anchor.diff:                  {undefined, undefined}
           end,
       HelloExtensions#{ec_point_formats => EcPointFormats,
  -                     elliptic_curves => EllipticCurves}.
  +                     elliptic_curves => EllipticCurves,
  +                     signature_algs => available_signature_algs(SupportedHashSigns, Version)}.
   
   
   maybe_add_tls13_extensions({3,4},
  
positive.code:     HelloExtensions#{key_share => #key_share_client_hello{
                                       client_shares = ClientShares}}.
  
  
  signature_algs_cert(undefined) ->
      undefined;
  
negative.code:     maybe_add_tls13_extensions(Version, HelloExtensions1, SslOpts, KeyShare).
  
  
  add_tls12_extensions(_Version,
                       SslOpts,
                       ConnectionStates,
                       Renegotiation) ->
      SRP = srp_user(SslOpts),
      #{renegotiation_info => renegotiation_info(tls_record, client,
                                                 ConnectionStates, Renegotiation),
        srp => SRP,
        alpn => encode_alpn(SslOpts#ssl_options.alpn_advertised_protocols, Renegotiation),
        next_protocol_negotiation =>
            encode_client_protocol_negotiation(SslOpts#ssl_options.next_protocol_selector,
  