Currently most of the documentation on REST exists in the Apache HBase Wiki on REST (The REST gateway used to be called 'Stargate'). There are also a nice set of blogs on How-to: Use the Apache HBase REST Interface by Jesse Anderson.
To run your REST server under SSL, set hbase.rest.ssl.enabled to true and also set the following configs when you launch the REST server:(See example commands in Section 22.214.171.124, “JMX”)
hbase.rest.ssl.keystore.store hbase.rest.ssl.keystore.password hbase.rest.ssl.keystore.keypassword
HBase ships a simple REST client, see REST client package for details. To enable SSL support for it, please also import your certificate into local java cacerts keystore:
keytool -import -trustcacerts -file /home/user/restserver.cert -keystore $JAVA_HOME/jre/lib/security/cacerts