16,798 reputation
12785
bio website
location Brooklyn, NY
age 32
visits member for 2 years, 11 months
seen 3 hours ago
Good Morning how are you, I'm dr jimbob
I'm interested in things.
I'm not a real dr,
But I am a real jim bob.

Have a PhD in Experimental High-Energy Physics, but left academia in mid-2010 to program professionally.

Mostly program/script in python, django, and jquery these days doing mostly web apps.

Also have experience programming in C, C++, java, haskell, php, and (bash) shell more in the past.

Linux as primary OS since 1999, ubuntu user since 2005 (Hoary).


1d
comment Which hashing algorithm is ideal for use on the web?
@PTW-105 and SHA-512 will be 2^256 times harder than SHA-256. (That is SHA-512, you have to try for high entropy information would have to try about 13,407,807,929,942,597,099,574,024,998,205,846,127,479,365,820,592,393,377,723,‌​561,443,721,764,030,073,546,976,801,874,298,166,903,427,690,031,858,186,486,050,8‌​53,753,882,811,946,569,946,433,649,006,084,096 different hashes).
1d
comment Which hashing algorithm is ideal for use on the web?
@PTW-105 - The smallest unit of time that makes sense to even think is the Planck time (10^-44 seconds) this is about 1000000000000000000000000000 times smaller than the smallest unit of time we've ever measured. It's only been about ~10^61 Planck time old since the big bang is about ~10^61. Note there are about 3 million billion more SHA-256 hashes than Planck times since the big bang. (So hash ever Planck time since the big bang would have 1 in 3 million billion chance.)
1d
comment Which hashing algorithm is ideal for use on the web?
@PTW-105 All hashes will be brute-forced? That's quite the ridiculous claim. There are 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457‌​,584,007,913,129,639,936 unique 256-bit hashes. Reverse this sha-2 (256 bit -- I was nice even chose the weaker one) f80aca950ca3eabc7ce99d2be088257dec01c9c4f7c841854702acdbb07c76b1. I'll give you $1000 if you or anyone else can do it.
1d
comment Can “cat-ing” a file be a potential security risk?
@IvanKovacevic - echo -e '\x1BZ' works in Mac OS X 10.9 (as well as linux), Terminal 2.4, with my default terminal settings (declared as xterm-256color, don't allow VT100 application).
Apr
18
comment Is it possible to use SSH agent for generic data encryption?
ssh-agent (in SSH1) was trained to automatically decrypt challenge messages presented by a potentially hostile server and send the hashes back over the internet. If it sent the original messages that would be a potential vulnerability. gpg-agent doesn't deal with networking directly; it decrypts/encrypts messages locally only with a key that's presumably only used to connect to SSH.
Apr
17
comment How to sign data with OpenSSL 0.9.8?
While not disagreeing, the 0.9.8 line of OpenSSL was last updated in Feb 2013 (0.9.8y), so some types of major vulnerabilities in OpenSSL were fixed (and 0.9.8 never had features like heartbeats), granted the 0.9.8 line never supported things like the latest version TLS 1.2.
Apr
17
comment How to prevent attacks before HSTS is established for the first time?
@KnightOfNi - And training users may not involve simply "sending an email" or making them take an online quiz. Training entails anything that can change the user's behavior. It could involve say serving http versions of pages that as soon as they select the password field to start typing a big warning pops up saying "THIS IS NOT AN HTTPS PAGE. NEVER TYPE A PASSWORD INTO AN HTTP PAGE. This was not a real attack, but attacks like this exist in the wild. (And then logs whatever username/IP address was used there)." Sort of similar to ismycreditcardstolen.com
Apr
17
comment How to prevent attacks before HSTS is established for the first time?
I'm not saying that training users will be reliable -- some users will find ways to ignore any sensible advice. But I am saying it is a sensible step in addition to others (like HSTS). At the very least it is a CYA practice and at best some rare user actually follows your advice and notices the URL is not colored with https and stops an attack.
Apr
17
comment What's wrong with my own authentication scheme?
@immibis - I brought it up, assuming the username, password hashes, and possibly tokens are stored and checked a database of some sort and potentially a source of injection attack if done poorly.
Apr
16
comment What's wrong with my own authentication scheme?
