Speaking as someone that teaches second semester CS to 300 undergrads a semester, there is value in both.
Advantage Paper: The computer is a crutch. If you know it, you can write it. You are going to to have to do this in coding interviews. Requires no infrastructure to give an exam without cheating. (I actually don't have the space/computers to give a computer exam to hundreds of students at a time.)
Advantage Computer: I/TAs don't have to grade it, I can just use gradescope.com and students won't argue with me for partial credit.
It was a frustrating experience for sure, but there is an easy solution: switch to any one of the MVNOs or a prepaid plan from the carrier. Figure out what network they are riding on top of that matches your preference, then switch.
I picked GoPhone (from ATT), but straighttalk wireless, or others will work just fine for you and are likely cheaper.
There is a fairly straightforward way to locate the cameras if you have a bit more time than me. Using the time of the sunrise and sunset (and the length of the day), you should be able to get a decent fix on the location (people use the same technique on whales and sea turtles.)
But when you get down to it, churn is your biggest enemy. If you look at the rate at which people join and leave p2p networks, the amount of replication you need to do can use a lot of bandwidth. Every time a user quits (or drive crashes etc.) all of the data they were storing for others must be replicated again. If they aren't available online for a while you have to assume they have left the network and replicate proactively. See the paper for a few sample calculations based on the churn found in systems like kazaa and skype.
As with any news article, it is trying to explain the concepts to a general audience. This always leads to misconceptions about what the technical solutions and problems are. Primarily, DTNs are not designed to "fix" the internet, it is designed to deal with disruptions at the edges, and to deal with challenged networking environments (primarily mobile ones). If you are interested in some technical information (some shameless self-promotion as the DieselNet project mentioned in the article belongs to myself and my colleague).
Ok some quick estimates using the article. Someone check my math:)
The article claims it can produce 1MW per 10 acres. Assuming year round, 24hour production. 1e6 J/s *(365*24*3600 sec/year)/10 acres=31.5e11 Joules/year/acre.
I found an article that says the US produces 71.6 quadrillion BTUs/year. 71.6e15*1055 J/BTU=75e18 Joules/year.
So we need (75e18 Joules/year) / (31.5e11 Joules/year/acre) = 24e6 acres. Only 1/7th the total area of Texas. Not too shabby!!
These are really great questions. Administration is something that we have considered, however details like that don't usually make it into the paper.
The master key should always be escrowed. This allows the admin to create a new token. The real problem arrises when the user is on the road. The best answer may be that the user can enter the master-key manually, after an admin reads it to him over the phone.
The loss of the token is a threat. We noted a few details on this in the paper. You need to put a PIN into the device on an infrequent basis. (Once a day or week). That limits the vulnerability in time, however that is pretty unsettling considering that the entire disk could be copied in that period! Instead the best solution is something that detect that you took the device off and requires the PIN again. Biometrics may be one answer, however detecting a break in the continuity of the clasp may be another.
The article isn't wrong, just vague. For more details see the paper.
However, what you describe is almost precisely how it works. The "walking away encryption" is only for the file CACHE in memory. The alternative is to bzero the cache which takes a lot less time. Unfortunately, recovery is equivalent to a cold cache which may annoy users with a lot of disk i/o.
The data always sits on the disk encrypted. Otherwise reencrypting it would take forever.
As much as I enjoy the free publicity, this has been posted on slashdot before.
To correct a serious error that appears in this article and in the nytimes article this was cribbed from: The system was NEVER run on the IBM watch. We mentioned it as a possibility and somehow it was taken as fact.
I welcome the comments on the work, however remember that the world of university research is often more forward looking than the commercial world. That is our job!
Re:Still no S/MIME plugins. Thank you, move along
on
PINE Releases 4.50
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· Score: 1
Admittedly, I haven't actually *tried* it, but it looks like it can take care of your problem:
As always it is difficult to discern the technical details of how a system works from a news article. If you are interested, I urge you to read the technical paper.
My papers
FYI, the data sits on the disk encrypted and in the page cache decrypted. Keep in mind this is a technical paper and a research prototype and not a product.
Slashdot Mirror
Speaking as someone that teaches second semester CS to 300 undergrads a semester, there is value in both.
Advantage Paper: The computer is a crutch. If you know it, you can write it. You are going to to have to do this in coding interviews. Requires no infrastructure to give an exam without cheating. (I actually don't have the space/computers to give a computer exam to hundreds of students at a time.)
