No, CRC would make a terribly bad content identifier.
Of course, it would. Precisely for the reasons I outlined.
First of all, a usual 32-bit CRC is too short: by birthday paradox
I didn't say anything about 32 bits. You can make it any power of 2. It's effectively just a remainder of dividing by an irreducible polynomial in an extension field of F_2. I wasn't suggesting using it.
I was saying that Linus was being flippant by ignoring a problem with a trivial solution and he doubled down by claiming that the only functionality he was looking for was something which needs less than cryptographic-level randomness. But what he ended up saying was tantamount to saying that the functionality he needed might just as well be achieved with CRC (no, not 32... probably 128, but certainly with 256). He was basically saying he needed a large enough pointer to be unique across all data which we can expect to be conceivably computable in the next X years. And he was completely ignoring the fact that this created a vector of attack on searchability.
Btw, birthday "paradox" collision is not enough to hinder searchability, so they are not a concern.
a longer CRC is not fast.
It scales linearly with the size of the signature. It's just polynomial division. And dividing by a polynomial of a degree that's twice as high would take exactly twice as long. So (a properly implemented) CRC-128 should take 4 time as long as CRC-32.
You don't have to believe me on the following, but (1) I have a math PhD, (2) I do write a lot of code and (3) I've implemented functions based on these algorithms. So just take it easy with the hyperbole.
Don't confuse possible and feasible. It's not proven that the discrete log problem has no linear-time solution. But there is no known linear time solution, so we rely on this problem remaining unsolved in order to trust our encryption.
It's a little harder to say in one sentence why creating simultaneous hashing solutions is not feasible, but (at least at the moment) it is considered to be an unsolved mathematical problem. Or, at least, so claimed the post which announced the sha1 collision experiment (here: https://tech.slashdot.org/stor...). To make it easier to understand why that is, a 1-bit will change X bits in sha-1 and Y bits in md5. Where, ideally, X and Y have a mean centered around half the length of the signature and have a high variance. X and Y should also be independent (as random variables). By comparison, a 1-bit change will produce a 100% predictable 1-bit change in CRC.
Because they can't make money off that position?
There's a big difference between using a cryptographic hash for things like security signing, and using one for generating a "content identifier"
is really a non sequitur. It's also a truism. Of course, there is a difference. If all you cared about was a "content identifier", you'd use CRC. But the reality is that you really want a secure content identifier (the one which does not provide a vector of attack on your system through spoofing of identifier through a simple calculation). Without it, you have a system in which it is trivial to create a haystack in which any one particular piece of content becomes a need to hide. All you need is to modify as many pieces of content as possible to collide with the one you want to be difficult to find.
The real answer he should have given is that any content which incorporates its md5 becomes unassailable because there is no known vector of attack to produce simultaneous md5 and sha1 collisions.
Did this man claim to be a member of some political group?
He clearly considers himself to be part of the American political group that hates/fears Islam. (Also part of the group who confuses all brown people with Middle Easterners, too, but that's not a political group.)
Was there any implication that this kind of violence would be repeated unless some public policy changed?
You don't have to be seeking a policy change to be seeking a political aim. Wanting to eject Muslims from the US is a political aim, and doing it by making them afraid they'll be shot is just as good as governmental action.
Why do you want access to *the* filesystem?
So I can control and organize my data.
If you don't like iCloud Drive, you can use Google Drive, Dropbox, OneDrive and a few others. I believe all of the rest of them give you the ability to use folders.
I don't want to give my data to a third party. I want to be able to control my own data. I have plenty of local storage, and no need or desire whatsoever to place my information in someone else's hands. If you want to do so, of course, by all means. For myself, I'd just as soon not enter into the lottery of "which cloud service will suffer a security breach next", or the lottery of "which cloud service is sharing data with government / corporations / hackers / employees", or the lottery of "geee, the Intertubes are down, I guess I can't get at my data", or the "you must look at ads or pay a fee to get at your data lottery", or the "I'm on a plane and so I can't get at my data lottery", etc., etc., etc.
It's up to you to decide which documents will be stored locally on the device.
Indeed it is. And the answer is "all of them", except where I have also stored them on some other device I own and wholly control.
Why is this not happening with pizzerias or sneakers?
It most definitely is. A decent quality pizza worth less than $2.00 (I make them from scratch, and that's what they cost me in low quantity in a relatively isolated region where raw materials prices are high, so I'm quite sure of the number) often costs well over $10.00. Sneakers worth about $8.00 can cost far, far more than that -- no more than a little bit of canvas, plastic and metal off a mass production line. The gouging is blatant and obvious. The fact that you are willing to actually write as if it wasn't reveals that you have no actual sense of the economics of either matter.
