5 ms·

The SHA-256 hashes are gpg signed with the key at https://bitcoin.org/laanwj-releases.asc https://bitcoin.org/laanwj-releases.asc Nobody actually checks the ex

The SHA-256 hashes are gpg signed with the key at https://bitcoin.org/laanwj-releases.asc https://bitcoin.org/laanwj-releases.asc Nobody actually checks the executable signatures, they're buried in the file properties.

garmaine 5y ago
Everyone on macOS and Windows checks the executable signatures automatically on first run.
- ddtaylor 5y ago
  Can't an attacker modify the executable to not do that?
  - freeone3000 5y ago
    No, because the check isn't part of the executable, it's part of the operating system. An attacker would have to modify the executable to have a valid certificate, which would take several months and a few hundred dollars, which usually makes it not worth it.
    - tinus_hn 5y ago
      The alternative is signing it with another certificate which is about $100
      - freeone3000 5y ago
        From who? It can't be a non-EV cert, since those are trusted less and present the same dialog. A 1-year from Verisign is $500. Comodo is $229. Setigo is $329. All of them require verification that you own a business, which is another $50 to set up an LLC, and the issuance lead time for both of these providers are a few months. If you have a quick, trusted way of getting an EV code-signing cert trusted by SmartScreen, please, let me know.
        tinus_hn 5y ago
        They do present a dialog but not the same one you get with no or an invalid signature.
h_anna_h 5y ago
Signing the hashes instead of the executable leaves you open to collision attacks.
- gojomo 5y ago
  Are you aware of any practical SHA-256 collision attacks? What do you expect the results would be, if within the next few days it were discovered that there were two different files, with the same SHA-256, each claiming to be the Bitcoin-0.21.1 release?
  - nullc 5y ago
    If you know a sha256 collision the bitcoin network will currently pay you about 0.476 BTC (~about $26k USD right now) to publish it. https://blockstream.info/address/35Snmmy3uhaer2gTboc81ayCip4m9DT4ko https://blockstream.info/address/35Snmmy3uhaer2gTboc81ayCip4... https://blockstream.info/address/39VXyuoc6SXYKp9TcAhoiN1mb4ns6z3Yu6 https://blockstream.info/address/39VXyuoc6SXYKp9TcAhoiN1mb4n... https://blockstream.info/address/3DUQQvz4t57Jy7jxE86kyFcNpKtURNf1VW https://blockstream.info/address/3DUQQvz4t57Jy7jxE86kyFcNpKt...
    - drexlspivey 5y ago
      In practice, if you try to claim those coins by broadcasting a transaction with the collision the most likely outcome is someone will snatch the coins by changing the output address with his own address (since the scripts contains no signature checking). You would have to give your tx straight to a miner (and hope for the best)
      - gojomo 5y ago
        But also, in practice, the fame of announcing such a discovery (with or without an explanation of the method for creating it) could be worth more than $26k. And if you wanted to profit from it, via submitting the transaction or not, you could likely make far more by speculating on the effects of that announced collision on the Bitcoin price – likely sharply negative.

garmaine 5y ago

Everyone on macOS and Windows checks the executable signatures automatically on first run.

ddtaylor 5y ago
Can't an attacker modify the executable to not do that?
- freeone3000 5y ago
  No, because the check isn't part of the executable, it's part of the operating system. An attacker would have to modify the executable to have a valid certificate, which would take several months and a few hundred dollars, which usually makes it not worth it.
  - tinus_hn 5y ago
    The alternative is signing it with another certificate which is about $100
    - freeone3000 5y ago
      From who? It can't be a non-EV cert, since those are trusted less and present the same dialog. A 1-year from Verisign is $500. Comodo is $229. Setigo is $329. All of them require verification that you own a business, which is another $50 to set up an LLC, and the issuance lead time for both of these providers are a few months. If you have a quick, trusted way of getting an EV code-signing cert trusted by SmartScreen, please, let me know.
      - tinus_hn 5y ago
        They do present a dialog but not the same one you get with no or an invalid signature.

h_anna_h 5y ago

Signing the hashes instead of the executable leaves you open to collision attacks.

gojomo 5y ago
Are you aware of any practical SHA-256 collision attacks? What do you expect the results would be, if within the next few days it were discovered that there were two different files, with the same SHA-256, each claiming to be the Bitcoin-0.21.1 release?
- nullc 5y ago
  If you know a sha256 collision the bitcoin network will currently pay you about 0.476 BTC (~about $26k USD right now) to publish it. https://blockstream.info/address/35Snmmy3uhaer2gTboc81ayCip4m9DT4ko https://blockstream.info/address/35Snmmy3uhaer2gTboc81ayCip4... https://blockstream.info/address/39VXyuoc6SXYKp9TcAhoiN1mb4ns6z3Yu6 https://blockstream.info/address/39VXyuoc6SXYKp9TcAhoiN1mb4n... https://blockstream.info/address/3DUQQvz4t57Jy7jxE86kyFcNpKtURNf1VW https://blockstream.info/address/3DUQQvz4t57Jy7jxE86kyFcNpKt...
  - drexlspivey 5y ago
    In practice, if you try to claim those coins by broadcasting a transaction with the collision the most likely outcome is someone will snatch the coins by changing the output address with his own address (since the scripts contains no signature checking). You would have to give your tx straight to a miner (and hope for the best)
    - gojomo 5y ago
      But also, in practice, the fame of announcing such a discovery (with or without an explanation of the method for creating it) could be worth more than $26k. And if you wanted to profit from it, via submitting the transaction or not, you could likely make far more by speculating on the effects of that announced collision on the Bitcoin price – likely sharply negative.