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To be clear Apple's OpenSSL (currently 0.9.8zg) supports SHA2 despite its deprecated status. You can't link against it in El Capitan any more since they stopped

To be clear Apple's OpenSSL (currently 0.9.8zg) supports SHA2 despite its deprecated status. You can't link against it in El Capitan any more since they stopped shipping the development headers, but getting an OpenSSL that doesn't support SHA2 is actually somewhat challenging (You'd either need an OpenSSL compiled with OPENSSL_NO_SHA or OPENSSL_NO_SHA256 or one that predates 0.9.7h). None of that excuses Apple not checking this of course. Security.framework can do all this validation -- did they not historically provide code samples on how to do this without linking an external library?

mikeash 11y ago
Sorry, I didn't mean to imply that their ancient OpenSSL doesn't do SHA-2, although I had no idea either way. They just say you can't use it because it's deprecated, and therefore off limits to App Store apps. Historically, I believe the code samples were more or like the ones in the link I posted. I don't believe they ever posted anything that showed how to use Security.framework for the heavy lifting. I think they wanted to get everybody to bring their own code to make it so you couldn't pirate every app with a patch to one shared library.
- yuhong 11y ago
  App Store was introduced with Snow Leopard, when it was not depreciated.
Natsu 11y ago
Interesting, they use a version of OpenSSL that will go EOS at the end of the year? [1] It wouldn't support TLS 1.1 or 1.2, either, unless they've hacked that into their version. [1] https://www.openssl.org/policies/releasestrat.html https://www.openssl.org/policies/releasestrat.html
- mikeash 11y ago
  It's not used, exactly. It's more of a historical accident. Way back when, Apple shipped OpenSSL libraries as part of the OS and included them in the SDK. Naturally, some apps were built that used them. Then Apple discovered that they couldn't really upgrade the OpenSSL they shipped with the OS, because OpenSSL doesn't maintain binary compatibility. They could ship a new version, but they were stuck shipping the old version as well, and the new version would suffer the same fate. So instead, they reimplemented what they saw as the important functionality, shipped that as CommonCrypto and Security.framework, and deprecated OpenSSL to try to get people to stop using it. But they still ship it with the OS, because they don't want to break whatever apps do still use it. And they can't upgrade it, because that would defeat the whole purpose of shipping it.
  - yuhong 11y ago
    Even today Mac OS X still ships with a copy of OpenSSL 0.9.7 for that reason. I wonder when exactly it was last updated.
    - reaperhulk 11y ago
      No, it does not ship with 0.9.7. It ships with 0.9.8zg, the absolute latest in the 0.9.8 series. It is unfortunate that 0.9.8 is shipping at all (as it has numerous issues), but Apple has removed the development headers in El Capitan so nothing "new" can link against it now (although apps compiled against it on 10.10 and earlier can still use it). It will be interesting to see what Apple does when 0.9.8 is officially EOL at the end of this year. They may choose to backport fixes (if necessary) or they may just ignore it until 10.12 comes out and they decide to fully remove it.
      - yuhong 11y ago
        I am talking about the multiple versions shipped for compatibility with old apps. It is not easy to access, but look for /usr/lib/libssl.0.9.7.dylib I think. I think it is used for apps compiled using Leopard or older SDKs, which I hope no App Store apps are using, but... BTW, back in the PowerPC days they even used to ship with the even older 0.9.6 (only got rid of it when Rosetta was killed).
        reaperhulk 11y ago
        Ah, yes, those are indeed shipped for ABI compatibility with old apps. Chances are that was last updated the last time 0.9.7 got a release, which would be Feb 2007 I believe (0.9.7m).
        yuhong 11y ago
        I think Apple later patched it to for example disable renegotiation I think.

mikeash 11y ago

Sorry, I didn't mean to imply that their ancient OpenSSL doesn't do SHA-2, although I had no idea either way. They just say you can't use it because it's deprecated, and therefore off limits to App Store apps. Historically, I believe the code samples were more or like the ones in the link I posted. I don't believe they ever posted anything that showed how to use Security.framework for the heavy lifting. I think they wanted to get everybody to bring their own code to make it so you couldn't pirate every app with a patch to one shared library.

yuhong 11y ago
App Store was introduced with Snow Leopard, when it was not depreciated.

Natsu 11y ago

Interesting, they use a version of OpenSSL that will go EOS at the end of the year? [1] It wouldn't support TLS 1.1 or 1.2, either, unless they've hacked that into their version. [1] https://www.openssl.org/policies/releasestrat.html https://www.openssl.org/policies/releasestrat.html

mikeash 11y ago
It's not used, exactly. It's more of a historical accident. Way back when, Apple shipped OpenSSL libraries as part of the OS and included them in the SDK. Naturally, some apps were built that used them. Then Apple discovered that they couldn't really upgrade the OpenSSL they shipped with the OS, because OpenSSL doesn't maintain binary compatibility. They could ship a new version, but they were stuck shipping the old version as well, and the new version would suffer the same fate. So instead, they reimplemented what they saw as the important functionality, shipped that as CommonCrypto and Security.framework, and deprecated OpenSSL to try to get people to stop using it. But they still ship it with the OS, because they don't want to break whatever apps do still use it. And they can't upgrade it, because that would defeat the whole purpose of shipping it.
- yuhong 11y ago
  Even today Mac OS X still ships with a copy of OpenSSL 0.9.7 for that reason. I wonder when exactly it was last updated.
  - reaperhulk 11y ago
    No, it does not ship with 0.9.7. It ships with 0.9.8zg, the absolute latest in the 0.9.8 series. It is unfortunate that 0.9.8 is shipping at all (as it has numerous issues), but Apple has removed the development headers in El Capitan so nothing "new" can link against it now (although apps compiled against it on 10.10 and earlier can still use it). It will be interesting to see what Apple does when 0.9.8 is officially EOL at the end of this year. They may choose to backport fixes (if necessary) or they may just ignore it until 10.12 comes out and they decide to fully remove it.
    - yuhong 11y ago
      I am talking about the multiple versions shipped for compatibility with old apps. It is not easy to access, but look for /usr/lib/libssl.0.9.7.dylib I think. I think it is used for apps compiled using Leopard or older SDKs, which I hope no App Store apps are using, but... BTW, back in the PowerPC days they even used to ship with the even older 0.9.6 (only got rid of it when Rosetta was killed).
      - reaperhulk 11y ago
        Ah, yes, those are indeed shipped for ABI compatibility with old apps. Chances are that was last updated the last time 0.9.7 got a release, which would be Feb 2007 I believe (0.9.7m).
        yuhong 11y ago
        I think Apple later patched it to for example disable renegotiation I think.