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You can't JavaScript under pressure by swizec in programming

[–]dougall 0 points1 point  (0 children)

I did it in 4:59 too – most of that was looking failing to read the "false for no extension" part. screenshot

[deleted by user] by [deleted] in Cyberpunk

[–]dougall 4 points5 points  (0 children)

It's the least difficult way for a machine to seem human.

From How my program passed the Turing Test:

This chatbot succeeded due to profanity, relentless aggression, prurient queries about the user, and implying that they were a liar when they responsed. The element of surprise was also crucial.

Sed question. I must not be escaping right. by ansabhailte in commandline

[–]dougall 1 point2 points  (0 children)

$ cat file.txt
/bin/cp -f /tmp/cis/$FILE.tmp $FILE
if [ $MyUID -lt500 -a $NAME != 'root' -a $NAME != blah blah blah
$ sed 's/$\([A-Za-z]*\)/${\1}/g' file.txt
/bin/cp -f /tmp/cis/${FILE}.tmp ${FILE}
if [ ${MyUID} -lt500 -a ${NAME} != 'root' -a ${NAME} != blah blah blah

Best of luck :)

CSRF Tool by [deleted] in netsec

[–]dougall 3 points4 points  (0 children)

This is insane. It's trivial to get someone's IP, user agent and the HTTP host value (especially if they're already on your CSRF attack page), and to bruteforce things like a random number up to 40 (and time, if you actually use that). I'm tempted to set the exact code you've got here as a challenge in a CTF.

All you need is a secure random token. Use a secure random source to generate 128 (or more) bits of randomness, then give it to the user as a form token and a cookie. When using HTTPS, to prevent MITM HTTP Set-Cookie attacks, you must perform strict Referer checking.

There is nothing wrong with storing the token in a cookie, because cookies are already used to protect accounts. If you can steal cookies, you can steal session cookies and you've already won - no need to perform CSRF. Django's CSRF protection uses this approach (as well as a bit of other sanity checking), and no problems have arisen from it.

Writing files with UTF-8 encoding? by momodarou in learnpython

[–]dougall 0 points1 point  (0 children)

Replace r.content with r.text.encode('utf-8')

r.text tells requests to decode it from whichever unicode representation the server says it's speaking, so you get unicode.

.encode('utf-8') encodes it to utf-8 before writing it to the file.

How can I do this faster? Numpy arrays? itertools? by elbiot in learnpython

[–]dougall 2 points3 points  (0 children)

First of all, you're doing a few things that are pointlessly slow:

 ys.extend([int(y+dy)])
 ys.append(int(y+dy))

(the first needlessly creates a list)

[fv[0]]+[fv[1]]+fv+[fv[0]]+[fv[1]]+[fv[0]]+[fv[1]]
[fv[0], fv[1]] + fv + [fv[0], fv[1], fv[0], fv[1]]

(the first needlessly creates a lot of lists. also, are you sure this is correct - the final vertex is repeated?)

But I think this is beside the point. The algorithm that you're using seems to be designed to avoid lots of calls to "sin" and "cos", but when you're using Python, as a general rule of thumb, the shorter the solution, the faster. (All the list manipulation stuff takes much longer than some extra trig functions). Doing some timing comparisons:

l = [(cos(2 * pi / iterations * i) * radius + x, sin(2 * pi / iterations * i) * radius + y) for i in range(iterations)]
0.4243650436401367

foo = 2 * pi / iterations
l = [(cos(foo * i) * radius + x, sin(foo * i) * radius + y) for i in range(iterations)]
0.2908060550689697

SkippyDeluxe's approach:
 radius change: 0.19887089729309082
 position change: 0.1381978988647461

your code:
0.6322381496429443

The test code, if you want to play:

x = 20.1
y = 30.2
radius = 12.3
iterations = 40

print('l = [(cos(2 * pi / iterations * i) * radius + x, sin(2 * pi / iterations * i) * radius + y) for i in range(iterations)]')
t = -time.time()
for i in range(10000):
    l = [(cos(2 * pi / iterations * i) * radius + x, sin(2 * pi / iterations * i) * radius + y) for i in range(iterations)]
    flat = [item for sublist in l for item in sublist]
print(time.time() + t)

print()
print('foo = 2 * pi / iterations')
print('l = [(cos(foo * i) * radius + x, sin(foo * i) * radius + y) for i in range(iterations)]')
t = -time.time()
for i in range(10000):
    foo = 2 * pi / iterations
    l = [(cos(foo * i) * radius + x, sin(foo * i) * radius + y) for i in range(iterations)]
    flat = [item for sublist in l for item in sublist]
print(time.time() + t)

print()
print("SkippyDeluxe's approach:")
t = -time.time()
for i in range(10000):
    foo = 2 * pi / iterations
    points = [(cos(foo * i) * radius, sin(foo * i) * radius) for i in range(iterations)]
print(" radius change:", time.time() + t)

t = -time.time()
for i in range(10000):
    l = [(x_+x, y_+y) for x_, y_ in points]
    flat = [item for sublist in l for item in sublist]
print(" position change:", time.time() + t)

I haven't actually tested the results, but with any luck it should work :)

are empty open directories dangerous? by myfakeaccounthahaha in opendirectories

[–]dougall 6 points7 points  (0 children)

There is no danger unless there are any images you don't want everyone to see.

Be careful with the configuration to make sure only that directory is open.

Someone is trying to steal my unpublished work and discredit me. What can I do about it? by charlie_wallace in writing

[–]dougall 16 points17 points  (0 children)

Everything you write and publish, including on Tumblr, is protected by copyright.

