PHP Hash_equals Polyfill

Source: Internet
Author: User
In Php.net see a version, but there are a lot of downvotes, do not know why.

if(!function_exists('hash_equals')) {  function hash_equals($str1, $str2) {    if(strlen($str1) != strlen($str2)) {      return false;    } else {      $res = $str1 ^ $str2;      $ret = 0;      for($i = strlen($res) - 1; $i >= 0; $i--) $ret |= ord($res[$i]);      return !$ret;    }  }}

If this function is really bad, please explain why, it is best to give alternative solutions, thank you.

From StackOverflow see it as follows:

PHP_FUNCTION(hash_equals){    /* ... */    if (Z_STRLEN_P(known_zval) != Z_STRLEN_P(user_zval)) {        RETURN_FALSE;    }    /* ... */    /* This is security sensitive code. Do not optimize this for speed. */    for (j = 0; j < Z_STRLEN_P(known_zval); j++) {        result |= known_str[j] ^ user_str[j];    }    RETURN_BOOL(0 == result);}

Looks like there's nothing on the Polyfill.

Reply content:

In Php.net see a version, but there are a lot of downvotes, do not know why.

if(!function_exists('hash_equals')) {  function hash_equals($str1, $str2) {    if(strlen($str1) != strlen($str2)) {      return false;    } else {      $res = $str1 ^ $str2;      $ret = 0;      for($i = strlen($res) - 1; $i >= 0; $i--) $ret |= ord($res[$i]);      return !$ret;    }  }}

If this function is really bad, please explain why, it is best to give alternative solutions, thank you.

From StackOverflow see it as follows:

PHP_FUNCTION(hash_equals){    /* ... */    if (Z_STRLEN_P(known_zval) != Z_STRLEN_P(user_zval)) {        RETURN_FALSE;    }    /* ... */    /* This is security sensitive code. Do not optimize this for speed. */    for (j = 0; j < Z_STRLEN_P(known_zval); j++) {        result |= known_str[j] ^ user_str[j];    }    RETURN_BOOL(0 == result);}

Looks like there's nothing on the Polyfill.

Because the type is not strict, it can be exploited if an attacker is able to control the type of the argument in some way

phpfunction bug_hash_equals($str1, $str2) {    if(strlen($str1) != strlen($str2)) {      return false;    } else {      $res = $str1 ^ $str2;      $ret = 0;      for($i = strlen($res) - 1; $i >= 0; $i--) $ret |= ord($res[$i]);      return !$ret;    }}var_dump(bug_hash_equals('aaabbb', 0.0001));//true

http://sandbox.onlinephpfunctions.com/code/e7c978d047486534441403a88680cefb85b1a48c

  • Related Article

    Contact Us

    The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

    If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

    A Free Trial That Lets You Build Big!

    Start building with 50+ products and up to 12 months usage for Elastic Compute Service

    • Sales Support

      1 on 1 presale consultation

    • After-Sales Support

      24/7 Technical Support 6 Free Tickets per Quarter Faster Response

    • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.