module GPGME::KeyCommon

def capability

+:encrypt+, +:sign+, +:certify+ or +:authenticate+
Array of capabilities for this key. It can contain any combination of
# 
def capability
  caps = []
  caps << :encrypt if @can_encrypt == 1
  caps << :sign if @can_sign == 1
  caps << :certify if @can_certify == 1
  caps << :authenticate if @can_authenticate == 1
  caps
end

def secret? 

def secret?
  @secret == 1
end

def trust

Returns one of +:revoked+, +:expired+, +:disabled+, +:invalid+
Returns nil if the trust is valid.
# 
def trust
  return :revoked if @revoked == 1
  return :expired if @expired == 1
  return :disabled if @disabled == 1
  return :invalid if @invalid == 1
end

def usable_for?(purposes)

Returns false if the keys trust has been invalidated.

is passed then will return true.
Checks if the key is capable of all of these actions. If empty array
# 
def usable_for?(purposes)
  unless purposes.kind_of? Array
    purposes = [purposes]
  end
  return false if [:revoked, :expired, :disabled, :invalid].include? trust
  return (purposes - capability).empty?
end