Which version of Elasticsearch does Shield work with?

I deployed shield on ES v1.1.2 but it failed due to java.lang.NoClassDefFoundError ... is it NOT meant to be used by ES v1.1.2?

[Spot] version[1.1.2], pid[18013], build[e511f7b/2014-05-22T12:27:39Z]
[INFO ][node] [Spot] initializing ...
[WARN ][plugins] [Spot] failed to load plugin from [jar:file:/usr/share/elasticsearch/plugins/shield/elasticsearch-shield-1.1.1.jar!/es-plugin.properties]
org.elasticsearch.ElasticsearchException: Failed to load plugin class [org.elasticsearch.shield.ShieldPlugin]
    at org.elasticsearch.plugins.PluginsService.loadPlugin(PluginsService.java:512)
Caused by: java.lang.NoClassDefFoundError: org/elasticsearch/ElasticsearchException$WithRestHeaders
    ... 7 more

Shield only works with Elasticsearch 1.4.2 and newer. I would recommend upgrading to Elasticsearch 1.7.1 as it contains a lot of fixes and 1.1.2 is pretty old.