TLS Decryption

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I have a task: Given a original pcap file, the output is, Two pcap files with the same number of packets, one original and the other all decrypted. Then each message should be corresponding one by one.

I don't konw how to do it. Can someone help me? Thanks very much.

I have already run wireshark source code by using VS, and my idea is to use it to print the plaintext(I can find it in packet-tls-utils.c) to .pcap. It's OK?