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Content distribution systems benefit from network coding in terms of error/loss protection and faster dissemination at the cost of exposing the data to intermediate nodes that are not the intended recipients. In these systems data secrecy is at risk and it can be guaranteed by using encryption as a straightforward method. However, this inevitably increases the communication costs and decreases the willingness to cooperate of intermediate nodes, which have no expectation of recovering the file. In this paper we propose an incentive secrecy preserving scheme based on obfuscation for time-sensitive data. The source intentionally obscures the original file and informs only the intended recipients which file blocks are corrupted. This scheme, combined with network coding, preserves the data secrecy and, in the meantime, fosters the cooperation of intermediate nodes. The evaluation of our solution shows that the proposed scheme is more efficient than encryption based secrecy preserving methods. In particular, the distribution of content in terms of downloading speed is greatly enhanced.