[tor-bugs] #27971 [Core Tor/Tor]: Still supports 1024 bit keys
Tor Bug Tracker & Wiki
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Wed Oct 10 17:14:09 UTC 2018
#27971: Still supports 1024 bit keys
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Reporter: kroeckx | Owner: nickm
Type: defect | Status: assigned
Priority: High | Milestone: Tor: 0.3.5.x-final
Component: Core Tor/Tor | Version:
Severity: Normal | Resolution:
Keywords: crypto regression? | Actual Points:
Parent ID: | Points:
Reviewer: | Sponsor:
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Comment (by nickm):
Okay, I've investigated this a bit more.
Changing TLS_DH_PRIME to a 2048-bit prime is easy enough; after doing so,
the 0.3.5 unit tests almost pass at security level 2, and "make test-
network" passes.
In 0.2.9, increasing the TLS prime length to 2048 is also okay. However,
in 0.2.9, raising the security level to 2 makes a few dozen unit tests
fail.
Here's what I'd propose:
* Raise the TLS prime size to the 2048-bit named prime from RFC7919 in
0.2.9 and forward, fixing unit tests as needed.
* In versions before 0.3.4 or 0.3.5, move the
SSL_CTX_set_security_level(1) call to only happen in the unit tests.
* In 0.3.5, remove the SSL_CTX_set_security_level() call entirely, and
fix the one failing unit test.
(I only tested this with OpenSSL 1.1.0i -- there might well be
compatibility issues with other versions for us to sort out.)
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27971#comment:6>
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