Invalid signature exception

Aws::DynamoDB::Errors::InvalidSignatureException: The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.

The Canonical String for this request should have been
'POST
/

content-type:application/x-amz-json-1.0
host:dynamodb.us-east-1.amazonaws.com
user-agent:aws-sdk-ruby2/2.0.0.rc6 rbx/2.1.0 x86_64-linux-gnu Seahorse/0.1.0
x-amz-content-sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a
x-amz-date:20140219T141420Z
x-amz-target:DynamoDB_20120810.ListTables

content-type;host;user-agent;x-amz-content-sha256;x-amz-date;x-amz-target
44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a'

The String-to-Sign should have been
'AWS4-HMAC-SHA256
20140219T141420Z
20140219/us-east-1/dynamodb/aws4_request
e0a6971e24e22b3dbb52b5c9708be3ae0437f9a7f4a22660e733e03562c42600'

        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/gems/aws-sdk-core-2.0.0.rc6/vendor/seahorse/lib/seahorse/client/plugins/raise_response_errors.rb:15:in `call'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/gems/aws-sdk-core-2.0.0.rc6/vendor/seahorse/lib/seahorse/client/plugins/param_conversion.rb:22:in `call'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/gems/aws-sdk-core-2.0.0.rc6/vendor/seahorse/lib/seahorse/client/request.rb:70:in `send_request'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/gems/aws-sdk-core-2.0.0.rc6/vendor/seahorse/lib/seahorse/client/plugins/operation_methods.rb:42:in `add_operation_helpers'
        test.rb:17:in `doit'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/calls.rb:26:in `dispatch'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/calls.rb:63:in `dispatch'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/cell.rb:60:in `invoke'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/cell.rb:71:in `task'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/actor.rb:362:in `task'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/tasks.rb:55:in `initialize'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/tasks/task_fiber.rb:15:in `create'
        kernel/bootstrap/proc.rb:20:in `call'
        (celluloid):0:in `remote procedure call'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/calls.rb:92:in `value'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/proxies/sync_proxy.rb:33:in `method_missing'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/proxies/cell_proxy.rb:17:in `_send_'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/pool_manager.rb:41:in `_send_'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/pool_manager.rb:123:in `doit'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/calls.rb:26:in `dispatch'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/calls.rb:122:in `dispatch'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/cell.rb:60:in `invoke'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/cell.rb:0:in `task'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/actor.rb:0:in `task'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/tasks.rb:55:in `initialize'
        /home/myitcv/.rbenv/versions/rbx-2.2.5/gems/bundler/gems/celluloid-def3baf4b83f/lib/celluloid/tasks/task_fiber.rb:15:in `create'