Hiya,
On 31/08/2023 15:00, Filip Petr. wrote:
My goal is for a community of automation experts to have a perfectly matched Client hello (JA3 hash) fingerprint as modern commercial browsers so they can do their job more successfully. For this to happen one must add 8 additional extensions to the Client hello request.
Can't help with your query, sorry, but worth noting that work on encrypted client hello (ECH) is progressing towards completion in the IETF, and a pre-standards version is deployed now in browsers (albeit behind a flag for both FF and chromium-derived browsers). If, as I'd hope, ECH gets finalised early next year and then deployed, that'll change the profile of the ClientHello possibly significantly. As this is something on which I'm working [1] I'd be happy to discuss how to get ECH support working, then deployed, in this context too, so if that's of interest, just ping me. Cheers, S. [1] https://defo.ie
Those changes were
done under /sun/security/ssl. Mostly modifying SSLExtension.java file by
adding additional extensions. My goal is to have perfectly working adjusted
extensions and to use TLS1.3 on top of that. The extensions that my Java
client using standard Java net library had prior me adding new ones were:
1.key_share
2. signature_algorithms_cert
3. psk_key_exchange_modes
4. supported_versions
5. signature_algorithms
6. application_layer_protocol_negotiation
7. supported_group
8. status_request
9. server_name
After the change to match Chrome's extensions it became:
1. TLS_GREASE (0x5a5a)
2. status_request
3. ec_point_formats
4. supported_groups
5. signed_certificate_timestamp
6. application_settings
7. server_name
8. application_layer_protocol_negotiation
9. key_share
10. extended_master_secret
11. extensionRenegotiationInfo
12. session_ticket
13. supported_versions
14. signature_algorithms
15. psk_key_exchange_modes
16. TLS_GREASE (0x3a3a)
17. padding
The reason for me making this post is because when I
add application_settings extension, the module doesn't work for certain
websites such as for google domains and for some it works perfectly fine. I
analysed in Wireshark the requests they were all properly done but for some
weird reason, Java gives back following exceptions once I encounter some
sites it crashes on
1. Received fatal alert: decode_error
2. Unknown handshake type size, Handshake.msg_type = 25
3. Received fatal alert: unexpected_message
Unfortunately I don't know how to track fatal alerts and their cores so I'm
not sure how I can handle this. Why does Java crash on this simple
extension such as application_settings? It holds nothing but following
{
"name": "application_settings (17513)",
"protocols": [
"h2"
]
}
That's pretty much it. Once I remove this extension, the module works
just fine with the rest added ones. I should add on top that i do
these 2 following lines as my ssl configuration prior creating java
client
sslParams.setApplicationProtocols(new String[] {"h2", "http/1.1"});
sslParams.setProtocols(new String[]{"TLSv1.3"});
Any help would be welcome! Thanks in advance!
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