Advantage Computer: I/TAs don't have to grade it, I can just use gradescope.com and students won't argue with me for partial credit.
What does the inside of a used implantable defib smell like? I know Kevin knows :)
It was a frustrating experience for sure, but there is an easy solution: switch to any one of the MVNOs or a prepaid plan from the carrier. Figure out what network they are riding on top of that matches your preference, then switch.
I picked GoPhone (from ATT), but straighttalk wireless, or others will work just fine for you and are likely cheaper.
Good luck, but this is an easy one to solve.
That's why I use freemyapps (But then again I work there so I might be *slightly* biased :)
There is a fairly straightforward way to locate the cameras if you have a bit more time than me. Using the time of the sunrise and sunset (and the length of the day), you should be able to get a decent fix on the location (people use the same technique on whales and sea turtles.)
On paper it is mostly a great idea.
We had a paper on some tricks to play in file systems to make it perform better:
http://prisms.cs.umass.edu/mcorner/papers/fast_2007_tfs.pdf
But when you get down to it, churn is your biggest enemy. If you look at the rate at which people join and leave p2p networks, the amount of replication you need to do can use a lot of bandwidth. Every time a user quits (or drive crashes etc.) all of the data they were storing for others must be replicated again. If they aren't available online for a while you have to assume they have left the network and replicate proactively. See the paper for a few sample calculations based on the churn found in systems like kazaa and skype.
-M
As with any news article, it is trying to explain the concepts to a general audience. This always leads to misconceptions about what the technical solutions and problems are. Primarily, DTNs are not designed to "fix" the internet, it is designed to deal with disruptions at the edges, and to deal with challenged networking environments (primarily mobile ones). If you are interested in some technical information (some shameless self-promotion as the DieselNet project mentioned in the article belongs to myself and my colleague).
http://prisms.cs.umass.edu/dome
http://www.dtnrg.org/
If you want to know more, there are a ton of good papers being published in networking conferences on DTNs
Ok some quick estimates using the article. Someone check my math :)
The article claims it can produce 1MW per 10 acres. Assuming year round, 24hour production. 1e6 J/s *(365*24*3600 sec/year)/10 acres=31.5e11 Joules/year/acre.
I found an article that says the US produces 71.6 quadrillion BTUs/year. 71.6e15*1055 J/BTU=75e18 Joules/year.
So we need (75e18 Joules/year) / (31.5e11 Joules/year/acre) = 24e6 acres. Only 1/7th the total area of Texas. Not too shabby!!
These are really great questions. Administration is something that we have considered, however details like that don't usually make it into the paper.
The master key should always be escrowed. This allows the admin to create a new token. The real problem arrises when the user is on the road. The best answer may be that the user can enter the master-key manually, after an admin reads it to him over the phone.
The loss of the token is a threat. We noted a few details on this in the paper. You need to put a PIN into the device on an infrequent basis. (Once a day or week). That limits the vulnerability in time, however that is pretty unsettling considering that the entire disk could be copied in that period! Instead the best solution is something that detect that you took the device off and requires the PIN again. Biometrics may be one answer, however detecting a break in the continuity of the clasp may be another.
Thanks for the questions.
The article isn't wrong, just vague. For more details see the paper.
However, what you describe is almost precisely how it works. The "walking away encryption" is only for the file CACHE in memory. The alternative is to bzero the cache which takes a lot less time. Unfortunately, recovery is equivalent to a cold cache which may annoy users with a lot of disk i/o.
The data always sits on the disk encrypted. Otherwise reencrypting it would take forever.
As much as I enjoy the free publicity, this has been posted on slashdot before.
To correct a serious error that appears in this article and in the nytimes article this was cribbed from: The system was NEVER run on the IBM watch. We mentioned it as a possibility and somehow it was taken as fact.
I welcome the comments on the work, however remember that the world of university research is often more forward looking than the commercial world. That is our job!
Admittedly, I haven't actually *tried* it, but it looks like it can take care of your problem:
http://home.freeuk.net/p.brooke/topal/
As always it is difficult to discern the technical details of how a system works from a news article. If you are interested, I urge you to read the technical paper. My papers
FYI, the data sits on the disk encrypted and in the page cache decrypted. Keep in mind this is a technical paper and a research prototype and not a product.
Because asymmetric encryption is 1000 times slower than symmetric algorithms (According to Schneier, approx based on some example algorithms)