Hello, with the following commands: openssl s_server -accept 18010 -cert srv.crt -key test.key \ -CAfile testca.crt -debug -cipher 'NULL-SHA256' -dtls1_2 openssl s_client -connect localhost:18010 -cert clnt.crt \ -key test.key -CAfile testca.crt -debug \ -cipher 'COMPLEMENTOFALL:eNULL' -dtls1_2 NULL ciphers work fine with OpenSSL 1.0.2g. With OpenSSL 1.1.1g the handshake fails on the server side with 140295725053248:error:14102438:SSL routines:dtls1_read_bytes:tlsv1 \ alert internal error:../ssl/record/rec_layer_d1.c:611:SSL alert number \ 80 Even on OpenSSL 1.1.1g 'openssl ciphers -v NULL' lists NULL-SHA256. I'm only using s_server and s_client as tests, but I have the same problem in my application if I use SSL_CTX_set_cipher_list(sslCtx, "NULL-SHA256"); What can I do to get NULL ciphers for no encryption working? Detlef