He didn't say they weren't different. He said people think that vinyl is "more genuine" or "more accurate" than digital. Genuine is a weasel word -- it's ill-defined. (Probably the most reasonable definition here is "closest to how the creator of the music intended for you to hear it". But, I digress. It's hard to measure.) Vinyl is certainly less accurate than a good digital representation.

It can be different, though, because it introduces flaws that the digital representation doesn't have. Maybe those flaws make the music "better" in some sense, but not "more accurate".

They're replayable.

You don't. Your field of vision through the back window is tiny compared to the field of vision of the camera.

I thought they were a stupid gimmick until I got a car with one. Now I curse every time I drive a car that doesn't have one, because backing up is a lot harder.

He wasn't making an analogy between how you find a hash collision and how you win the lottery -- only comparing the odds.

Dropbox uses SHA-256 hashes. I'm assuming this is what they use for this feature, since it's what they use internally for file identification and deduplication. They actually hash 2 MB file chunks, which means that any file more than 2 MB produces multiple hashes (one per chunk, naturally).

The "many chances of winning" you're referring to here is the birthday collision problem. A good, rough approximation is that for an N-bit hash, while the number of different hashes is 2^N, the number you can generate before risking a collision is about 2^(N/2). So, with SHA-256, we run no significant risk of collision until we've generated around 2^128 ~= 10^38 hashes.

The total amount of data stored worldwide is on the order of 1 ZB. That's room enough for about 10^15 2-MB chunks. Of course, some of our files might be smaller than this 2 MB chunk size, enabling us to be more efficient with storage. We might be able to get somewhere around 10^20 different files in there.

That's a strange and untenable use of all of the world's storage, and it still puts us about 18 orders of magnitude short of being able to risk a SHA-256 collision. If you had this giant set of a ton of different files, the probability of a collision existing is about 1 in 10^37.

So, short of a flaw in SHA-256, you can assume that a hash collision will never happen. We know of no such flaws. (If we do, it will almost certainly be the case that the collision only occurs because one of the two files was specifically manipulated to produce the collision.)

On the other hand, the odds of winning the lottery are rarely worse than 1 in 10^9.

In the same sense that receiving them from you, storing them, or transmitting them to others (at your request) is "going through" your files.

Dropbox already uses SHA-256 hashes internally for file identification and deduplication. So it's been hashing all of your data this whole time.

The function of salt is to make password cracking efforts more difficult when the attacker has access to the site's password database. So, predictability is not as important, since all the listed information is available to the attacker anyway. (Similarly, the salts are available to the attacker.) That doesn't look like much entropy, though. Really, storing an extra column of random, per-user salts in a database is not particularly hard and has tangible (though not magical) benefits.

Yeah. IMO, usernames should never be relied on for security. Just assume an attacker can determine what usernames are taken and which aren't, and further assume that an attacker with a particular target can figure out the username for that target. (Unless pseudonymity is a key design aspect of your system.)

They're not talking about a fixed value that's different from "+123456". They're talking about using a different, random value for each user. That is more secure. (There's still plenty of security problems, but it's better than every user's password being completely predictable.)

Of course, if you're bothering to store a different random value for each user, there's no reason to include their username in the password. Just store a long random password for each user. (That's still not great security -- never mind that the password is exposed in cleartext and transmitted over HTTP -- because a user can't change a compromised password.)

It looks from the video that the password is simply the username concatenated with a global string, "123456".

That's not salt. That's not what the word means. A salt is data that is not part of the password but is combined with the password when hashed. The client side never sees salt.

So all these discussions of salt are not at all relevant.

This is fundamentally a case of hard-coded credentials, which is more stupid than a non-random salt. (Also, really, transmitting credentials over HTTP?)

Absolutely. It's just a question of whether their incompetence happened to be the cause here.

Tomato, tomato.

Normally I'd agree, but the article summarizes a collection of studies, so is a work by itself. To skip the article, you'd either need to just link a number of studies and skip any useful summary of them, or you'd need to reproduce the summary in the article (which would be plagiarism, or at least wasted effort).

Orbital energy. Or, you know, just forward motion.

Rotational energy maintains the night/day cycle.

True, they're not equal. To a reasonable approximation, they are equal: the heat picked up via global warming is tiny compared to the amount of heat added by the Sun each day (and subsequently lost to space by radiation).

True, though it's mostly infrared and albedo.

No, but a distribution of radiation does. When, in physics, someone says that radiation is "X Kelvin", it's shorthand for "a distribution of radiation very close to the ideal black-body radiation at X Kelvin". The great bulk of the Sun's and Earth's radiation is black-body radiation.

Radiation certainly does have entropy. See, for example, Planck's "the Theory of Heat Radiation" or some more modern text.

This is just a misunderstanding of the meaning of 6000K vs. 300K light. Though it's incorrect to just assume zero entropy at 0K.

It's enormously more complicated than that. That's a Brian-Greene-level description.

... Are you an engineer?

Super usable! And it's not like it ignores the hardest problem, with is operating PKI properly.

That's true. The messages really are never encrypted at all. :-)