1. A computer-executed method for controlling the spread of interests and content in a content centric network, comprising: receiving a packet including a piece of content or an interest for the content, wherein the packet further includes a hierarchically structured name of the content; identifying, using a longest-matching lookup of the hierarchically structured name of the content, a routing policy applicable to a longest matching prefix of the hierarchically structured name, wherein the routing policy specifies a condition associated with an originating entity or a destination entity of the packet, and a forwarding action corresponding to the condition; in response to determining that the prefix matches the hierarchically structured name of the content and that the originating entity or the destination entity of the packet satisfies the condition in the routing policy, forwarding the packet according to the forwarding action specified in the routing policy; in response to determining that the originating entity or the destination entity of the packet does not satisfy the condition in the routing policy, forwarding the packet according to a default forwarding action; and defeating a denial-of-service attack against a policy enforcement system by greylisting a public key held by a signer of the content so that automatic retrieval of the public key is deferred.