server: decision authenticity ENABLED

  held effect                     : held_for_approval
  forged approve (no mac)         : error unauthenticated decision: bad or m
  forged approve (bad mac)        : error unauthenticated decision: bad or m
  forged reject  (bad mac)        : error unauthenticated decision: bad or m
  still held after 3 forgeries    : held_for_approval
  legitimate approve (valid mac)  : release

E-AUTH: forged decisions refused; effect held through every forgery; only the secret-holder released it -> decision channel authenticated
