Re: [VOTE] Timing attack safe string comparison function

Hi all, On Fri, Feb 7, 2014 at 8:05 AM, Yasuo Ohgaki <yohgaki@ohgaki.net> wrote: > I made SipHash version of str_compare() as a sample. > There is timing safe php_compare(), which is stolen from BSD. > > > https://github.com/yohgaki/php-src/compare/PHP-5.6-rfc-hash-compare > > [yohgaki@dev github-php-src]$ ./php-bin -r 'var_dump(str_compare("abc", > "abc"));' > bool(true) > [yohgaki@dev github-php-src]$ ./php-bin -r > 'var_dump(str_compare("asfasdf", "slkjojoeiwrj"));' > bool(false) > > It's quick patch made less than 30 min. > So it can be improved, I suppose. > I thought it would be better to compare performance difference. Added more functions to play with. There are bool str_siphash_compare(str, str) - siphash. timing safe. (64bit) bool str_xxhash32_compare(str, str) - xxhash. timing safe. (32bit) bool str_md5_compare(str, str) - md5. Timing safe (128bit) bool str_byte_compare(str, str) - Byte compare. Timing safe. No division. bool str_byte_compare2(str, str) - Byte compare. Timing safe. With division. (Modulo as this RFC) bool str_compare(str, str) - plain strncmp(). Not timing safe. I didn't took bench mark and did minimum tests. I appreciate if anyone take benchmark. Regards, -- Yasuo Ohgaki yohgaki@ohgaki.netH