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Cross Device Integration

Overview

Cross Device in a nutshell

Criteo Cross Device enables Criteo to accurately match users across multiple devices. To benefit from Criteo’s Cross Device technology, you will need to add the Cross Device parameter to your existing Criteo OneTag.

Example: Let's assume your customer is browsing products on your website from his mobile device. Using Criteo Cross Device, it will be possible to later show this customer relevant banners on his desktop device.

 

 

The user’s email address will be passed within the Cross Device parameter. To facilitate the protection of Personally Identifiable Information (PII), all email addresses will be hashed (using an SHA-256 algorithm) before being stored on Criteo's servers. Criteo will then use the hash value to match users across each of their devices.

Privacy

The protection of a user’s privacy is a major concern for Criteo’s clients. Criteo does not, nor ever will, store any personal data. To ensure we protect your client’s privacy, Criteo will only store the encrypted email addresses of your customers on its servers. The encryption process cannot be reversed, maintaining anonymity at all times.

Criteo does not collect, nor process any directly Personally Identifiable Information (PII). Instead Criteo uses “pseudonymous” information to match users with Cross Device.

To guarantee maximum protection, Criteo uses the SHA-256 hashing method to encrypt the user’s email addresses. SHA-256 email hashing creates a unique, persistent, identifier that allows Criteo to identify users across the different devices and across different client websites (see above), none of which can be used to identify your customers. Criteo will never store an unhashed email address.
Criteo offers users full transparency through our privacy policy and opt out solutions. In addition to this, we ask our partners to be transparent about our services and methods in their own privacy policy. This means that users can access information about our services at all stages of their navigation and can opt-out of our services at any time.

Methods to enable Criteo Cross Device

To provide the most flexibility possible to its clients, Criteo accepts user’s email addresses, hashed or plain text.

Please use the setEmail event if you are passing the plain text email or the MD5 hashed email.

Before hashing or when passing plain text, all users’ email addresses need to be:

  • Trimmed (removing all spaces before and after the user's email address).
  • Converted to lowercase.
  • Encoded in UTF-8.

Cross Device parameters 

We recommend you send an email address that has already been hashed via a dedicated function (using an MD5 algorithm). Here is an example of the MD5 hashed email sent in the setEmail event:

{ event: "setEmail", email: "b58996c504c5638798eb6b511e6f49af" },

In the event that an unhashed email address is sent, Criteo will then encrypt the user's email address automatically before it is saved in our database. Here is an example of the plain-text email sent in the setEmail event:

{ event: "setEmail", email: "user@example.com" },

In the event that you are unable to pass either an unhashed or hashed email address, please simply pass us an empty string:

{ event: "setEmail", email: "" },

Hashing functions

If you are hasing the user's email addresses before it is passed to Criteo, you can use one of the following functions to ensure proper encryption.

Hashing function using PHP

$source_address = "uSèr@example.Com ";
$processed_address = strtolower($source_address); //convert address to lower case
$processed_address = trim($processed_address); //trimming leading and trailing spaces
$processed_address = mb_convert_encoding($processed_address, "UTF-8", "ISO-8859-1"); //conversion from ISO-8859-1 to UTF-8 (replace "ISO-8859-1" with the source encoding of your string)
$processed_address = md5($processed_address); //hash address with MD5 algorithm
echo "Source e-mail: ".$source_address." | Hashed e-mail: ".$processed_address;

Hashing function using C#  

using System; 
 using System.Collections.Generic; using System.Linq;
 using System.Text;
 using System.Security.Cryptography;
 namespace Sample_EmailHashing_code
 {
     public class CriteoHashedEmailFormatter
     {
         private static MD5 _md5;
         private static MD5 Md5
         {
             get { return _md5 ?? (_md5 = MD5.Create()); }
         }
         private static string Md5Encode(string sourceString)
         {
             byte[] inputBytes = Encoding.UTF8.GetBytes(sourceString);
             byte[] hash = Md5.ComputeHash(inputBytes);
             var sb = new StringBuilder(32);
             foreach (byte b in hash)
                 sb.Append(b.ToString("x2"));
             return sb.ToString();
         }
         public static string HashEmail(string sourceEmail)
         {
             String processedEmail;
             processedEmail = sourceEmail.ToLowerInvariant(); //conversion to lower case
             processedEmail = processedEmail.Trim(); //trimming leading and trailing spaces
             //conversion to UTF-8 and hashing with MD5
             processedEmail = Md5Encode(processedEmail);
             return processedEmail;
         }
     }
     class SampleEmailHashing
     {
         static void Main(string[] args)
         {
             String sourceEmail = "   uSèr@example.Com   ";
             String processedEmail =
CriteoHashedEmailFormatter.HashEmail(sourceEmail);
             Console.WriteLine(processedEmail);
             Console.ReadKey();
         }
     }
 }

