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SChannel: Support SCH_USE_STRONG_CRYPTO#6734

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SChannel: Support SCH_USE_STRONG_CRYPTO#6734
xim wants to merge 4 commits intocurl:masterfrom
xim:master

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@xim
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@xim xim commented Mar 12, 2021

Feature was discussed on curl-library@cool.haxx.se; Subject: Adding flags to SChannel cred.

I wasn't sure about where, and to what extent, this should be documented.

Also note that I tested this by compiling curl.exe on the latest preview on windows 10. Downloading https://clienttest.ssllabs.com:8443/ssltest/viewMyClient.html with and without --ciphers USE_STRONG_CRYPTO and diffing the results shows that 3des is correctly disabled.

alg = get_alg_id_by_name(startCur);
if(alg)
algIds[algCount++] = alg;
#ifdef SCH_USE_STRONG_CRYPTO
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Checks revealed that old toolchains don't provide SCH_USE_STRONG_CRYPTO. Is it better to do this, or should I rather do

#ifndef SCH_USE_STRONG_CRYPTO
#define SCH_USE_STRONG_CRYPTO             0x00400000
#endif

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should I rather do

#ifndef SCH_USE_STRONG_CRYPTO
#define SCH_USE_STRONG_CRYPTO             0x00400000
#endif

yes

@bagder bagder added feature-window A merge of this requires an open feature window TLS labels Mar 14, 2021
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xim commented Mar 22, 2021

I'm happy with the patch as is, and all test failures appeared to be unrelated. Just tell me if further actions are required.

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jay commented Mar 22, 2021

It looks fine, it will be added next feature window. Ignore the test failures that's an unrelated issue.

@jay jay closed this in 67d3afa Apr 22, 2021
@jay jay removed the feature-window A merge of this requires an open feature window label Apr 22, 2021
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jay commented Apr 22, 2021

Thanks. I just landed a slightly modified version, it documents SCH_USE_STRONG_CRYPTO instead of USE_STRONG_CRYPTO but both are accepted. I did this for consistency because the other schannel cipher options use OS symbols, eg CALG_ECDH_EPHEM.

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3 participants