diff --git a/Gemfile.lock b/Gemfile.lock
index ff8a1f6..09d753c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -14,6 +14,7 @@ GEM
       amq-protocol (>= 0.9.4)
       eventmachine
     antlr3 (1.8.12)
+    bouncy-castle-java (1.5.0146.1)
     builder (3.1.4)
     crack (0.3.1)
     cucumber (1.2.1)
@@ -23,20 +24,26 @@ GEM
       json (>= 1.4.6)
     diff-lcs (1.1.3)
     eventmachine (1.0.0)
+    eventmachine (1.0.0-java)
     gherkin (2.11.5)
       json (>= 1.4.6)
+    gherkin (2.11.5-java)
+      json (>= 1.4.6)
     hashie (1.2.0)
     highline (1.6.15)
     httparty (0.9.0)
       multi_json (~> 1.0)
       multi_xml
     i18n (0.6.1)
+    jruby-openssl (0.7.7)
+      bouncy-castle-java (>= 1.5.0146.1)
     json (1.7.5)
+    json (1.7.5-java)
     multi_json (1.3.7)
     multi_xml (0.5.1)
     nokogiri (1.5.5)
+    nokogiri (1.5.5-java)
     rake (0.9.2.2)
-    redcarpet (2.2.2)
     rspec (2.11.0)
       rspec-core (~> 2.11.0)
       rspec-expectations (~> 2.11.0)
@@ -67,6 +74,7 @@ GEM
       yard (~> 0.7)
 
 PLATFORMS
+  java
   ruby
 
 DEPENDENCIES
@@ -78,10 +86,10 @@ DEPENDENCIES
   highline
   httparty
   i18n
+  jruby-openssl
   json
   nokogiri
   rake
-  redcarpet
   rspec
   rspec-http
   simplecov
diff --git a/lib/occi/api/client/client_http.rb b/lib/occi/api/client/client_http.rb
index 31174a7..08c0532 100644
--- a/lib/occi/api/client/client_http.rb
+++ b/lib/occi/api/client/client_http.rb
@@ -1,5 +1,7 @@
 require 'rubygems'
 require 'httparty'
+require 'occi/api/client/http/net_http_fix'
+require 'occi/api/client/http/httparty_fix'
 
 module Occi
   module Api
@@ -9,6 +11,7 @@ class ClientHttp
 
       # HTTParty for raw HTTP requests
       include HTTParty
+
       # TODO: uncomment the following line as JSON is properly implemented in OpenStack
       # headers 'Accept' => 'application/occi+json,text/plain;q=0.8,text/occi;q=0.2'
       headers 'Accept' => 'text/plain,text/occi;q=0.2'
@@ -586,7 +589,9 @@ def change_auth(auth_options)
             raise ArgumentError, "The file specified in 'user_cert' does not exist!" unless File.exists? @auth_options[:user_cert]
 
             self.class.pem File.read(@auth_options[:user_cert]), @auth_options[:user_cert_password]
-            self.class.ssl_ca_path @auth_options[:ca_path] unless @auth_options[:ca_path].nil? or @auth_options[:ca_path].empty?
+            self.class.ssl_ca_path @auth_options[:ca_path] unless @auth_options[:ca_path].nil?
+            self.class.ssl_ca_file @auth_options[:ca_file] unless @auth_options[:ca_file].nil?
+            self.class.ssl_extra_chain_cert certs_to_file_ary(@auth_options[:proxy_ca]) unless @auth_options[:proxy_ca].nil?
           when "none", nil
             # do nothing
           else
@@ -594,6 +599,19 @@ def change_auth(auth_options)
         end
       end
 
