TLSv1.3: Downgrade Protection mechanism #3022
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kaduk
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Mar 23, 2017
ssl/statem/statem_lib.c
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| 0x44, 0x4f, 0x57, 0x4e, 0x47, 0x52, 0x44, 0x00 | ||
| }; | ||
| static const unsigned char tls12downgrade[] = { | ||
| 0x44, 0x4f, 0x57, 0x4e, 0x47, 0x52, 0x44, 0x01 |
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These are in both statem_lib and s3_lib; should they be consolidated and prototyped in ssl_locl.h?
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Could do. I actually had that at one point in development. The problem I had was you have to declare them with an explicit size if you put the declarations in a header - otherwise sizeof doesn't work. I thought the implicit size was better, and no big deal to have them declared twice. I don't have a strong opinion either way though, so I'll go with whatever the consensus is.
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declare once and count the bytes carefully :)
Make it disabled by default. When TLSv1.3 is out of draft we can remove this option and have it enabled all the time.
mattcaswell
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New commit pushed to address the feedback. Also rebased and fixed a travis issue. |
richsalz
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Mar 24, 2017
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Pushed. Thanks. |
levitte
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Mar 24, 2017
Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #3022)
levitte
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Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #3022)
levitte
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Make it disabled by default. When TLSv1.3 is out of draft we can remove this option and have it enabled all the time. Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #3022)
levitte
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Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #3022)
levitte
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Mar 24, 2017
Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from #3022)
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Description of change
This PR implements the TLSv1.3 downgrade protection mechanism.
For now it is switched off by default (enabled via "enable-tls13downgrade"). This is because the current draft says pre-RFC implementations SHOULD NOT implement it (if a pre-RFC implementation connects to an RFC implementation it will mistakenly detect a downgrade and abort the connection).
As soon as the draft becomes an RFC we can enable it by default and remove the "enable-tls13downgrade" option completely.