Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

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Deltavista_1797's avatar
Deltavista_1797
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Dec 10, 2014

DHE key exchange: why is ephemeral key only 1024bit long?

Hello,   during a recent analysis comparing security options provided by Apache httpd and F5 LTM we discovered that while Apache for RHEL/CentOS has lifted a limitation of 1024 bits for ephemeral ...
application delivery
LTM
security
Joe_M's avatar
Joe_M
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Mar 10, 2015

Not using DHE is what I will have to do if there isn't a way to specify 2048 or 4096 DH keys (like the example of the Linux box above). What we will lose (or in our case not get because we are upgrading from 10.2.4 and 11.3.0) is "Forward Secrecy" for slightly older clients that don't support ECDHE. They will have to rely on AES. And for the documentation about 1024 bit keys going from good to weak, that is located here on page 6 and the change record on page 8.

 

https://www.ssllabs.com/downloads/SSL_Server_Rating_Guide.pdf