SHA256 Hasher – Hashing Email, Phone Number (PII Data) with Google Tag Manager

You are not allowed to directly collect PII Data (Personally Identifiable Information). Collecting PII data violates the terms and conditions of Google Analytics. Many tracking platforms require sending hashed values of PII data. However, there is no straightforward way to hash values with Google Tag Manager. To address this issue, I have recently written a nice code solution which will help hash user data using the recommended hashing mechanism called SHA-256.

In the following tutorial, I have shared everything in detail.

Custom JavaScript Variable for GTM – (SHA-256)

function() {
    return sha256( {{value}} ); //replace {{value}} with right variable

/**
* Author: Md Hasanuzzamna
* Linkedin: https://linkedin.com/in/md-h
* Youtube: https://youtube.com/@leomeasure
* Email: info@leomeasure.com
*/

    function sha256(r){if(r){r=r.toString();for(var $,_,o=Math.pow,f=o(2,32),t="length",a="",n=[],h=8*r[t],i=sha256.h=sha256.h||[],c=sha256.k=sha256.k||[],e=c[t],s={},u=2;e<64;u++)if(!s[u]){for($=0;$<313;$+=u)s[$]=u;i[e]=o(u,.5)*f|0,c[e++]=o(u,1/3)*f|0}for(r+="\x80";r[t]%64-56;)r+="\0";for($=0;$<r[t];$++){if((_=r.charCodeAt($))>>8)return;n[$>>2]|=_<<(3-$)%4*8}for(_=0,n[n[t]]=h/f|0,n[n[t]]=h;_<n[t];){var v=n.slice(_,_+=16),g=i;for($=0,i=i.slice(0,8);$<64;$++){var l=v[$-15],k=v[$-2],x=i[0],S=i[4],d=i[7]+(A(S,6)^A(S,11)^A(S,25))+(S&i[5]^~S&i[6])+c[$]+(v[$]=$<16?v[$]:v[$-16]+(A(l,7)^A(l,18)^l>>>3)+v[$-7]+(A(k,17)^A(k,19)^k>>>10)|0),p=(A(x,2)^A(x,13)^A(x,22))+(x&i[1]^x&i[2]^i[1]&i[2]);(i=[d+p|0].concat(i))[4]=i[4]+d|0}for($=0;$<8;$++)i[$]=i[$]+g[$]|0}for($=0;$<8;$++)for(_=3;_+1;_--){var w=i[$]>>8*_&255;a+=(w<16?0:"")+w.toString(16)}return a}function A(r,$){return r>>>$|r<<32-$}}
}