Why HMAC sha256 return different value on PHP & Javascript - Stack Overflow

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I am trying to build a HMAC SHA256 string in Javascript using CryptoJS, my existing code is written in PHP using the Akamai library.

In some cases I am getting different results pared to PHP & I am unable to understand why it is giving me different results

    /* 
       <php> Using native hash_hmac
       Generating key by concatenating char 
    */ 

      $signature1 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", chr(63));
      $signature2 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", chr(63) . chr(23));
      $signature3 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", chr(63) . chr(23) . chr(253));

    /*
       here is result from php
       signature1 : 3e086bb48ab9aafa85661f9ce1b7dac49befddf117ce2a42d93c92b6abe513ce ( matched: same as JavaScript)
       signature2 : 3667dd414a50f68f7ce083e540f27f68f7d0f18617b1fb1e4788bffeaeab59f6( matched: same as JavaScript)
       signature3 : dd5a20041661046fdee871c8b9e77b3190fbbf85937c098090a1d524719b6aa9 ( not matched: diff from JavaScript)
    */


    /* 
       <JavaScript> using CryptoJS
       Generating key by concatenating three char 
    */ 

    var signature1 = CryptoJS.HmacSHA256("st=1453362060~exp=1453363260~acl=/*", String.fromCharCode(63));
    var signature2 = CryptoJS.HmacSHA256("st=1453362060~exp=1453363260~acl=/*", String.fromCharCode(63) + String.fromCharCode(23));
    var signature3 = CryptoJS.HmacSHA256("st=1453362060~exp=1453363260~acl=/*", String.fromCharCode(63) + String.fromCharCode(23) + String.fromCharCode(253));

    /* 
       here is result from JavaScript
       signature1 : 3e086bb48ab9aafa85661f9ce1b7dac49befddf117ce2a42d93c92b6abe513ce ( matched: same as php)
       signature2 : 3667dd414a50f68f7ce083e540f27f68f7d0f18617b1fb1e4788bffeaeab59f6 ( matched: same as php)
       signature3 : 28075dc75de9f22f83e87772f09a89efb007f2e298167686832eff122ef6eb08 ( not matched: diff from php)
    */

First two HMAC values are matching but when I append the third char it produces different results, Can anyone please explain why this is.

here is
PHPFiddle & JSFiddle

I am trying to build a HMAC SHA256 string in Javascript using CryptoJS, my existing code is written in PHP using the Akamai library.

In some cases I am getting different results pared to PHP & I am unable to understand why it is giving me different results

    /* 
       <php> Using native hash_hmac
       Generating key by concatenating char 
    */ 

      $signature1 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", chr(63));
      $signature2 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", chr(63) . chr(23));
      $signature3 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", chr(63) . chr(23) . chr(253));

    /*
       here is result from php
       signature1 : 3e086bb48ab9aafa85661f9ce1b7dac49befddf117ce2a42d93c92b6abe513ce ( matched: same as JavaScript)
       signature2 : 3667dd414a50f68f7ce083e540f27f68f7d0f18617b1fb1e4788bffeaeab59f6( matched: same as JavaScript)
       signature3 : dd5a20041661046fdee871c8b9e77b3190fbbf85937c098090a1d524719b6aa9 ( not matched: diff from JavaScript)
    */


    /* 
       <JavaScript> using CryptoJS
       Generating key by concatenating three char 
    */ 

    var signature1 = CryptoJS.HmacSHA256("st=1453362060~exp=1453363260~acl=/*", String.fromCharCode(63));
    var signature2 = CryptoJS.HmacSHA256("st=1453362060~exp=1453363260~acl=/*", String.fromCharCode(63) + String.fromCharCode(23));
    var signature3 = CryptoJS.HmacSHA256("st=1453362060~exp=1453363260~acl=/*", String.fromCharCode(63) + String.fromCharCode(23) + String.fromCharCode(253));

    /* 
       here is result from JavaScript
       signature1 : 3e086bb48ab9aafa85661f9ce1b7dac49befddf117ce2a42d93c92b6abe513ce ( matched: same as php)
       signature2 : 3667dd414a50f68f7ce083e540f27f68f7d0f18617b1fb1e4788bffeaeab59f6 ( matched: same as php)
       signature3 : 28075dc75de9f22f83e87772f09a89efb007f2e298167686832eff122ef6eb08 ( not matched: diff from php)
    */

First two HMAC values are matching but when I append the third char it produces different results, Can anyone please explain why this is.

here is
PHPFiddle & JSFiddle

• javascript
• php
• sha256
• hmac
• cryptojs

Share Improve this question Follow edited Aug 17, 2016 at 15:59 jasonlam604 1,45422 gold badges1616 silver badges2525 bronze badges asked Jan 22, 2016 at 7:28 Anil GuptaAnil Gupta 2,40944 gold badges2525 silver badges3131 bronze badges

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1 Answer 1

Sorted by: Reset to default 5

CryptoJS add UTF8 encoding in "Key" while creating hash sha256 so that we are getting different value.

If i wrap utf8_encode in PHP side then we will get same hmac value as pare to JavaScript

     // <php>
     $key = chr(63) . chr(23) . chr(253);
     signature3 = hash_hmac('SHA256', "st=1453362060~exp=1453363260~acl=/*", utf8_encode($key));

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