 

Hashing function using PHP

Click here to expand

 import java.io.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class SampleEmailHashing {
     public static void main(String[] args) {          
     String sourceEmail = new String(" uSèr@example.Com ");
        String processedEmail = FormatMail(sourceEmail);
        System.out.println(processedEmail);
     }
     //Method to format the source Email, converting to lower case and removing spaces     private static String FormatMail(String mail) {
         String newMail = new String(mail);
         // conversion to lower case characters
         newMail = newMail.toLowerCase();
         //remove empty spaces
         newMail = newMail.trim();
         newMail = md5Java(newMail);      
            
return newMail;
     }
     
//Method to encrypt email address using MD5
     public static String md5Java(String message) {         String digest = null;         try {
             //conversion to UTF-8 and hashing with MD5             MessageDigest md = MessageDigest.getInstance("MD5");
             byte[] hash = md.digest(message.getBytes("UTF-8"));
             StringBuilder sb = new StringBuilder(2 * hash.length);
             for (byte b : hash) {
                 sb.append(String.format("%02x", b & 0xff));
             }
             digest = sb.toString();
         } catch (UnsupportedEncodingException ex) {
             ex.printStackTrace();
         } catch (NoSuchAlgorithmException ex) {
             ex.printStackTrace();
         }         return digest;
     }
}

Hashing function using Perl  

#!/usr/bin/perl
use strict;
use warnings;
use Digest::MD5 qw(md5 md5_hex);
use Encode;
my $original_email  = qw/ uSèr@example.Com /;
my $processed_email = lc($original_email);
    $processed_email =~ s/^\s+//;
    $processed_email =~ s/\s+$//;
    $processed_email = encode_utf8($processed_email);
    $processed_email = md5_hex($processed_email);
print "Original email:\t$original_email\n";
print "Hashed email:\t$processed_email \n";

Hashing function using JavaScript

function utf8_encode(argString) {

  if (argString === null || typeof argString === 'undefined') {
    return '';
  }

  var string = (argString + ''); // .replace(/\r\n/g, "\n").replace(/\r/g, "\n");
  var utftext = '',
    start, end, stringl = 0;

  start = end = 0;
  stringl = string.length;
  for (var n = 0; n < stringl; n++) {
    var c1 = string.charCodeAt(n);
    var enc = null;

    if (c1 < 128) {
      end++;
    } else if (c1 > 127 && c1 < 2048) {
      enc = String.fromCharCode(
        (c1 >> 6) | 192, (c1 & 63) | 128
      );
    } else if ((c1 & 0xF800) != 0xD800) {
      enc = String.fromCharCode(
        (c1 >> 12) | 224, ((c1 >> 6) & 63) | 128, (c1 & 63) | 128
      );
    } else { // surrogate pairs
      if ((c1 & 0xFC00) != 0xD800) {
        throw new RangeError('Unmatched trail surrogate at ' + n);
      }
      var c2 = string.charCodeAt(++n);
      if ((c2 & 0xFC00) != 0xDC00) {
        throw new RangeError('Unmatched lead surrogate at ' + (n - 1));
      }
      c1 = ((c1 & 0x3FF) << 10) + (c2 & 0x3FF) + 0x10000;
      enc = String.fromCharCode(
        (c1 >> 18) | 240, ((c1 >> 12) & 63) | 128, ((c1 >> 6) & 63) | 128, (c1 & 63) | 128
      );
    }
    if (enc !== null) {
      if (end > start) {
        utftext += string.slice(start, end);
      }
      utftext += enc;
      start = end = n + 1;
    }
  }

  if (end > start) {
    utftext += string.slice(start, stringl);
  }

  return utftext;
}


function md5(str) {

  var str = str.toLowerCase();
  var xl;

  var rotateLeft = function(lValue, iShiftBits) {
    return (lValue << iShiftBits) | (lValue >>> (32 - iShiftBits));
  };

  var addUnsigned = function(lX, lY) {
    var lX4, lY4, lX8, lY8, lResult;
    lX8 = (lX & 0x80000000);
    lY8 = (lY & 0x80000000);
    lX4 = (lX & 0x40000000);
    lY4 = (lY & 0x40000000);
    lResult = (lX & 0x3FFFFFFF) + (lY & 0x3FFFFFFF);
    if (lX4 & lY4) {
      return (lResult ^ 0x80000000 ^ lX8 ^ lY8);
    }
    if (lX4 | lY4) {
      if (lResult & 0x40000000) {
        return (lResult ^ 0xC0000000 ^ lX8 ^ lY8);
      } else {
        return (lResult ^ 0x40000000 ^ lX8 ^ lY8);
      }
    } else {
      return (lResult ^ lX8 ^ lY8);
    }
  };

