#TLSLog

TLSLog is a Golang library used to debug SSL application data for Wireshark.

If ECDHE is used in Key-Exchange, Wireshark cannot decrypt the application data only by set the server private key. But Wireshark supports NSS key log format that store all information needed in application data decryption process.

NSS key log format is supported by Chrome and Firefox but not Golang. When using Golang crypto/tls library, it's difficult to debug encrypted data sent and received by SSL.

But Golang crypto/tls library does store these information internally. Thus, TLSLog hooks config.Rand and uses reflection to get master secret from crypto/tls library.

CAUTION：Only client side function is implemented, which means that TLSLog can not be used to build a SSL server.

go get github.com/123hurray/tlslog/tlslog.go

Dial is the most commonly way to build an SSL client.

config := tls.Config{InsecureSkipVerify: true}

// Get a TLSLog
tlsLog, err := NewTLSLog("log.txt")
if err != nil {
	fmt.Println("Unable to create TlsLog:", err.Error())
}

// Use TLSLog.Dial instead of tls.Dial
conn, err := tlsLog.Dial("tcp", "127.0.0.1:32123", &config)

// conn is tls.Conn, just used as is documented in tls library

Client is another way to build an SSL client.

config := tls.Config{InsecureSkipVerify: true}
tlsLog, err := NewTLSLog("log.txt")
// Make net.conn
c, s := net.Pipe()
// use TLSLog.Client instead of tls.Client
logCli := tlsLog.Client(c, &config)
// Do handshake
conn, err = logCli.Handshake()
// conn is tls.Conn, just used as is documented in tls library

See the articles below:

• Wireshark WIKI:Using the (Pre)-Master-Secret
• Decrypting TLS Browser Traffic With Wireshark – The Easy Way!

• Server side key log