I'm 90% sure that this is a postman config issue, but I'll give other details in case they matter.
I'm testing out Cloudflare's APIs through postman, and I'm just trying to get the list of buckets. I believe that I have the authorization correct (using AWS signature) and I believe I have the correct account-id.
The error I'm getting is:
Error: write EPROTO 4771177816:error:10000410:SSL routines:OPENSSL_internal:SSLV3_ALERT_HANDSHAKE_FAILURE:../../../../src/third_party/boringssl/src/ssl/tls_record.cc:594:SSL alert number 40 4771177816:error:1000009a:SSL routines:OPENSSL_internal:HANDSHAKE_FAILURE_ON_CLIENT_HELLO:../../../../src/third_party/boringssl/src/ssl/handshake.cc:644:
I'm not setting SSL things manually, so whatever the defaults are, I haven't found them yet.