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authorStefan Kangas <stefankangas@gmail.com>2023-10-24 17:28:51 +0200
committerStefan Kangas <stefankangas@gmail.com>2023-10-24 17:28:51 +0200
commitd2830c9f319d33f68fad4966ccf9d6b272233973 (patch)
tree00954872fb6179f0fff172b30ae0fb815c6fb3ba /etc/NEWS
parentdbcaaf375f285a42ff1a81c313a454264374cbdb (diff)
downloademacs-d2830c9f319d33f68fad4966ccf9d6b272233973.tar.gz
Make NSM warn if DH key exchange has less than 2048 bit primes
The previous default was to warn when servers supported only 1024 bit primes in Diffie-Hellman key exchanges. This highly conservative number was based on the observation that, in November 2018, no less than 12.7% of servers still only supported 1024 bit primes (less than 0.1% supported only 768 and 512 bits). Five years later, in October 2023, only 3.7 % of servers remain with only 1024 bit support. SSL Labs summarizes: "At this time, 2048 bits is the minimum expected strength." Therefore, it is reasonable to start warning users about this in Emacs 30.1, at which time even fewer servers with such poor capabilities will remain. Note that key exchanges based on 1024 bit prime number were considered broken for security purposes already in 2015 (see Logjam below). For more information: https://www.ssllabs.com/ssl-pulse/ https://en.wikipedia.org/wiki/Logjam_(computer_security) * lisp/net/nsm.el (nsm-protocol-check--dhe-prime-kx): Bump expected minimum number of prime bits to 2048.
Diffstat (limited to 'etc/NEWS')
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diff --git a/etc/NEWS b/etc/NEWS
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--- a/etc/NEWS
+++ b/etc/NEWS
@@ -68,6 +68,11 @@ disclosed in 2016, and its small 112 bit key size. Emacs now warns
about its use also when 'network-security-level' is set to 'medium'
(the default). See 'network-security-protocol-checks'.
+** The Network Security Manager now warns about <2048 bits in DH key exchange.
+Emacs used to warn for Diffie-Hellman key exchanges with prime numbers
+smaller than 1024 bits. Since more servers now support it, this
+number has been bumped to 2048 bits.
+
** Help
*** 'describe-function' shows function inferred type when available.