curl --request POST \
  --url https://api.example.com/handshake \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <x-api-key>' \
  --data '
{
  "target_did": "<string>"
}
'

{
  "session_token": "<string>",
  "expires_at": "<string>"
}