Is there a way to make `GrpcClient`s use TLS 1.3 o...

# kotlinx-rpc

[mannodermaus]

Is there a way to make `GrpcClient`s use TLS 1.3 only? Our backend does not talk 1.2, so the client's connection attempt is rejected.

[mannodermaus]

Example stacktrace:

Caused by: javax.net.ssl.SSLProtocolException: Read error: ssl=0xb4000074f8c3aa98: Failure in SSL library, usually a protocol error
error:1000042e:SSL routines:OPENSSL_internal:TLSV1_ALERT_PROTOCOL_VERSION (/usr/local/google/home/prb/src/boringssl/ssl/tls_record.cc:594 0xb400007478c66dd8:0x00000001)
	at org.conscrypt.NativeCrypto.ENGINE_SSL_read_direct(Native Method)
	at org.conscrypt.NativeSsl.readDirectByteBuffer(NativeSsl.java:567)
	at org.conscrypt.ConscryptEngine.readPlaintextDataDirect(ConscryptEngine.java:1099)
	at org.conscrypt.ConscryptEngine.readPlaintextData(ConscryptEngine.java:1083)
	at org.conscrypt.ConscryptEngine.unwrap(ConscryptEngine.java:880)
	... 26 more

[Alexander Sysoev]

Is this jvm or native? Or android?

[Alexander Sysoev]

In principle it can, though I need to check how to configure it

[mannodermaus]

The target is an Android application

[Alexander Sysoev]

Hey!
Will this work for you? -Djdk.tls.client.protocols="TLSv1.3"

https://www.java.com/en/configure_crypto.html

[Alexander Sysoev]

gRPC should pick this up

[mannodermaus]

It's looking promising! I can confirm that the server starts responding with data after setting this in my application's onCreate via System.setProperty! Thank you very much