Using keytab file in spark standalone program - scala

Question

I am trying to access a file from HDFS in my standalone scala program using apache-spark. I get the following error upon execution.
SIMPLE authentication is not enabled. Available:[TOKEN,KERBEROS]
I found this question that explains that i need to create a keytab file and then make my standalone program use it . I have generated the keytab file . Could somebody tell me how i can use it from my program.
Any help will be greatly appreciated.
ps - I am using Hadoop 2.3.0 and spark 0.9.0
update : this is how my core-site.xml looks now :
<?xml version="1.0" encoding="UTF-8"?>
<!--Autogenerated by Cloudera Manager-->
<configuration>
<property>
<name>fs.defaultFS</name>
<value>hdfs://USHadoop</value>
</property>
<property>
<name>fs.trash.interval</name>
<value>1</value>
</property>
<property>
<name>io.compression.codecs</name>
<value>org.apache.hadoop.io.compress.DefaultCodec,org.apache.hadoop.io.compress.GzipCodec,org.apache.hadoop.io.compress.BZip2Codec,org.apache.hadoop.io.compress.DeflateCodec,org.apache.hadoop.io.compress.SnappyCodec,org.apache.hadoop.io.compress.Lz4Codec</value>
</property>
<property>
<name>hadoop.security.authentication</name>
<value>kerberos</value>
</property>
<property>
<name>hadoop.rpc.protection</name>
<value>authentication</value>
</property>
<property>
<name>hadoop.security.auth_to_local</name>
<value>DEFAULT</value>
</property>
</configuration>