pkey/ec: add support for octet string encoding of EC pointky/pkey-ec-point-octet-string

Add a new method named PKey::EC#to_octet_string that returns the octet
string representation of the curve point. PKey::EC::Point#to_bn, which
have already existed and is similar except that an instance of
OpenSSL::BN is returned, is rewritten in Ruby.

PKey::EC::Point#initialize now takes String as the second argument in
the PKey::EC::Point.new(group, encoded_point) form.

Also, update the tests to use #to_octet_string instead of #to_bn for
better readability.

1 files changed, 23 insertions, 1 deletions

diff --git a/lib/openssl/pkey.rb b/lib/openssl/pkey.rb
index dcedd849..8a547c34 100644
--- a/lib/openssl/pkey.rb
+++ b/lib/openssl/pkey.rb
@@ -1,3 +1,25 @@
 # frozen_string_literal: false
-module OpenSSL
+#--
+# Ruby/OpenSSL Project
+# Copyright (C) 2017 Ruby/OpenSSL Project Authors
+#++
+
+module OpenSSL::PKey
+  if defined?(EC)
+  class EC::Point
+    # :call-seq:
+    #    point.to_bn([conversion_form]) -> OpenSSL::BN
+    #
+    # Returns the octet string representation of the EC point as an instance of
+    # OpenSSL::BN.
+    #
+    # If _conversion_form_ is not given, the _point_conversion_form_ attribute
+    # set to the group is used.
+    #
+    # See #to_octet_string for more information.
+    def to_bn(conversion_form = group.point_conversion_form)
+      OpenSSL::BN.new(to_octet_string(conversion_form), 2)
+    end
+  end
+  end
 end