@Rell3oT - It was not intended to be an exhaustive list, just a quick answer that the vague scheme is already attackable via CSRF. As an aside, listed a few more things that can be done wrong. Session management obviously depends on the application -- being logged into an unimportant account (say reddit as a normal user) doesn't need the same short-lived session requirements that a bank needs. And I did mention the two relevant cookie flags. Granted the number of flaws are innumerable; just gave a few. Others: token guessable, weak passwords allowed, weak pw reset mechanism, etc.
Apr
16
comment What's wrong with my own authentication scheme?
+1 @jimbob gives you a few (and the list is not exhaustive at all) -- Said list was not intended to be exhaustive. Started just describing the obvious CSRF vulnerability in the described part and then felt like adding a few other common things that popped to mind just in regard to authentication (ignoring things like XSS, LFI) as well as user access control, restricting access, secure generation random tokens, weak or reused passwords, don't log passwords in plaintext in server logs, etc
Apr
15
comment Is it possible to use SSH agent for generic data encryption?
@techtonik - I should add there are other agents; e.g., gpg-agent that act similarly to ssh-agent by keeping your passphrase protected encryption keys available for reuse (for a configurable amount of time), so you don't have to keep typing them long passphrases.
Apr
15
comment Is it possible to use SSH agent for generic data encryption?
@techtonik, if you encrypt sensitive data with your private ssh key, you wouldn't want a strong attacker (who can tamper network traffic) to be able to replace the actual sent SSH1 challenge with some sensitive document you encrypted, where ssh happily replies with decrypted document for the tamperer to steal. Would be safer to only leak the hash of the decrypted stream. Also, exposing the full ciphertext using textbook RSA opens it up to several attacks; really should do something like PKCS1v2 before using RSA key. Hashing mitigates some of the more obvious attacks.
Apr
15
comment Is it possible to use SSH agent for generic data encryption?
@techtonik - Updated my answer. To summarize, no, it is not possible to use the private key in ssh-agent for any purpose other than ssh authentication. This is a good thing; otherwise an attacker could extract the private key (without resorting to trying to read the memory of ssh-agent as root).
Apr
14
comment Heartbleed: Why does the client supply the length of the message at all?
@PeterDettman - At that point the standard said just dump the payload and padding -- didn't specify how the payload / padding was differentiated (presumably a header not deigned to mention at that point). Juho first said let's specify the header, (2) and was concerned why these fields are allowed to be so large (concerned about both types) and that if you allow 2^14 - 5= 16379 that requires a uint16 (two byte field).
Apr
14
comment Heartbleed: Why does the client supply the length of the message at all?
@PeterDettman - I added another long section with nuggets seen in the TLS IETF mailing list. It's interesting that many several people noted this potentially opens up side channel attacks. Adding randomized padding seems to be poorly justified based on an analysis of DAE and vague hope to prevent flaws of bad ciphers (meanwhile let's open this side channel).
Apr
13
comment Heartbleed: hackers have already used the vulnerability?
@Clockwork-Muse - Fixed.
Apr
11
comment Ethicality of websites that test other sites for Heartbleed
It is easy to test for heartbleed vulnerability without the risk of getting any valuable data; e.g., you have payload length of 20, but only send 16 bytes (minimum size). Does it fail as it should or does it return 4 extra bytes? Those four bytes of exposed memory will not in anyway be useful to attack the system. However, it does indicate the system is likely vulnerable.
Apr
11
comment How to explain Heartbleed without technical terms?
@MichaelBorgwardt - I tried giving a thorough answer without resorting to just technical jargon or giving silly analogies. I believe some found it helpful. It's not obviously not an "Explain it like I'm a five" or explain it in under a minute, but take the time to explain and related concepts like you are an intelligent adult, even if you aren't a computer/security expert.
Apr
11
comment Does xkcd.com/1353 overstate heartbleed's capability?
@AviD - I think Mr Munroe takes heartbleed very seriously as today's comic also discusses heartbleed in depth (and gives a great summary of it). So I don't see it dripping in sarcasm (besides the obvious comic parts referring to imaginations/paper/clay tablets being safe and the Blade Runner quote).