Problem
If you use Tomcat to run Java apps such as Atlassian Confluence (the page you're looking at now), JIRA, etc, via HTTPS, you might have noticed that your app will not support any 256 bit ciphers, however it will support 40 and 56 bit ciphers. The sslscan tool confirms this, and reports:
Accepted SSLv3 128 bits DHE-RSA-AES128-SHA Accepted SSLv3 128 bits AES128-SHA Accepted SSLv3 168 bits EDH-RSA-DES-CBC3-SHA Accepted SSLv3 56 bits EDH-RSA-DES-CBC-SHA Accepted SSLv3 40 bits EXP-EDH-RSA-DES-CBC-SHA Accepted SSLv3 168 bits DES-CBC3-SHA Accepted SSLv3 56 bits DES-CBC-SHA Accepted SSLv3 40 bits EXP-DES-CBC-SHA Accepted SSLv3 128 bits RC4-SHA Accepted SSLv3 128 bits RC4-MD5 Accepted SSLv3 40 bits EXP-RC4-MD5 Accepted TLSv1 128 bits DHE-RSA-AES128-SHA Accepted TLSv1 128 bits AES128-SHA Accepted TLSv1 168 bits EDH-RSA-DES-CBC3-SHA Accepted TLSv1 56 bits EDH-RSA-DES-CBC-SHA Accepted TLSv1 40 bits EXP-EDH-RSA-DES-CBC-SHA Accepted TLSv1 168 bits DES-CBC3-SHA Accepted TLSv1 56 bits DES-CBC-SHA Accepted TLSv1 40 bits EXP-DES-CBC-SHA Accepted TLSv1 128 bits RC4-SHA Accepted TLSv1 128 bits RC4-MD5 Accepted TLSv1 40 bits EXP-RC4-MD5
What is the problem here?
The issue here lies in the so-called policy files of JDK6. According to Sun:
Due to import control restrictions for some countries, the Java Cryptography Extension (JCE) policy files shipped with the Java SE Development Kit and the Java SE Runtime Environment allow strong but limited cryptography to be used.
Enable 256 bit ciphers
From the Sun website, download the JCE Unlimited Strength Jurisdiction Policy Files 6 Release Candidate.
Unpack the ZIP file - it will contain two jar files: local_policy.jar and US_export_policy.jar.
On our Ubuntu boxes we use the packages sun-java6-jdk, sun-java6-bin, and sun-java6-jre. The files in question are stored in /usr/lib/jvm/java-6-sun/jre/lib/security. Replace the default jar files with the ones you downloaded, then restart your app. It should now support 256 bit ciphers:
Accepted SSLv3 256 bits DHE-RSA-AES256-SHA Accepted SSLv3 256 bits AES256-SHA Accepted TLSv1 256 bits DHE-RSA-AES256-SHA Accepted TLSv1 256 bits AES256-SHA
Disable 40 and 56 bit ciphers
By default, also 40 and 56 bit ciphers are supported - you probably want to disable these. To do so you have to explicitly configure the allowed ciphers: take the previous list, include the 256 bit ciphers, leave out the 40 and 56 bit ones, then put the official names (not the OpenSSL equivalent) of the remaining ciphers in your HTTPS config (in my case at the bottom of server.xml). This will look like this:
<Connector
port="443" maxHttpHeaderSize="8192"
maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
enableLookups="false" disableUploadTimeout="true"
acceptCount="100" scheme="https" secure="true"
clientAuth="false" sslProtocol="TLS" useBodyEncodingForURI="true"
URIEncoding="UTF-8" SSLEnabled="true"
keystoreFile="/etc/ssl/private/tracker.jks"
keystorePass="hackme"
ciphers="SSL_DHE_RSA_WITH_AES_256_CBC_SHA,SSL_RSA_WITH_AES_256_CBC_SHA,
SSL_DHE_RSA_WITH_AES_128_CBC_SHA,SSL_RSA_WITH_AES_128_CBC_SHA,
SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA,SSL_RSA_WITH_3DES_EDE_CBC_SHA,
SSL_RSA_WITH_RC4_128_SHA,SSL_RSA_WITH_RC4_128_MD5,
TLS_DHE_RSA_WITH_AES_256_CBC_SHA,TLS_RSA_WITH_AES_256_CBC_SHA,
TLS_DHE_RSA_WITH_AES_128_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA,
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,TLS_RSA_WITH_3DES_EDE_CBC_SHA,
TLS_RSA_WITH_RC4_128_SHA,TLS_RSA_WITH_RC4_128_MD5" />
After restarting your app, you can verify with sslscan that now 256 bit ciphers are supported and preferred, and no 40 and 56 bits ones are available anymore:
./sslscan --no-failed my.site.org:443
[...]
Supported Server Cipher(s):
Accepted SSLv3 256 bits DHE-RSA-AES256-SHA
Accepted SSLv3 256 bits AES256-SHA
Accepted SSLv3 128 bits DHE-RSA-AES128-SHA
Accepted SSLv3 128 bits AES128-SHA
Accepted SSLv3 168 bits EDH-RSA-DES-CBC3-SHA
Accepted SSLv3 168 bits DES-CBC3-SHA
Accepted SSLv3 128 bits RC4-SHA
Accepted SSLv3 128 bits RC4-MD5
Accepted TLSv1 256 bits DHE-RSA-AES256-SHA
Accepted TLSv1 256 bits AES256-SHA
Accepted TLSv1 128 bits DHE-RSA-AES128-SHA
Accepted TLSv1 128 bits AES128-SHA
Accepted TLSv1 168 bits EDH-RSA-DES-CBC3-SHA
Accepted TLSv1 168 bits DES-CBC3-SHA
Accepted TLSv1 128 bits RC4-SHA
Accepted TLSv1 128 bits RC4-MD5
Prefered Server Cipher(s):
SSLv3 256 bits DHE-RSA-AES256-SHA
TLSv1 256 bits DHE-RSA-AES256-SHA
For apache the following will have the same result:
SSLCipherSuite ALL:!ADH:!EXP:!DES:RC4+RSA:+HIGH:+MEDIUM!SSLv2