```ruby
class Silverlight < Cask
  url 'http://silverlight.dlservice.microsoft.com/download/6/B/8/6B885B0B-73D4-4BCE-BFFF-154B4A402D22/20913.00/Silverlight.dmg'
  homepage 'http://www.microsoft.com/silverlight/'
  version '5.1.20913.0'
  sha1 '87181a49ec802e8eaa00bdd0b8e7dbb8c9201812'
  install 'Silverlight.pkg'
end
```

Update Silverlight Cask to use SHA256
user
```ruby
class Silverlight < Cask
  url 'http://silverlight.dlservice.microsoft.com/download/6/B/8/6B885B0B-73D4-4BCE-BFFF-154B4A402D22/20913.00/Silverlight.dmg'
  homepage 'http://www.microsoft.com/silverlight/'
  version '5.1.20913.0'
  sha256 'f3e9e1bf30adbeb891ce44595541acba7d35b23c03f96a2b7df91b15325bf4cf'
  install 'Silverlight.pkg'
end
```
assistant