How to decrypt TLS Packets using PyShark?

[jeyabharathi12]

I am able to decrypt TLS packets using wireshark as I have master key, but I want to know how to do using PyShark. How to decrypt TLS Packets using PyShark?

[mythly]

Has same problem.
If it's not supported, is there any other programmable way to get decrypted plain text from TLS packets?

[DCMMC]

Please refer to argument override_prefs of FileCapture.
e.g.

import os
import pyshark
cap = pyshark.FileCapture(
    'google.pcap', use_json=True, include_raw=True,
    override_prefs={'ssl.keylog_file': os.path.abspath('sslkeys_google.log')},
    debug=True)

[skumar7777]

Please refer to argument override_prefs of FileCapture.
e.g.

import os
import pyshark
cap = pyshark.FileCapture(
    'google.pcap', use_json=True, include_raw=True,
    override_prefs={'ssl.keylog_file': os.path.abspath('sslkeys_google.log')},
    debug=True)

Can you please help with accessing the decrypted data?

I am able to see the decrypted data in wireshark but not able to figure out how to see the decrypted data using pyshark, not sure if pyshark even decrypts it.

When I pretty print the packet, it shows the Encrypted Application Data as under.

Layer TLS:
TLSv1.2 Record Layer: Application Data Protocol: http-over-tls
Content Type: Application Data (23)
Version: TLS 1.2 (0x0303)
Length: 51
Encrypted Application Data: 19710...................................

I am using LiveCapture.

[August1328]

I had the same problem and I found a solution for decrpyting the TLS connections, so I hope this helps (I am not a python pro...)

I was able to see the decrpyted TLS traffic in Wireshark and after unsuccessfully trying to access it with pyshark I suddenly realized there are 2 new layers in Wireshark: Websocket and DATA-TEXT-LINES.

So I tried to access those two like the other layers and this finally worked: I was able to print the decrypted app data using the DATA-TEXT-LINES layer.

This is the code, that works for me:

import pyshark
import os

capture = pyshark.FileCapture('C:/Users/xxxxxxx/py_gfua/files/26042021.pcapng',
                                display_filter='ip.src == xxx.xxx.xxx.xx',
                                override_prefs={'tls.keylog_file': os.path.abspath('./py_gfua/tlskey.log')},
                                debug=True)

for packet in capture:

    if "DATA-TEXT-LINES" in packet:

        #print(packet.layers)
        print(packet['DATA-TEXT-LINES'])

    else:
        print("whatever, not decrypted data")

2 hints:

• on my OS (Win10), there is no error or warning if the tlskey file does not exist, you misspelled the file name or the path is incorrect! That is why I set debugging = true, please check thoroughly
• please note the commented line "#print(packet.layers)". I left it in for you to see if your decryption works: My encrypted traffic had 4 layers: ETH Layer, IP Layer, TCP Layer, TLS Layer. After decryption there are 6 layers: ETH Layer, IP Layer, TCP Layer, TLS Layer, WEBSOCKET Layer, DATA-TEXT-LINES Layer

The decrypted data is printed like this:

Layer DATA-TEXT-LINES:
[truncated][{"xxxxxxxxxxxxxxxxxxxxxxxx....

Now to my question or problem: The data is 'truncated' because it is limited to 256 characters. Unfortunately my encrypted data is longer, appr. 1000 characters.

Does someone have a solution to print or access the whole data? It works in Wireshark but I´m stuck at getting it working using pyshark?

[eltonrosa]

@August1328 I've got the same issue. Have you find a way around? It is strange enough that the data downloaded doesn't come truncated already. In Wireshark it is quite straightforward to decompress them and avoid truncated losses.

[August1328]

@eltonrosa I read a little further into the Wireshark documentation, but I did not solve this resp. I did not put too much effort into this since using the decrpyted data was not 100% legal...

Anyways, I remember that I found out there is a max character limit and one should try to change this value in the program code and then recompile it - that´s where I stopped. But I still got the link, hope this helps:

https://osqa-ask.wireshark.org/questions/62019/packet-data-being-truncated-in-columns/

[chribro88]

Does someone have a solution to print or access the whole data? It works in Wireshark but I´m stuck at getting it working using pyshark?

If you're using a proxy (and its a HTTPS request) then they will be two HTTP layers.

for packet in capture.sniff_continuously():
    http_layers = packet.get_multiple_layers('http')
    for http_layer in http_layers[::-1]:
        if http_layer.has_field('file_data'):
          print(http_layer.file_data)
          break