target = "https://tools.ietf.org/rfc/rfc8446#2.1"

# 2.1.  Incorrect DHE Share
#
# If the client has not provided a sufficient "key_share" extension
# (e.g., it includes only DHE or ECDHE groups unacceptable to or
# unsupported by the server), the server corrects the mismatch with a
# HelloRetryRequest and the client needs to restart the handshake with
# an appropriate "key_share" extension, as shown in Figure 2.  If no
# common cryptographic parameters can be negotiated, the server MUST
# abort the handshake with an appropriate alert.
# 
#      Client                                               Server
# 
#      ClientHello
#      + key_share             -------->
#                                                HelloRetryRequest
#                              <--------               + key_share
#      ClientHello
#      + key_share             -------->
#                                                      ServerHello
#                                                      + key_share
#                                            {EncryptedExtensions}
#                                            {CertificateRequest*}
#                                                   {Certificate*}
#                                             {CertificateVerify*}
#                                                       {Finished}
#                              <--------       [Application Data*]
#      {Certificate*}
#      {CertificateVerify*}
#      {Finished}              -------->
#      [Application Data]      <------->        [Application Data]
# 
#           Figure 2: Message Flow for a Full Handshake with
#                         Mismatched Parameters
# 
# Note: The handshake transcript incorporates the initial
# ClientHello/HelloRetryRequest exchange; it is not reset with the
# new ClientHello.
# 
# TLS also allows several optimized variants of the basic handshake, as
# described in the following sections.

[[spec]]
level = "MUST"
quote = '''
If no
common cryptographic parameters can be negotiated, the server MUST
abort the handshake with an appropriate alert.
'''