anchor.diff:  === Claims validation
   
   _buddy-sign_ json web encryption, like *jws*, also implements validation of a
  -concrete subset of claims: *exp* (expiration time), *nbf* (not before), *iss*
  -(issuer) and *aud* (audience).
  +concrete subset of claims: *iat* (issue time), *exp* (expiration time),
  +*nbf* (not before), *iss* (issuer) and *aud* (audience).
   
   The validation is performed on decoding the token. If `:exp` claim is found and
   is posterior to the current date time (UTC) an validation exception will be raised.
  +Alternatively, the time to validate token against can be specified as `:now`
  +option to `decrypt`.
   
   Let see an example using direct api:
   
  
positive.code: 
  [source,clojure]
  ----
  [buddy/buddy-sign "0.12.0"]
  ----
  
  And is tested under JDK7 and JDK8.
  
negative.code: = buddy-sign - High level message signing.
  Andrey Antukh, <niwi@niwi.be>
  0.13.0
  :toc: left
  :!numbered:
  :source-highlighter: pygments
  