class Net::SSH::Transport::HMAC::Abstract

def digest(data)
  OpenSSL::HMAC.digest(digest_class.new, key, data)[0,mac_length]
end

def digest_class(*v)
  @digest_class = nil if !defined?(@digest_class)
  if v.empty?
    @digest_class = superclass.digest_class if @digest_class.nil? && superclass.respond_to?(:digest_class)
    return @digest_class
  elsif v.length == 1
    @digest_class = v.first
  else
    raise ArgumentError, "wrong number of arguments (#{v.length} for 1)"
  end
end

def digest_class
  self.class.digest_class
end

def initialize(key=nil)
  self.key = key
end

def key=(value)
  @key = value ? value.to_s[0,key_length] : nil
end

def key_length(*v)
  @key_length = nil if !defined?(@key_length)
  if v.empty?
    @key_length = superclass.key_length if @key_length.nil? && superclass.respond_to?(:key_length)
    return @key_length
  elsif v.length == 1
    @key_length = v.first
  else
    raise ArgumentError, "wrong number of arguments (#{v.length} for 1)"
  end
end

def key_length
  self.class.key_length
end

def mac_length(*v)
  @mac_length = nil if !defined?(@mac_length)
  if v.empty?
    @mac_length = superclass.mac_length if @mac_length.nil? && superclass.respond_to?(:mac_length)
    return @mac_length
  elsif v.length == 1
    @mac_length = v.first
  else
    raise ArgumentError, "wrong number of arguments (#{v.length} for 1)"
  end
end

def mac_length
  self.class.mac_length
end