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author | Aaron Patterson <aaron.patterson@gmail.com> | 2015-10-29 10:42:44 -0700 |
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committer | Aaron Patterson <aaron.patterson@gmail.com> | 2016-01-22 14:57:14 -0800 |
commit | a6fa3960c3a149e83eb2ff057be4472a82958e3d (patch) | |
tree | 5f1fec107a443ee54507b9001edfcee8483d551c /activesupport/lib/active_support/security_utils.rb | |
parent | 9dc8ddc39424818a3d713a353353ac20cb431218 (diff) | |
download | rails-a6fa3960c3a149e83eb2ff057be4472a82958e3d.tar.gz rails-a6fa3960c3a149e83eb2ff057be4472a82958e3d.tar.bz2 rails-a6fa3960c3a149e83eb2ff057be4472a82958e3d.zip |
use secure string comparisons for basic auth username / password
this will avoid timing attacks against applications that use basic auth.
Conflicts:
activesupport/lib/active_support/security_utils.rb
Conflicts:
actionpack/lib/action_controller/metal/http_authentication.rb
CVE-2015-7576
Diffstat (limited to 'activesupport/lib/active_support/security_utils.rb')
-rw-r--r-- | activesupport/lib/active_support/security_utils.rb | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/security_utils.rb b/activesupport/lib/active_support/security_utils.rb new file mode 100644 index 0000000000..9be8613ada --- /dev/null +++ b/activesupport/lib/active_support/security_utils.rb @@ -0,0 +1,27 @@ +require 'digest' + +module ActiveSupport + module SecurityUtils + # Constant time string comparison. + # + # The values compared should be of fixed length, such as strings + # that have already been processed by HMAC. This should not be used + # on variable length plaintext strings because it could leak length info + # via timing attacks. + def secure_compare(a, b) + return false unless a.bytesize == b.bytesize + + l = a.unpack "C#{a.bytesize}" + + res = 0 + b.each_byte { |byte| res |= byte ^ l.shift } + 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 |