wkd: implement basic lookup of keys through wkd

wkd is the web key directory. See the Readme.md in
  /lib/nickserver/wkd

5 files changed, 78 insertions, 0 deletions

diff --git a/lib/nickserver/email_address.rb b/lib/nickserver/email_address.rb
index c5d5df7..20f642c 100644
--- a/lib/nickserver/email_address.rb
+++ b/lib/nickserver/email_address.rb
@@ -37,6 +37,10 @@ module Nickserver
       address.split('@')[1]
     end
 
+    def local_part
+      address.split('@')[0]
+    end
+
     def to_s
       address
     end
diff --git a/lib/nickserver/wkd/Readme.md b/lib/nickserver/wkd/Readme.md
new file mode 100644
index 0000000..c93e08c
--- /dev/null
+++ b/lib/nickserver/wkd/Readme.md
@@ -0,0 +1,8 @@
+Allow querying keys from web key directories offered by the users
+provider.
+
+Summary is here:
+  https://wiki.gnupg.org/WKD
+
+Specs are here:
+  https://tools.ietf.org/html/draft-koch-openpgp-webkey-service-00
diff --git a/lib/nickserver/wkd/source.rb b/lib/nickserver/wkd/source.rb
new file mode 100644
index 0000000..01f376e
--- /dev/null
+++ b/lib/nickserver/wkd/source.rb
@@ -0,0 +1,16 @@
+require 'nickserver/source'
+require 'nickserver/response'
+
+module Nickserver
+  module Wkd
+    class Source < Nickserver::Source
+
+      def query(email)
+        url = Url.new(email)
+        status, body = adapter.get url
+        return Nickserver::Response.new(status, body)
+      end
+
+    end
+  end
+end
diff --git a/lib/nickserver/wkd/url.rb b/lib/nickserver/wkd/url.rb
new file mode 100644
index 0000000..965e7ec
--- /dev/null
+++ b/lib/nickserver/wkd/url.rb
@@ -0,0 +1,31 @@
+require 'digest/sha1'
+require 'zbase32'
+
+module Nickserver
+  module Wkd
+    class Url
+
+      def initialize(email)
+        @domain = email.domain.downcase
+        @local_part = email.local_part.downcase
+      end
+
+      def to_s
+        "https://#{domain}/.well-known/openpgpkey" +
+          "/hu/#{domain}/#{encoded_digest}"
+      end
+
+      protected
+
+      attr_reader :domain, :local_part
+
+      def encoded_digest
+        ZBase32.encode32(digest.to_i(16).to_s(2))
+      end
+
+      def digest
+        Digest::SHA1.hexdigest local_part
+      end
+    end
+  end
+end
diff --git a/lib/zbase32.rb b/lib/zbase32.rb
new file mode 100644
index 0000000..754213d
--- /dev/null
+++ b/lib/zbase32.rb
@@ -0,0 +1,19 @@
+module ZBase32
+
+  ALPHABET = 'ybndrfg8ejkmcpqxot1uwisza345h769'.split('').freeze
+
+  def self.encode32(bin_string)
+    bin_string.scan(/[01]{1,5}/).map do |bits|
+      ALPHABET[bits.ljust(5, '0').to_i(2)]
+    end.join
+  end
+
+  def self.decode32(enc)
+    bin = enc.split('').map do |char|
+      ALPHABET.index(char).to_s(2).rjust(5, '0')
+    end.join
+    bin[0, (8 * (bin.length / 8))]
+     # .sub /10*$/ ,'1'
+  end
+
+end