bopsbe.blogg.se - What does entropy mean

WHAT DOES ENTROPY MEAN VERIFICATION
WHAT DOES ENTROPY MEAN PASSWORD

nslookup command in Linux with Examples.

Implementation of Diffie-Hellman Algorithm.

Transmission Modes in Computer Networks (Simplex, Half-Duplex and Full-Duplex).

Types of area networks - LAN, MAN and WAN.

Network Devices (Hub, Repeater, Bridge, Switch, Router, Gateways and Brouter).

ISRO CS Syllabus for Scientist/Engineer Exam.

ISRO CS Original Papers and Official Keys.

GATE CS Original Papers and Official Keys.

, so a pretty good password, right? Actually, if your attacker knows you're a cryptography fan, there's no need to assume concatenated names of famous knitters, which makes a guessing attack easier than it might have been. Not in any dictionary anywhere, really long, probably not maximally random but the entropy estimate algorithms would probably rate it highly. Ok, so choose 10 (or 50 or whatever) names from the great cryptographers list, and concatenate them (alternating one backwards, then one forwards, and so on, if you like) to produce a password. Don't use Post-it notes stuck in clever places either.

WHAT DOES ENTROPY MEAN PASSWORD

This leads to writing the long random password down, and to the sort of attack one saw in War Games. For the reasons covered in the prior answers.īut no human (Hans the clever horse might have been able to do better) can remember random stuff very well, and long random stuff still less well. So, IF we assume brute force is an attacker's best choice, a long password, chosen entirely randomly, is a good choice. Regardless of how randomly (ie, high entropy) that single letter was chosen. A password consisting of a single letter is pretty poor since it will fall in, on average, 13 guesses (we assume a 26 character alphabet here, sorry non-English speakers). And it is very correct, very learned, analysis addressing the wrong problem.Ĭonsider that the sole point of a password is to be unguessable (ie, not findable) by an attacker. Much of the math in the prior answers here is quite correct. The practical maximum is how much you can reliably remember and conveniently input into your devices.

Choosing passwords uniformly at random is a good strategy-there's no "arms race" between the attacker and the defender, you can be certain that the strength of your passwords follows from the size of the set you draw them from.

Even the best meters are estimating password strength, and the estimates will often be wrong.

You shouldn't trust password strength meters too much.

The obvious difficulty here is that to estimate the password's entropy you need to think like the attacker-there's a risk that the attacker can outsmart you and find ways to efficiently attack passwords that your model estimates are stronger than they really are. The upper bound for the entropy is $$\leq) + 1 = 44$ bits.

What I strongly suspect this tool to be doing is to analyze the character set used in your password, looking for common words in a dictionary and then making its guess for the entropy (try this by comparing the entropy of potat with potato, the latter being reported at 12 bits and the former at 20). How is entropy calculated and how may my addition of a new character Shortly put: Let $l$ be the actual entropy (in bits), then there are $2^l$ possible different values to be tried. So if you increase the entropy by one, the string is twice as uncertain and thus can take twice as many values which means an attacker has to try twice the amount of passwords. How does entropy actually apply to the length of time it may take forĮntropy denotes the uncertainity in a string 1 and is measured logarithmically in bits. If your entropy is "true" (ie what is reported would actually be the entropy), then there's literally no point in going beyond 256-bit and maybe even 192-bit. Going above 500-bit is very likely to be overkill, even for an actually imperfect source of entropy.

WHAT DOES ENTROPY MEAN VERIFICATION

And even with a super-fast verification function 96-bit should be just out of reach of attackers. After all password usually go through some slow password hashing which increases the work load for attacks significantly. For a password, something around truly 96-bits of entropy is enough.