SQS input throws an exception: uninitialized constant Digest::SHA256

Starting logstash throws an uninitialized constant Digest::SHA256 exception when you have sqs defined as an input.

Config:
input {
sqs

{ access_key_id => "zzzzz" secret_access_key => "xxxxx" region => "us-west-2" queue => "ops_logstash_dev" debug => true }

}

output {
elasticsearch

{ host => "127.0.0.1" cluster => "ops_logstash_dev" }

}

Output:
Using milestone 1 input plugin 'sqs'. This plugin should work, but would benefit from use by folks like you. Please let us know if you find bugs or have suggestions on how to improve this plugin. For more information on plugin milestones, see http://logstash.net/docs/1.2.2/plugin-milestones {:level=>:warn}
Using milestone 1 codec plugin 'json'. This plugin should work, but would benefit from use by folks like you. Please let us know if you find bugs or have suggestions on how to improve this plugin. For more information on plugin milestones, see http://logstash.net/docs/1.2.2/plugin-milestones {:level=>:warn}
Registering SQS input {:queue=>"ops_logstash_dev", :level=>:info}
Unable to access SQS queue. {:error=>"uninitialized constant Digest::SHA256", :queue=>"ops_logstash_dev", :level=>:error}
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The error reported is:
uncaught throw uninitialized constant Digest::SHA256 in thread 0x7e0