In the Content-Centric Networking (CCN) architecture, content confidentiality is treated as an application-layer concern. Data is only encrypted if the producer and consumer agree on a suitable access control policy and enforcement mechanism. In contrast, transport encryption in TCP/IP applications is increasingly opportunistic for better privacy. This type of encryption is woefully lacking in CCN. To that end, we present TRAPS, a protocol to enable transparent packet security and opportunistic encryption for all CCN data. TRAPS builds on the assumption that knowledge of a name gives one access to the corresponding content; otherwise, by design, the content remains encrypted and secure. TRAPS builds on recent advances in memory hard functions and message-locked encryption to protect data in transit. We show that the security of TRAPS is dependent on the distribution of content names and argue that it can be significantly improved if secure sessions are used to transmit small pieces of information from producers to consumers. Our performance assessment indicates TRAPS is capable of providing opportunistic encryption to CCN without significant throughput loss for reasonable packet throughput measurements.