use secure string comparisons for basic auth username / password

this will avoid timing attacks against applications that use basic auth.

CVE-2015-7576

1 files changed, 7 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/security_utils.rb b/activesupport/lib/active_support/security_utils.rb
index 64c4801179..9be8613ada 100644
--- a/activesupport/lib/active_support/security_utils.rb
+++ b/activesupport/lib/active_support/security_utils.rb
@@ -1,3 +1,5 @@
+require 'digest'
+
 module ActiveSupport
   module SecurityUtils
     # Constant time string comparison.
@@ -16,5 +18,10 @@ module ActiveSupport
       res == 0
     end
     module_function :secure_compare
+
+    def variable_size_secure_compare(a, b) # :nodoc:
+      secure_compare(::Digest::SHA256.hexdigest(a), ::Digest::SHA256.hexdigest(b))
+    end
+    module_function :variable_size_secure_compare
   end
 end