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Description of problem:
When using keys that provide 192 bit security (7680 bit RSA[1]), mod_ssl selects only 4096 bit long DHE parameters.
Version-Release number of selected component (if applicable):
httpd-2.4.6-16.el7
How reproducible:
Always
Steps to Reproduce:
SSLCRT=/etc/pki/tls/certs/localhost.crt
SSLKEY=/etc/pki/tls/private/localhost.key
openssl req -x509 -newkey rsa:7680 -keyout ${SSLKEY} -out ${SSLCRT} -subj /CN=localhost -nodes -batch
systemctl restart httpd
openssl s_client -CAfile ${SSLCRT} -cipher 'kEDH:!aNULL' -connect localhost:443
Actual results:
---
No client certificate CA names sent
Server Temp Key: DH, 4096 bits
---
SSL handshake has read 4532 bytes and written 806 bytes
---
New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-GCM-SHA384
Server public key is 8192 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
Protocol : TLSv1.2
Cipher : DHE-RSA-AES256-GCM-SHA384
Session-ID: DB8B7F0A108852065FBADD51EDBEE30AE24A669B6A8C3495E8B5733040C02EDD
Session-ID-ctx:
Master-Key: 451DFE6AB51F8B1E13E7BB09D723DFC84EE29A0D2699E61D35EDFED5A945CB27BE345466A02395EE3AC310EDB748E5C0
Key-Arg : None
Krb5 Principal: None
PSK identity: None
PSK identity hint: None
Start Time: 1394040945
Timeout : 300 (sec)
Verify return code: 0 (ok)
Expected results:
---
No client certificate CA names sent
Server Temp Key: DH, 8192 bits
---
Additional info:
While generation of DHE parameters of this size take significant amount of time, openssl 1.0.1 has well known dhe parameters up to 8192 bit so there is little reason not to use them.
This is also why this entry doesn't apply for 256 bit security level.
1 - http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57_part1_rev3_general.pdf
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHSA-2015-0325.html
Description of problem: When using keys that provide 192 bit security (7680 bit RSA[1]), mod_ssl selects only 4096 bit long DHE parameters. Version-Release number of selected component (if applicable): httpd-2.4.6-16.el7 How reproducible: Always Steps to Reproduce: SSLCRT=/etc/pki/tls/certs/localhost.crt SSLKEY=/etc/pki/tls/private/localhost.key openssl req -x509 -newkey rsa:7680 -keyout ${SSLKEY} -out ${SSLCRT} -subj /CN=localhost -nodes -batch systemctl restart httpd openssl s_client -CAfile ${SSLCRT} -cipher 'kEDH:!aNULL' -connect localhost:443 Actual results: --- No client certificate CA names sent Server Temp Key: DH, 4096 bits --- SSL handshake has read 4532 bytes and written 806 bytes --- New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-GCM-SHA384 Server public key is 8192 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE SSL-Session: Protocol : TLSv1.2 Cipher : DHE-RSA-AES256-GCM-SHA384 Session-ID: DB8B7F0A108852065FBADD51EDBEE30AE24A669B6A8C3495E8B5733040C02EDD Session-ID-ctx: Master-Key: 451DFE6AB51F8B1E13E7BB09D723DFC84EE29A0D2699E61D35EDFED5A945CB27BE345466A02395EE3AC310EDB748E5C0 Key-Arg : None Krb5 Principal: None PSK identity: None PSK identity hint: None Start Time: 1394040945 Timeout : 300 (sec) Verify return code: 0 (ok) Expected results: --- No client certificate CA names sent Server Temp Key: DH, 8192 bits --- Additional info: While generation of DHE parameters of this size take significant amount of time, openssl 1.0.1 has well known dhe parameters up to 8192 bit so there is little reason not to use them. This is also why this entry doesn't apply for 256 bit security level. 1 - http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57_part1_rev3_general.pdf