+      # Reads X.509 certificates from a file to an array.
+      #
+      # @example
+      #    certs_to_file_ary "~/.globus/usercert.pem"
+      #      # => [#<String>, #<String>, ...]
+      #
+      # @param [String] Path to a PEM file containing certificates 
+      # @return [Array<String>] An array of read certificates
+      def certs_to_file_ary(ca_file)
+        # TODO: read and separate multiple certificates
+        [] << File.read(ca_file)
+      end
+
       # Performs GET request and parses the responses to collections.
       #
       # @example
diff --git a/lib/occi/api/client/http/httparty_fix.rb b/lib/occi/api/client/http/httparty_fix.rb
new file mode 100644
index 0000000..f4a47fd
--- /dev/null
+++ b/lib/occi/api/client/http/httparty_fix.rb
@@ -0,0 +1,53 @@
+module HTTParty
+  class ConnectionAdapter
+
+    private
+
+    def attach_ssl_certificates(http, options)
+      if http.use_ssl?
+        http.verify_mode = OpenSSL::SSL::VERIFY_NONE
+
+        # Client certificate authentication
+        if options[:pem]
+          http.cert = OpenSSL::X509::Certificate.new(options[:pem])
+          http.key = OpenSSL::PKey::RSA.new(options[:pem], options[:pem_password])
+          http.verify_mode = OpenSSL::SSL::VERIFY_PEER
+        end
+
+        # Set chain of client certificates
+        if options[:ssl_extra_chain_cert]
+          http.extra_chain_cert = []
+
+          options[:ssl_extra_chain_cert].each do |p_ca|
+            http.extra_chain_cert << OpenSSL::X509::Certificate.new(p_ca)
+          end
+        end
+
+        # SSL certificate authority file and/or directory
+        if options[:ssl_ca_file]
+          http.ca_file = options[:ssl_ca_file]
+          http.verify_mode = OpenSSL::SSL::VERIFY_PEER
+        end
+
+        if options[:ssl_ca_path]
+          http.ca_path = options[:ssl_ca_path]
+          http.verify_mode = OpenSSL::SSL::VERIFY_PEER
+        end
+
+        # This is only Ruby 1.9+
+        if options[:ssl_version] && http.respond_to?(:ssl_version=)
+          http.ssl_version = options[:ssl_version]
+        end
+      end
+    end
+
+  end
+
+  module ClassMethods
+
+    def ssl_extra_chain_cert(ary_of_certs)
+      default_options[:ssl_extra_chain_cert] = ary_of_certs
+    end
+
+  end
+end
diff --git a/lib/occi/api/client/http/net_http_fix.rb b/lib/occi/api/client/http/net_http_fix.rb
new file mode 100644
index 0000000..882e89f
--- /dev/null
+++ b/lib/occi/api/client/http/net_http_fix.rb
@@ -0,0 +1,46 @@
+##############################################################################
+## Net::HTTP hack allowing the use of X.509 proxy certificates.
+##############################################################################
+
+# When running Ruby 1.8.x, RUBY_ENGINE is not defined
+RUBY_ENGINE = "ruby" unless defined? RUBY_ENGINE
+
+# detect jRuby
+if RUBY_ENGINE == 'jruby'
+  #TODO: add jRuby support, this doesn't work
+  module Net
+    class HTTP
+
+      SSL_ATTRIBUTES = SSL_ATTRIBUTES.concat %w(extra_chain_cert)
+
+      # An Array of certificates that will be sent to the client.
+      attr_accessor :extra_chain_cert
+
+    end
+  end
+else
+  net_http_fix_rby_ver = RUBY_VERSION.split('.')
+
+  # detect old Rubies, tested with 1.8.7-p371
+  if net_http_fix_rby_ver[1] == "8"
+    module Net
+      class HTTP
+
+        # An Array of certificates that will be sent to the client.
+        ssl_context_accessor :extra_chain_cert
+
+      end
+    end
+  else
+    module Net
+      class HTTP
+
+        SSL_ATTRIBUTES = SSL_ATTRIBUTES.concat %w(extra_chain_cert)
+
+        # An Array of certificates that will be sent to the client.
+        attr_accessor :extra_chain_cert
+
+      end
+    end
+  end
+end
diff --git a/lib/occi/bin/occi_opts.rb b/lib/occi/bin/occi_opts.rb
index f8bc72f..a9df473 100644
--- a/lib/occi/bin/occi_opts.rb
+++ b/lib/occi/bin/occi_opts.rb
@@ -32,6 +32,7 @@ def self.parse(args)
         options.auth[:user_cert] = ENV['HOME'] + "/.globus/usercred.pem"
         options.auth[:ca_path] = "/etc/grid-security/certificates"
         options.auth[:username] = "anonymous"
+        options.auth[:ca_file] = nil
 
         options.output_format = :plain
         
@@ -81,17 +82,27 @@ def self.parse(args)
           end
 
           opts.on("-c",
-                  "--ca-path PATH", String, "Path to CA certificates, defaults to '#{options.auth[:ca_path]}'") do |ca_path|
+                  "--ca-path PATH", String, "Path to CA certificates directory, defaults to '#{options.auth[:ca_path]}'") do |ca_path|
             options.auth[:ca_path] = ca_path
           end
 
+          opts.on("-f",
+                  "--ca-file PATH", String, "Path to CA certificates in a file") do |ca_file|
+            options.auth[:ca_file] = ca_file
+          end
+
           opts.on("-x",
-                  "--user-cred X509_CREDENTIALS",
+                  "--user-cred PATH",
                   String,
                   "Path to user's x509 credentials, defaults to '#{options.auth[:user_cert]}'") do |user_cred|
             options.auth[:user_cert] = user_cred
           end
 
+          opts.on("-X",
+                  "--proxy-ca PATH", String, "Path to a file with GSI proxy's CA certificate(s)") do |proxy_ca|
+            options.auth[:proxy_ca] = proxy_ca
+          end
+
           opts.on("-y",
                   "--media-type MEDIA_TYPE",
                   MEDIA_TYPES,