4 ms·

Is there a fundamental issue with crypto in JS (side-channel attacks?) or is it just that available crypto libraries in JS are immature?

cjg 9y ago
The normal complaint about crypto in JS is that, as a user, I cannot tell what JS is going to be delivered to me this time. Perhaps a security letter forced an update to broken crypto.
- twiss 9y ago
  In Airborn.io, I've solved this by installing some code in a Service Worker, which verifies all updates: http://blog.airbornos.com/post/2017/08/03/Transparent-Web-Apps-using-Service-Worker http://blog.airbornos.com/post/2017/08/03/Transparent-Web-Ap... The SW stays installed for when you open the web app the next time, in essence making it a trust-on-first-use scheme. I'm working on a library: https://github.com/airbornio/signed-web-apps https://github.com/airbornio/signed-web-apps It would be cool if other web apps (including Graphite?) could implement it too.
- tasn 9y ago
  Shameless plug: I created a browser extension to solve just that: https://github.com/tasn/webext-signed-pages/ https://github.com/tasn/webext-signed-pages/ It lets devs PGP sign their web apps and verifies those signatures. We use it for the EteSync (https://www.EteSync.com https://www.EteSync.com) web client.
- saas_co_de 9y ago
  This is solved: https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity https://developer.mozilla.org/en-US/docs/Web/Security/Subres... If you really care you can check the integrity hash on your scripts before using every time. That gives you more security than the update in your OS or Browser so they are a weaker link.
  - peterwwillis 9y ago
    From https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2011/august/javascript-cryptography-considered-harmful/ https://www.nccgroup.trust/us/about-us/newsroom-and-events/b... "OK, THEN I'LL JUST SERVE A CRYPTOGRAPHIC DIGEST OF MY CODE FROM THE SAME SERVER SO THE CODE CAN VERIFY ITSELF." "This won't work." Your comment that "That gives you more security than the update in your OS or Browser" is patently false, I don't know why you'd suggest that.
    - saas_co_de 9y ago
      > THEN I'LL JUST SERVE A CRYPTOGRAPHIC DIGEST OF MY CODE 1) Javascript is open source and you can audit the code you are running. 2) You can save the HTML of a page and run your local copy so that you know the JS can't change or check the hash every time Can you audit the code of your OS or Browser? In theory, if you are on Linux, but in practice it is too complex and voluminous for one person to do. A browser based app is usually in the thousands of lines of open source code running in a sandbox that is very easy to debug. The browser environment is the most secure and most easily user auditable environment there is. Unless you expect all of your users to build your app from source on linux that they built from source you can't really get better security. "Javascript Cryptography Considered Harmful" is old FUD. It was barely coherent when first published and the only legitimate arguments it had have been fixed.
      - deleted 9y ago
        [deleted]
      - webmaven 9y ago
        > Unless you expect all of your users to build your app from source on linux that they built from source You forgot to tack on "using compilers, etc., that they also built from source".
peterwwillis 9y ago
This explains it: https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2011/august/javascript-cryptography-considered-harmful/ https://www.nccgroup.trust/us/about-us/newsroom-and-events/b...
- explorigin 9y ago
  Please stop propagating this article. Its positions are out of date. FTA: WHAT'S HARD ABOUT DEPLOYING JAVASCRIPT OVER SSL/TLS? You can't simply send a single Javascript file over SSL/TLS. You have to send all the page contentover SSL/TLS. Otherwise, attackers will hijack the crypto code using the least-secure connection that builds the page. ---- Seriously? Serving entire websites over https is the norm these days. It appears as though the article has been added to but not updated. Current advocates should re-read the article.
  - peterwwillis 9y ago
    There's like 30 different points in this article.
    - deleted 9y ago
      [deleted]
    - explorigin 9y ago
      Yes, I didn't really want to go through each point in the article. But here's a few things to consider as you read it: - The article reads like those arguments we have in our heads where we always win. - The article is from 2011 - The article says "come back in 10 years when people aren't running browsers from 2008" (we're not to 2021 yet but the majority of browsers are evergreen now) - We have SubtleCrypto now - We have SubResourceIntegrity - We have CORS and CSP The article has some valid points, but I posit that it is more harmful than helpful. We need an Mozilla-style "arewesecureyet" website instead.
      - peterwwillis 9y ago

cjg 9y ago

The normal complaint about crypto in JS is that, as a user, I cannot tell what JS is going to be delivered to me this time. Perhaps a security letter forced an update to broken crypto.

