4 ms·

I'm not sure what you mean by "the crypto is not ideal"? I was under the impression that there are not yet collisions for SHA-256 https://github.com/ipfs/faq/is

I'm not sure what you mean by "the crypto is not ideal"? I was under the impression that there are not yet collisions for SHA-256 https://github.com/ipfs/faq/issues/22 https://github.com/ipfs/faq/issues/22 Only for SHA-1 (which has 160 bit hashes) https://en.wikipedia.org/wiki/SHA-1#Attacks https://en.wikipedia.org/wiki/SHA-1#Attacks

red_admiral 9y ago
The attack mentioned on the page is brute-forcing someone's details from partial information: "it can be used to “fill the gaps” of information about any citizen. If you know someone’s birth date and the area where they live, you can obtain their government ID by trial-and-error on that website." The mitigation is slowing down the number of guesses/second that an attacker can try. In a well-designed key derivation function, an attacker with 100x the resources should only be able to try out guesses 100x as fast. That's what scrypt/argon2/bcrypt/PBKDF2/... try and achieve. SHA and other general-purpose hash functions tend to be easy to parallelize, at least in parts, and you can get huge speedups on GPUs or even better, FPGAs/ASICs. That's why no-one serious still mines bitcoins on CPUs and the big mining syndicates [hire planes](http://uk.businessinsider.com/cryptocurrency-miners-rent-boeing-747s-2017-7 http://uk.businessinsider.com/cryptocurrency-miners-rent-boe...) to ship GPUs a little bit faster. This has nothing to do with collisions. It's to do with hash functions being designed to be fast, and key derivation functions are designed to be slow and memory-hard.
- timthelion 9y ago
  Thanks for the clarification. That makes sense now.
- samstave 9y ago
  Holy shit! People are hiring planes to ship them GPUs!? Jeasus!! Gibson was far more prescient than acknowledged; "the future is already here, but not evenly distributed yet" Wow... I had such opportunity and ability to buy bitcoins in 2012... and I missed that boat.
  - rangibaby 9y ago
    I downloaded the Bitcoin mining app in 2010, opened it once, got bored of waiting for it to sync with some server, then shut and forgot about it for a few years. It might be a funny story to tell my grandkids if BTC is still around
    - saimiam 9y ago
      If Bitcoin is around when your grandkids are of age, even this minute might be a great time to buy Bitcoin. Why miss the same boat twice?
      - kebman 9y ago
        Hope what you say is true, because I bought bitcoin @ $4700 :'(
      - unkown-unknowns 9y ago
        Like they say; "The best time to buy bitcoin was yesterday. The next-best time to buy bitcoin is now."
  - ameliaquining 9y ago
    This isn't as big a deal as it sounds. https://news.ycombinator.com/item?id=14887929 https://news.ycombinator.com/item?id=14887929
  - sneak 9y ago
    No, they’re not. They’re just overnighting large shipments of GPUs with carriers that use airplanes to handle overnight shipping. That quote also isn’t from Gibson. :)
  - runeks 9y ago
    > I had such opportunity and ability to buy bitcoins in 2012... and I missed that boat. You also have opportunity and ability to buy bitcoins now. And, just like in 2012, you have no idea what the price will be five years into the future.
- cvwright 9y ago
  Yup. For one example of a software package that can use GPUs to accelerate password cracking and hash brute forcing, folks can look at hashcat: https://hashcat.net/hashcat/ https://hashcat.net/hashcat/

red_admiral 9y ago

The attack mentioned on the page is brute-forcing someone's details from partial information: "it can be used to “fill the gaps” of information about any citizen. If you know someone’s birth date and the area where they live, you can obtain their government ID by trial-and-error on that website." The mitigation is slowing down the number of guesses/second that an attacker can try. In a well-designed key derivation function, an attacker with 100x the resources should only be able to try out guesses 100x as fast. That's what scrypt/argon2/bcrypt/PBKDF2/... try and achieve. SHA and other general-purpose hash functions tend to be easy to parallelize, at least in parts, and you can get huge speedups on GPUs or even better, FPGAs/ASICs. That's why no-one serious still mines bitcoins on CPUs and the big mining syndicates [hire planes](http://uk.businessinsider.com/cryptocurrency-miners-rent-boeing-747s-2017-7 http://uk.businessinsider.com/cryptocurrency-miners-rent-boe...) to ship GPUs a little bit faster. This has nothing to do with collisions. It's to do with hash functions being designed to be fast, and key derivation functions are designed to be slow and memory-hard.

timthelion 9y ago
Thanks for the clarification. That makes sense now.
samstave 9y ago
Holy shit! People are hiring planes to ship them GPUs!? Jeasus!! Gibson was far more prescient than acknowledged; "the future is already here, but not evenly distributed yet" Wow... I had such opportunity and ability to buy bitcoins in 2012... and I missed that boat.
- rangibaby 9y ago
  I downloaded the Bitcoin mining app in 2010, opened it once, got bored of waiting for it to sync with some server, then shut and forgot about it for a few years. It might be a funny story to tell my grandkids if BTC is still around
  - saimiam 9y ago
    If Bitcoin is around when your grandkids are of age, even this minute might be a great time to buy Bitcoin. Why miss the same boat twice?
    - kebman 9y ago
      Hope what you say is true, because I bought bitcoin @ $4700 :'(
    - unkown-unknowns 9y ago
      Like they say; "The best time to buy bitcoin was yesterday. The next-best time to buy bitcoin is now."
- ameliaquining 9y ago
  This isn't as big a deal as it sounds. https://news.ycombinator.com/item?id=14887929 https://news.ycombinator.com/item?id=14887929
- sneak 9y ago
  No, they’re not. They’re just overnighting large shipments of GPUs with carriers that use airplanes to handle overnight shipping. That quote also isn’t from Gibson. :)
- runeks 9y ago
  > I had such opportunity and ability to buy bitcoins in 2012... and I missed that boat. You also have opportunity and ability to buy bitcoins now. And, just like in 2012, you have no idea what the price will be five years into the future.
cvwright 9y ago
Yup. For one example of a software package that can use GPUs to accelerate password cracking and hash brute forcing, folks can look at hashcat: https://hashcat.net/hashcat/ https://hashcat.net/hashcat/