Polynomial

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Pentester, ex-developer, security researcher, reverse engineer, electronics tinkerer, internet activist, zombie eradicator, promulgator of useless facts, shrubbery inspector, bacon aficionado, devourer of donuts.

Strengths: Security, Crypto, Win32 API, C#, .NET, PHP, x86 assembly

All answers and comments are encrypted with ROT256-ECB.

Opinions are my own. Advice provided with no warranty.

	32,582 reputation	bio	website	en.wikipedia.org/wiki/…	visits	member for	1 year, 7 months
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Mar 11	comment	What statistics can be used to identify pseudorandom data? I'm not as much looking to detect good randomness, as I am looking to detect a lack of non-randomness.
Mar 11	comment	What statistics can be used to identify pseudorandom data? @CodesInChaos x_i is bytes - sorry, the subscript and lowercase is rather confusing. I wanted to use the proper math markup but we don't have it here. It's an implementation taken from a proper stats library, so it is indeed correct.
Mar 11	comment	What statistics can be used to identify pseudorandom data? @F.Hauri I'm only trying to distinguish non-random-looking data from random-looking data, so looking for the average value of the 0th bit across all bytes vs. the average value of the 1st bit across all bytes vs. ... vs. the average value of the 7th bit across all bytes gives me a decent indicator of non-random data (e.g. the 0th byte will have a mean of 0 for standard ASCII).
Mar 10	comment	What should someone learn to get into IT Security? Please don't take our closing of this question as a reason to not get into security, though! It's a great field to get into, and is rapidly growing as a business. Join us in the DMZ for a chat some time if you'd like more informal advice.
Mar 8	comment	What are the disadvantages of Tor? @asadz No, if the server end was compromised it does not mean that the client end would be too. If the client end is compromised, then you've got bigger problems, and the compromise was likely nothing to do with using Tor or a VPN.
Mar 8	comment	Is update@em.facebookmail.com legitimate? "Its most certain that infact an spam relay / server was used to sent this email" - I disagree. It could simply be a legit email from Facebook, with a broken template or data glitch causing the Spanish text in the link. After all, Facebook's email templates and features are written by people, and people make mistakes.
Mar 8	comment	What are the disadvantages of Tor? I agree with @CodesInChaos here. The point is that the endpoint of the Tor network is essentially untrusted when using exit nodes, but placed in a privileged position (potential MitM), so SSH / VPN protocols provide end-to-end security that can protect you against attack vectors from that node.
Mar 8	comment	Is update@em.facebookmail.com legitimate? @D3C4FF The domain was registered by Facebook through an affiliate brand protection company. Makes some sense that it'd redirect.
Mar 8	comment	How risky is it not to install ssl? @asadz I've yet to see a major breach from a free certificate authority, but there have been several on major certificate authorities. If you're really worried about free certs, go for a cheap cert from a reseller. You can get them for as little as $15/yr.
Mar 5	comment	Tools helps: First time cracking passwords I'd have linked the quote to this‌. (warning: audio)
Mar 2	comment	Necessary education for InfoSec? Welcome to StackExchange. Unfortunately, your question is highly subjective and is difficult to answer as-is. It also falls under the "too localised" rule, since it's unlikely to apply to anyone else. Please see the FAQ for more details.
Feb 28	comment	Recovering encrypted SD card after Android Factory Reset Nope. You're pretty much screwed unless you kept a backup of your phone's settings, and even then it might not have backed up the storage key.
Feb 27	comment	Are private keys generated by different software packages compatible? @Frank There are other tools for things like executable signing that use alternative formats.
Feb 27	comment	How high is the entropy of this salt-generating code? (No code-reading actually necessary) The answers here are good, but I'd like to just make the solution 100% clear - you don't need a strong random number generator, you just need to generate a unique value for a salt. A 32-bit integer that increments per-user, e.g. an auto-increment ID, is completely valid as a salt.
Feb 27	comment	How to mitigate SIP Reflection Attacks? @asadz If I understand the attack properly, it's not a DoS really. It's a password-guessing attack with such ferocity that it ends up causing a DoS condition.
Feb 27	comment	How to mitigate SIP Reflection Attacks? @mgjk You could set up a Python script and pipe tcpdump into it for realtime processing, using a filter so that you only have to process SIP registration requests with the script. From there you could identify high-volume requests and automatically maintain `iptables` rules based on that. Essentially your own version of fail2ban for your specific case.
Feb 27	comment	How to mitigate SIP Reflection Attacks? @asadz Nope, there's no way for them to tell. Even if they send a packet whose source IP address is spoofed to that of a whitelisted address, they won't receive the response because the network will respond to the spoofed IP. As such, there's no way to enumerate the whitelist.
Feb 27	comment	How to predict C rand()? As I said, there's no such thing as C's `rand()`. C is a language, and `rand()` is a function provided by a library for that language. The libraries that are used are entirely dependant on the compiler suite you're using, because the RNG that `rand()` is based on is not mandated by the spec. You'll need to specify which compiler and libraries you're using.
Feb 27	comment	How to predict C rand()? More links that cover this: Not so random numbers - take 2, Pwning random number generators, State recovery attacks on pseudorandom generators, Predicting values from an LCG
Feb 27	comment	How to predict C rand()? Note that "C rand()" isn't a defined thing as part of the spec. It's entirely dependant on which compiler / libs you're using.