You are right of course, but if you would just store extremely long salts for that reason, it would make more sense to include a time delay between computations. Are such long salts used in practice?
It just protects from precomputation of the hash values of the passwords. If there were no salts then the hash value of a given password would look the same in every database (if the same hash function was used). So if you would precompute a rainbow table, where you store the password next to the hash value of the password, you could attack every database easily in the same way by just comparing the hash values and using the password stored next to it in the rainbow table. Now, with salting we get a unique hash value even if the password stays the same, rendering precomputation useless. The salt, however, is stored in plaintext next to the hash value: (hash, salt).
This does obviously not keep an attacker from computing the hash value = hash(password + salt) - it just helps against rainbow tables.
If you would still want to precompute a rainbow table the amount of memory needed would make it impractical. With n bit salts you would have to store 2^n entries for each password.
You are misunderstanding it. Salting only protects from precomputed tables containing (password, hash) entries (rainbow tables) when using a unique salt. I didn't read TFA, but I assume this is a simple brute-force attack. The attacker would just add the salt to each guess, which does not make it any more difficult.
The 5 remaining SHA-3 candidates, however, are new designs. The current SHA algorithms (up to SHA-512) are based on MD4 and have some operations added to incorporate the higher number of message blocks into the hash.
MD4, and MD5 have been badly broken years ago. Some collisions were even calculated by hand. SHA-1 was under heavy attack before the SHA-3 competition started, but there have not been any collisions found yet. Bart Preneel has a great slide as an overview of the state of hash functions based on MD4: http://homes.esat.kuleuven.be/~preneel/preneel_hash_icics10v1.pdf (slide 46)
I guess the article refers to the Nordschleife layout? 9 minutes would be awful around the GP layout, but it would be great around the combined layout... (Nürburgring)
As the article is only shiny pictures and almost no information it is hard to tell.
So you mean it is not Sony's fault then? Because if I remember correctly their random number usage was totally flawed and therefore it was no real challenge.
Drugs shouldn't have much to do with nuclear energy safety. Moreover, if you start asking about coal mine accidents, you should also consider uranium mining accidents. I have to admit I didn't find much about any accidents, but there are a few. (and probably I would have found more if I had been looking harder)
Of course, with nuclear energy you often can't directly find correlation with accidents. What about permanent disposal. How do you know everything will be OK with the nuclear waste we have produced up to now. It has only been a few decades of nuclear energy, so it will take some time before these materials are not dangerous any more.
I didn't read TFA, but why is Watchmen considered a box-office disappointment? According to this it grossed $185 million and had a budget of $130 million.
As the page is slashdotted, I just wanted to post how it is done here:
For GMail, he added an image to his own GMail account, which he set to "visible for everyone". On his own site he added an invisible img and tries to access the image in his GMail account. He then triggers a javascript function depending on the outcome of the img inclusion (onload or onerror), so he can make the decision, if the visitor of his website is logged in to GMail.
For Facebook, Twitter and Digg he uses http status codes. He tries to access some URL (https://www.facebook.com/imike3) via javascript and depending on the status code he gets, he can decide whether you are logged in or not. This attack doesn't work with IE or Opera, because they do not trigger the onload/onerror events when receiving invalid js.
Slashdot Mirror
Will this be news everytime a new device is targeted?
ah, i was stupid - time delay obviously makes no sense in offline cracking
You are right of course, but if you would just store extremely long salts for that reason, it would make more sense to include a time delay between computations. Are such long salts used in practice?
It just protects from precomputation of the hash values of the passwords. If there were no salts then the hash value of a given password would look the same in every database (if the same hash function was used). So if you would precompute a rainbow table, where you store the password next to the hash value of the password, you could attack every database easily in the same way by just comparing the hash values and using the password stored next to it in the rainbow table.
Now, with salting we get a unique hash value even if the password stays the same, rendering precomputation useless. The salt, however, is stored in plaintext next to the hash value: (hash, salt).
This does obviously not keep an attacker from computing the hash value = hash(password + salt) - it just helps against rainbow tables.
If you would still want to precompute a rainbow table the amount of memory needed would make it impractical. With n bit salts you would have to store 2^n entries for each password.
You are misunderstanding it. Salting only protects from precomputed tables containing (password, hash) entries (rainbow tables) when using a unique salt. I didn't read TFA, but I assume this is a simple brute-force attack. The attacker would just add the salt to each guess, which does not make it any more difficult.
The 5 remaining SHA-3 candidates, however, are new designs. The current SHA algorithms (up to SHA-512) are based on MD4 and have some operations added to incorporate the higher number of message blocks into the hash.
MD4, and MD5 have been badly broken years ago. Some collisions were even calculated by hand. SHA-1 was under heavy attack before the SHA-3 competition started, but there have not been any collisions found yet. Bart Preneel has a great slide as an overview of the state of hash functions based on MD4: http://homes.esat.kuleuven.be/~preneel/preneel_hash_icics10v1.pdf (slide 46)
Yes, but it could also be the combined layout. It is unlikely because Nordschleife is driven usually, but you can't be sure because of that.
I guess the article refers to the Nordschleife layout? 9 minutes would be awful around the GP layout, but it would be great around the combined layout ... (Nürburgring)
As the article is only shiny pictures and almost no information it is hard to tell.
And don't forget your towel.
I never leave my house without my towel and the "Hitchhiker's Guide to the Galaxy".
So you mean it is not Sony's fault then? Because if I remember correctly their random number usage was totally flawed and therefore it was no real challenge.
Obligatory http://xkcd.com/221/
You are comparing apples to oranges.
Drugs shouldn't have much to do with nuclear energy safety. Moreover, if you start asking about coal mine accidents, you should also consider uranium mining accidents. I have to admit I didn't find much about any accidents, but there are a few. (and probably I would have found more if I had been looking harder) Of course, with nuclear energy you often can't directly find correlation with accidents. What about permanent disposal. How do you know everything will be OK with the nuclear waste we have produced up to now. It has only been a few decades of nuclear energy, so it will take some time before these materials are not dangerous any more.
Even more awesome, Steven Seagal.
http://www.youtube.com/watch?v=YMu2xNBpyQc
Privacy problems aside: So basically these "tiny transistors" are RFID chips?
From TFA:
These low-voltage transistors could one day provide added security or tracking by transmitting information wirelessly to a scanner.
Security for whom btw? For the banks I assume?
I think manufacturers could be forced to do it. The same way they have been forced to use the same type of phone chargers by the EU.
... Facebook
I didn't read TFA, but why is Watchmen considered a box-office disappointment? According to this it grossed $185 million and had a budget of $130 million.
Exactly. It's just awful, how slowly things are evolving in these locked down mobile systems.
As long as he only drops bananas ...
Man, I hate those red turtles!
As the page is slashdotted, I just wanted to post how it is done here:
For GMail, he added an image to his own GMail account, which he set to "visible for everyone". On his own site he added an invisible img and tries to access the image in his GMail account. He then triggers a javascript function depending on the outcome of the img inclusion (onload or onerror), so he can make the decision, if the visitor of his website is logged in to GMail.
For Facebook, Twitter and Digg he uses http status codes. He tries to access some URL (https://www.facebook.com/imike3) via javascript and depending on the status code he gets, he can decide whether you are logged in or not. This attack doesn't work with IE or Opera, because they do not trigger the onload/onerror events when receiving invalid js.