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Questions tagged [timing-attack]

32 questions
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Are there other C standard library functions like memcmp that have timing side-channel risk?

I found that memcmp() will return false earlier if the first byte is different in both strings, and I thought it has a timing attack risk. However, when I tried to find out if there were other functions that had side-channel risks like memcmp, I…
zhxf7481
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Fixing a timing attack

I use this code to login a user. The password is encrypted with bcrypt and the SALT_ROUNDS is the same for every user const user = await User.findOne({email: args.email}); if (!user || !await user.comparePassword(args.password)) throw new…
riggedCoinflip
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Is checking the existence of an objects key considered timing safe?

So, I'm authing a pretty short list of users for a mostly private server, and the login data for these users in stored in an object. The object is structured like {"username":"hash"}. I'd like to know if using something like if(users[username)…
Werlious
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Function to count time with precision less than a millisecond

I have a function here that can make program count, wait etc with least count of 1 millisecond. But i was wondering if i can do same will lower precision. I have read other answers but they are mostly about changing to linux or sleep is guesstimate…
monster
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Reducing an integer to 1 if it is not equal to 0

I'm trying to solve a timing leak by removing an if statement in my code but because of c++'s interpretation of integer inputs in if statements I am stuck. Note that I assume the compiler does create a conditional branch, which results in timing…
Kasper
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How can I understand whether my C code is constant time or not?

I have a code for polynomial multiplication and it is written in C. I heard that whether a particular instruction is "constant time" can vary by architecture and by processor model and there isn't any official documentation for this behavior. How…
esra
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nodejs: timing attack on "=="

Recently I came past this write up of a CTF on hackerone. In this writeup part of completing the challenge was to perform a timing attack. It spiked my interest and I wanted to create a webite that would be prone to a timing attack. To do this I…
Mr Krisey
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Cannot detect any meaningful timing difference in PHP (constant timing attack)

There's quite a few articles around PHP stating that constant timing attacks are possible when doing direct string comparisons. I've written some sample code to try and determine the order of magnitude difference but it's showing that it's not…
Adrian
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Split token for PHP login - timing attack

I am creating a PHP login system. User will receive email with a onetime link to the website where the one-time link is gonna be checked and token provided as a cookie/session. My question is how to split the token and/or onetime link to prevent…
stefan999
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PHP constant-time realpath()?

I'm looking for a constant-time implementation of realpath() , does one exist? I'm in a situation where a malicious actor may control the argument for realpath(), and could theoretically use a timing attack to deduce if realpath() pointed to a real…
hanshenrik
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Force PHP to run all if conditions

I am building an application that is sensitive to timing attacks. I was thinking of instead of making an "if tree" where you nest if statement, just run all of the if statements, and then check all of the conditions at the end, like so: if…
AnnoyinC
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Is the time leakage by comparing the hashes of two strings vulnerable?

It is obvious that if we compare two strings it is vulnerable to the time attack. I'm now wondering whether the time leakage is still a vulnerability if the comparison is done on the hash of those two strings? Isn't it vulnerable to any other kind…
HmT
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How could HMAC comparison ever not be constant-time in Python?

Python has a method specifically for comparing HMAC to prevent timing attacks: https://docs.python.org/3.7/library/hmac.html#hmac.compare_digest And I read about timing attacks here:…
davidtgq
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Implementing a side channel timing attack

I'm working on a project implementing a side channel timing attack in C on HMAC. I've done so by computing the hex encoded tag and brute forcing byte-by-byte by taking advantage of strcmp's timing optimization. So for every digit in my test tag, I…
justan0therlurker
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How to have precise time in python for timing attacks?

I'd like to know why python gives me two different times when I re-order the two nested for loops. The difference is that significant that causes inaccurate results. This one almost gives me the result I expect to see: for i in range(20000): …
D J
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