Hi Antoan,
I faced the same problem (e.g. 'Checksum failed'), and, in my case, I solve this error by changing the 'host' security-domain configuration.
According to https://community.jboss.org/wiki/DRAFTUsingJBossNegotiationOnAS7, the 'host' security-domain should be configured like that :
<security-domain name="host" cache-type="default">
<authentication>
<login-module code="Kerberos" flag="required">
<module-option name="storeKey" value="true"/>
<module-option name="useKeyTab" value="true"/>
<module-option name="principal" value="host/testserver@MY_REALM"/>
<module-option name="keyTab" value="/home/username/service.keytab"/>
<module-option name="doNotPrompt" value="true"/>
<module-option name="debug" value="false"/>
</login-module>
</authentication>
</security-domain>
In my case, the solution was to configure it like that :
<security-domain name="host" cache-type="default">
<authentication>
<login-module code="Kerberos" flag="required">
<module-option name="storeKey" value="true"/>
<module-option name="useKeyTab" value="true"/>
<module-option name="principal" value="HTTP/{testserver}"/>
<module-option name="keyTab" value="/home/username/service.keytab"/>
<module-option name="doNotPrompt" value="true"/>
<module-option name="debug" value="false"/>
</login-module>
</authentication>
</security-domain>
where {testserver} is the FQDN of the machine.
Cheers