Why am I paying the same price for 75 Mbps up/down today, that I used to pay for 35 Mpbs up/down 6 years ago?
Because US broadband is lagging far behind the state of the art, and prices are far too high. You should be running much faster, and paying much less. Same was true six years ago. And you are not even at the bottom of the low performance / high price heap. In many places, it's worse.
The answer: competition.
No, the answer is collusion.
The Federal Communications Commission plans to halt implementation of a privacy rule that requires ISPs to protect the security of its customers' personal information.
Not that the FCC was ever very much more than a corporate puppet, but it's fascinating to watch them, and the government in general, find ways to be of even less service to the people.
So far, in just a couple months, we've seen the elimination of the requirement that energy companies must disclose royalties and government payments; the elimination of rules preventing dumping of coal mining waste into rivers and streams; the funneling of even more money into our "only more costly than the next eight countries put together" military; assertion that we need more and better nuclear weapons; suspension of an insurance rate cut for new Federal Housing Administration loans; completely unjustified disruption of already-issued visas; the installation of a white supremacist on the national security council; an order to "review" a rule requiring financial managers to act in their clients' best interests when handling retirement accounts; an "easing" of the Wall Street Reform and Consumer Protection Act of 2010; amplification of the drug war; amplification of the war against personal and consensual sexual choices; partisan filtering of the Whitehouse press pool; anti-free-press agitprop straight from the president... all this, along with a great deal of additional rhetoric that indicates more of this nature is likely on the way.
We no longer need turn to dystopian fiction to see just how badly our government can act out. A dystopian reality is rapidly establishing itself. The indicators are so strong at this point that some of the "peppers" are actually beginning to look like forward-thinkers.
I wonder just how much of this kind of damage the country can suffer before it undergoes some kind of seismic shift, or, if it will just deliquesce into a fully classist, corporatist nightmare.
I prefer to hope that the complacent have had a wake up call as to just how foolish and blind large segments of our population actually is; that they now understand that it is possible that without their active resistance, both at the voting booth and in general, all of this will continue apace while every tweet from President Trump, every bit of nonsense from Spicer and Conway, every craven abrogation of responsibility by congress, every unwise and harmful regulatory alteration, will be met with a blinkered nod-and-drool from the very people that saw to it that he reached the Oval Office — and that this will outright determine the future course of the country along these same destructive lines.
These are such very interesting times. We know we're not 1940's Germans; but we're finally going to get an answer as to whether we are better — or worse. I see little reason for optimism in this regard at this point in time, either.
The problem is that all these attempts to interest kids in STEM are so earnest and dull.
What we should be doing is tempting them with mad science. You see? It's not all death rays and monkey testicle implants.
It's important to hook them by middle school, when the all important sense of being misunderstood is its keenest.
About 1/3, according to statisticians.
The New York Times, the Los Angeles Times, Politico and BuzzFeed were also excluded from the meeting, which is known as a gaggle and is less formal than the televised Q-and-A session in the White House briefing room. The gaggle was held by White House press secretary Sean Spicer.
In a brief statement defending the move, administration spokeswoman Sarah Sanders said the White House "had the pool there so everyone would be represented and get an update from us today."
The pool usually includes a representative from one television network and one print outlet. In this case, four of the five major television networks — NBC, ABC, CBS and Fox News — were invited and attended the meeting, while only CNN was blocked.
And while The New York Times was kept out, conservative media organizations Breitbart News, The Washington Times and One America News Network were also allowed in.
Sounds to me like we actually DO know the answer now. It's not, otherwise this sample wouldn't have been destroyed when the diamond applying pressure to it broke.
Maybe it wasn't destroyed. Maybe it just rolled under the coffee table. I hope the dog didn't lick it up.
So out of 172 root CAs only 14 include any path length restrictions, and even the ones who do still allow some chaining.
I don't think the SHApocalypse will be tomorrow. This was an identical-prefix attack instead of a chosen-prefix which constrains the attacker considerably, and the computation required is much higher even to generate simple collisions. However, (again, please correct me if I'm missing something) it does seem plausible that that further weaknesses will be found which provide just enough leverage to forge a signature with one of those 172 CAs, and we may eventually see a rogue sha1WithRSAEncryption CA issued.
I concur, completely.
There are never any bugs you haven't found yet.