twiss 9y ago
In Airborn.io, I've solved this by installing some code in a Service Worker, which verifies all updates: http://blog.airbornos.com/post/2017/08/03/Transparent-Web-Apps-using-Service-Worker http://blog.airbornos.com/post/2017/08/03/Transparent-Web-Ap... The SW stays installed for when you open the web app the next time, in essence making it a trust-on-first-use scheme. I'm working on a library: https://github.com/airbornio/signed-web-apps https://github.com/airbornio/signed-web-apps It would be cool if other web apps (including Graphite?) could implement it too.
tasn 9y ago
Shameless plug: I created a browser extension to solve just that: https://github.com/tasn/webext-signed-pages/ https://github.com/tasn/webext-signed-pages/ It lets devs PGP sign their web apps and verifies those signatures. We use it for the EteSync (https://www.EteSync.com https://www.EteSync.com) web client.
saas_co_de 9y ago
This is solved: https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity https://developer.mozilla.org/en-US/docs/Web/Security/Subres... If you really care you can check the integrity hash on your scripts before using every time. That gives you more security than the update in your OS or Browser so they are a weaker link.
- peterwwillis 9y ago
  From https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2011/august/javascript-cryptography-considered-harmful/ https://www.nccgroup.trust/us/about-us/newsroom-and-events/b... "OK, THEN I'LL JUST SERVE A CRYPTOGRAPHIC DIGEST OF MY CODE FROM THE SAME SERVER SO THE CODE CAN VERIFY ITSELF." "This won't work." Your comment that "That gives you more security than the update in your OS or Browser" is patently false, I don't know why you'd suggest that.
  - saas_co_de 9y ago
    > THEN I'LL JUST SERVE A CRYPTOGRAPHIC DIGEST OF MY CODE 1) Javascript is open source and you can audit the code you are running. 2) You can save the HTML of a page and run your local copy so that you know the JS can't change or check the hash every time Can you audit the code of your OS or Browser? In theory, if you are on Linux, but in practice it is too complex and voluminous for one person to do. A browser based app is usually in the thousands of lines of open source code running in a sandbox that is very easy to debug. The browser environment is the most secure and most easily user auditable environment there is. Unless you expect all of your users to build your app from source on linux that they built from source you can't really get better security. "Javascript Cryptography Considered Harmful" is old FUD. It was barely coherent when first published and the only legitimate arguments it had have been fixed.
    - deleted 9y ago
      [deleted]
    - webmaven 9y ago
      > Unless you expect all of your users to build your app from source on linux that they built from source You forgot to tack on "using compilers, etc., that they also built from source".

peterwwillis 9y ago

This explains it: https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2011/august/javascript-cryptography-considered-harmful/ https://www.nccgroup.trust/us/about-us/newsroom-and-events/b...

explorigin 9y ago
Please stop propagating this article. Its positions are out of date. FTA: WHAT'S HARD ABOUT DEPLOYING JAVASCRIPT OVER SSL/TLS? You can't simply send a single Javascript file over SSL/TLS. You have to send all the page contentover SSL/TLS. Otherwise, attackers will hijack the crypto code using the least-secure connection that builds the page. ---- Seriously? Serving entire websites over https is the norm these days. It appears as though the article has been added to but not updated. Current advocates should re-read the article.
- peterwwillis 9y ago
  There's like 30 different points in this article.
  - deleted 9y ago
    [deleted]
  - explorigin 9y ago
    Yes, I didn't really want to go through each point in the article. But here's a few things to consider as you read it: - The article reads like those arguments we have in our heads where we always win. - The article is from 2011 - The article says "come back in 10 years when people aren't running browsers from 2008" (we're not to 2021 yet but the majority of browsers are evergreen now) - We have SubtleCrypto now - We have SubResourceIntegrity - We have CORS and CSP The article has some valid points, but I posit that it is more harmful than helpful. We need an Mozilla-style "arewesecureyet" website instead.
    - peterwwillis 9y ago