coolchart.mscgen

# Alice & Bob classics: public key encryption
msc {
  hscale="1.4",
  wordwraparcs="true";

  Alice [linecolor="#00A1DE", textcolor="white", textbgcolor="#00A1DE", arclinecolor="#00A1DE", arctextcolor="white"],
  Bob [linecolor="#00A1DE", textcolor="white", textbgcolor="#00A1DE", arclinecolor="#00A1DE", arctextcolor="white"],
  notes [label=" ", linecolor="transparent"];

  Alice => Alice [label="sign message with own private key", linecolor="#005B82", textcolor="#005B82"];
  Alice => Bob [label="signed message", linecolor="#005B82", textcolor="#005B82"],
  notes note notes [label="This is just a sample chart with a (high level) illustration of public key encryption.", linecolor="white", textcolor="white", textbgcolor="#E77B2F"];
  Bob => Alice [label="get Alice her public key", linecolor="#005B82", textcolor="#005B82"];
  Alice >> Bob [label="Alices' public key", linecolor="#005B82", textcolor="#005B82"];
  Bob => Bob [label="verify message with Alices' public key", linecolor="#005B82", textcolor="#005B82"];
}