Index: ext/openssl/lib/openssl/digest.rb
===================================================================
--- ext/openssl/lib/openssl/digest.rb	(revision 36588)
+++ ext/openssl/lib/openssl/digest.rb	(working copy)
@@ -68,5 +68,22 @@ module OpenSSL
     end
 
   end # Digest
+
+  # Returns a Digest subclass by +name+.
+  #
+  #   require 'openssl'
+  #
+  #   OpenSSL::Digest("MD5")
+  #   # => OpenSSL::Digest::MD5
+  #
+  #   Digest("Foo")
+  #   # => NameError: wrong constant name Foo
+
+  def Digest(name)
+    OpenSSL::Digest.const_get(name)
+  end
+
+  module_function :Digest
+
 end # OpenSSL
 
Index: test/openssl/test_digest.rb
===================================================================
--- test/openssl/test_digest.rb	(revision 36588)
+++ test/openssl/test_digest.rb	(working copy)
@@ -103,6 +103,14 @@ class OpenSSL::TestDigest < Test::Unit::
     end
   end
 
+  def test_openssl_digest
+    assert_equal OpenSSL::Digest::MD5, OpenSSL::Digest("MD5")
+
+    assert_raises NameError do
+      OpenSSL::Digest("no such digest")
+    end
+  end
+
   private
 
   def check_digest(oid)