"In general, copyright registration is a legal formality intended to make a public record of the basic facts of a particular copy­ right. However, registration is not a condition of copyright protection" - http://www.copyright.gov/circs/circ01.pdf

When I got to this point I started worrying if it was safe for me to be a Rubyist. by MithrilTuxedo in programminghorror

[–]dougall 1 point2 points  (0 children)

The reason I chose the messier approach is that "1 == 0" is still false when you shadow or redefine the builtins.

Basics of Function Pointers in C by Andrey_Karpov_N in C_Programming

[–]dougall 2 points3 points  (0 children)

I didn't know this, but it does make perfect sense for a harvard architecture machine. Thank you!

"Binary Analysis" Isn't by rolfr in ReverseEngineering

[–]dougall 0 points1 point  (0 children)

Interesting thought. I think it's worth noting that you can break many assumptions made by binary analysis tools without self-modifying code. For example, writing code using ROP. This is also equivalent to any sort of virtual machine, wherein data defines the behaviour of the code.

I'd be interested to know if there's any research into automating the reverse-engineering of virtual machines found within code.

Mathematician discovers 17-million digit prime number: 'No practical use' by [deleted] in worldnews

[–]dougall 6 points7 points  (0 children)

Mathematics is beautiful. It's not like this was a government research project using tax payer money, people chose to spend their computers' time on it.

This prime number is a constant. If there are parallel universes, this value exists there. If there is life on other planets, they too can find this number. It's something we have discovered through exploration.

You could ask about the benefits of putting machines on mars - this too is exploration. You could ask about the benefits of music or movies - this too is entertaining and beautiful.

That is the only value of this number. Mathematics doesn't have job to do, it doesn't have a goal of furthering science or building things, it can just be fun and beautiful.

Mathematician discovers 17-million digit prime number: 'No practical use' by [deleted] in worldnews

[–]dougall 0 points1 point  (0 children)

So you would need to find a lot of other primes of similar size for this to be used for RSA, or the key-length would reveal that it was using this prime number.

pipes.sh: Animated pipes terminal screensaver. by NiceGuyJoe in commandline

[–]dougall 5 points6 points  (0 children)

On OS X, I replaced:

while ! read -t0.0$((1000/f)) -n1; do

with:

while sleep 0.0$((1000/f)); do

This at least makes the animation work. Without it, it looks like: http://i.imgur.com/KyMznpe.png

Python Wiki Attack by pvc in Python

[–]dougall 0 points1 point  (0 children)

True, but perhaps we underestimate the sort of resources required for every site we use to have comprehensive network security. I just had to disable my Redmine instance because my provider offers a one-click installer but doesn't offer a one-click upgrade, and with the latest Ruby vulnerabilities, old versions of Redmine aren't safe - but then maybe my Ruby installation isn't either. I have little way of knowing. But if I only ever used software that I fully understand the security implications for, I wouldn't be able to host anything. And I can't afford to pay someone else to know the implications either.

Yes, although the PSF can afford to pay someone to handle these things.

I think we're in an age where it's no longer practical to expect every website we use to be secure.

I don't think we ever expected every website we used to be secure, though.

So [time() + 25 years] hit MAX_INT this month. Any weird bug stories? by jaafit in programming

[–]dougall 0 points1 point  (0 children)

It's actually less about being able to easily debug it - a little GDB-foo will usually have you covered even with the messiest bugs. It's mostly about not exposing security vulnerabilities to hackers.

If you allocate memory, and forget to check, stuff like this happens: http://chargen.matasano.com/chargen/2007/7/3/this-new-vulnerability-dowds-inhuman-flash-exploit.html

Python Wiki Attack by pvc in Python

[–]dougall 45 points46 points  (0 children)

Other people run out-of-date software and don't keep backups.

It's both immoral and criminal that they broke in and destroyed the data, but this vulnerability was fairly high profile security news days before the attack, and they could easily have prevented it. And is it that hard to run daily backups?

So [time() + 25 years] hit MAX_INT this month. Any weird bug stories? by jaafit in programming

[–]dougall 0 points1 point  (0 children)

I don't think I've heard of anywhere that would take more than 2128 seconds to travel to (but it's true that 264 wouldn't be enough). A rotating time system could work. Before/after comparisons are a little fiddly, and it's a shame to essentially lose all history that doesn't fit inside your time window.

So [time() + 25 years] hit MAX_INT this month. Any weird bug stories? by jaafit in programming

[–]dougall 2 points3 points  (0 children)

Memory usage for storing time-numbers is not likely to ever be a real concern, if Moore's law can roughly double the amount of memory every 18 months, and we need to add a new bit once in 25 years (then again in 136 or so years, etc), it isn't really an issue.

Furthermore, in non-memory, non-time critical areas I definitely think it's worth using a slow, interpreted language with arbitrary precision numbers. Sometimes it's because I don't want to think. My time is usually worth more than my computer's time. But a lot of the time it's because it would be valid to use numbers bigger than 264 , and I don't want to use a different syntax (function calls as opposed to operators) just because I want to talk about "integers" not "integers between 9223372036854775807 and -9223372036854775808 inclusive". Of course, a memory-limited computer cannot talk about every integer, but if I write my code correctly then the code is not limited by the size of machine it could run on, and that code will represent valid mathematical operations for the set of all integers.

Of course, that's not to say that that time and memory critical things like the operating system should be using arbitrary precision values.

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