not stored anywhere

For a passphrase that is UTF8 encoded and then SHA256'd, what is the minimum length to achieve a practically collision free result? The implementation is for a 32 byte cryptocurrency ed25519 seed ...
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0answers
20 views

Evaluating a noise source for a RNG - defining a one-paramter family for RNG [closed]

I am trying to evaluate a noise-source as a means of providing entropy to a random number generator. I am running into trouble when it comes to determining the probability distribution that has the ...
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6answers
817 views

Using passwords made of words

People say don't use passwords in the dictionary but if you use two words isn't it alright? Dictionaries have at least 10,000 entries so just two words will be 100,000,000 possibilities (and that's ...
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1answer
291 views

What multiplier to use when calculating the average time to crack passwords with a given entropy?

Suppose that we have a process that generates passwords with entropy E. I'd like to compute the average time it would take for a brute-force attack to crack an MD5-hashed instance of such a password. ...
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1answer
3k views

Why is /dev/random so slow on Linux? [duplicate]

If it's true you only need about 128 bits of entropy to fuel enough data forever, why is it that /dev/random is so slow? My system has uptime of 214 days! Is it really only gathering .000000001 bits ...
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130 views

Do you need more then 128bit entropy

UUID use 128 bit numbers. Currently it is not feasible to randomly produce two UUIDs that are the same. Does that means 128 bits of entropy is suitable for all cryptographic operations? I would ...
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2answers
59 views

How much entropy should passphrases for encrypting ssh keys have?

When one generates keys using ssh-keygen one gets prompted for a passphrase to encrypt the generated key with. How strong should such a passphrase be, entropywise, to withstand a full-blown ...
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1answer
96 views

How strong is this encryption? [closed]

Given Dictionary containing 1000 three-letter words: dictionary=abc,def,ghi,jkl,mno,pqr... Randomly chosen words from the dictionary: 10-bits-passwords=abc,def,ghi Randomly chosen three words from ...
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1answer
104 views

Does adding an extra, non-entropic keyfile lower security? [duplicate]

Suppose I create two TrueCrypt volumes using keyfiles. The first volume uses a keyfile generated by TrueCrypt, whereas the second one uses the same keyfile in addition to a second, non-entropic ...
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2answers
94 views

How much stronger does a paragraph/sentence based password becomes with random characters added?

I was reading some questions on here regarding the correct horse battery staple method, and the conclusion was that, assuming any words in the list of most common English words, every word adds about ...
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1answer
51 views

A simple question about entropy and random data

Let's say I roll a 6-sided die 100 times and record the results into a 100 character string, for example: //this is obviously an example (and very unlikely) outcome ...
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1answer
34 views

Entropy on payload

How can I guess if a payload is obfuscated or encrypted? in other words can I apply Shannon Entropy algorithm to a binary payload? any advice will be appreciated, thanks in advance
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1answer
167 views

physical access proof smart card for disk encryption [closed]

Current full disk encryption on mobile devices rely on low entropy passwords like PIN numbers or pattern locks. Being able to use a smartcard with such mobile devices is a tempting idea. I know that ...
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7answers
2k views

Are passwords made up from concatenating a few foreign words better than shorter random characters? [duplicate]

Does it make sense to insert a foreign word into a paraphrase to mitigate against brute force? For example: "pussiMeansCatInEskimo" "caballoMeansHorse" "CatIsGatto" "SalopeMeansBitch" ...