  var _F = function(x, y, z) {
    return (x & y) | ((~x) & z);
  };
  var _G = function(x, y, z) {
    return (x & z) | (y & (~z));
  };
  var _H = function(x, y, z) {
    return (x ^ y ^ z);
  };
  var _I = function(x, y, z) {
    return (y ^ (x | (~z)));
  };

  var _FF = function(a, b, c, d, x, s, ac) {
    a = addUnsigned(a, addUnsigned(addUnsigned(_F(b, c, d), x), ac));
    return addUnsigned(rotateLeft(a, s), b);
  };

  var _GG = function(a, b, c, d, x, s, ac) {
    a = addUnsigned(a, addUnsigned(addUnsigned(_G(b, c, d), x), ac));
    return addUnsigned(rotateLeft(a, s), b);
  };

  var _HH = function(a, b, c, d, x, s, ac) {
    a = addUnsigned(a, addUnsigned(addUnsigned(_H(b, c, d), x), ac));
    return addUnsigned(rotateLeft(a, s), b);
  };

  var _II = function(a, b, c, d, x, s, ac) {
    a = addUnsigned(a, addUnsigned(addUnsigned(_I(b, c, d), x), ac));
    return addUnsigned(rotateLeft(a, s), b);
  };

  var convertToWordArray = function(str) {
    var lWordCount;
    var lMessageLength = str.length;
    var lNumberOfWords_temp1 = lMessageLength + 8;
    var lNumberOfWords_temp2 = (lNumberOfWords_temp1 - (lNumberOfWords_temp1 % 64)) / 64;
    var lNumberOfWords = (lNumberOfWords_temp2 + 1) * 16;
    var lWordArray = new Array(lNumberOfWords - 1);
    var lBytePosition = 0;
    var lByteCount = 0;
    while (lByteCount < lMessageLength) {
      lWordCount = (lByteCount - (lByteCount % 4)) / 4;
      lBytePosition = (lByteCount % 4) * 8;
      lWordArray[lWordCount] = (lWordArray[lWordCount] | (str.charCodeAt(lByteCount) << lBytePosition));
      lByteCount++;
    }
    lWordCount = (lByteCount - (lByteCount % 4)) / 4;
    lBytePosition = (lByteCount % 4) * 8;
    lWordArray[lWordCount] = lWordArray[lWordCount] | (0x80 << lBytePosition);
    lWordArray[lNumberOfWords - 2] = lMessageLength << 3;
    lWordArray[lNumberOfWords - 1] = lMessageLength >>> 29;
    return lWordArray;
  };

  var wordToHex = function(lValue) {
    var wordToHexValue = '',
      wordToHexValue_temp = '',
      lByte, lCount;
    for (lCount = 0; lCount <= 3; lCount++) {
      lByte = (lValue >>> (lCount * 8)) & 255;
      wordToHexValue_temp = '0' + lByte.toString(16);
      wordToHexValue = wordToHexValue + wordToHexValue_temp.substr(wordToHexValue_temp.length - 2, 2);
    }
    return wordToHexValue;
  };

  var x = [],
    k, AA, BB, CC, DD, a, b, c, d, S11 = 7,
    S12 = 12,
    S13 = 17,
    S14 = 22,
    S21 = 5,
    S22 = 9,
    S23 = 14,
    S24 = 20,
    S31 = 4,
    S32 = 11,
    S33 = 16,
    S34 = 23,
    S41 = 6,
    S42 = 10,
    S43 = 15,
    S44 = 21;

  str = utf8_encode(str);
  x = convertToWordArray(str);
  a = 0x67452301;
  b = 0xEFCDAB89;
  c = 0x98BADCFE;
  d = 0x10325476;

  xl = x.length;
  for (k = 0; k < xl; k += 16) {
    AA = a;
    BB = b;
    CC = c;
    DD = d;
    a = _FF(a, b, c, d, x[k + 0], S11, 0xD76AA478);
    d = _FF(d, a, b, c, x[k + 1], S12, 0xE8C7B756);
    c = _FF(c, d, a, b, x[k + 2], S13, 0x242070DB);
    b = _FF(b, c, d, a, x[k + 3], S14, 0xC1BDCEEE);
    a = _FF(a, b, c, d, x[k + 4], S11, 0xF57C0FAF);
    d = _FF(d, a, b, c, x[k + 5], S12, 0x4787C62A);
    c = _FF(c, d, a, b, x[k + 6], S13, 0xA8304613);
    b = _FF(b, c, d, a, x[k + 7], S14, 0xFD469501);
    a = _FF(a, b, c, d, x[k + 8], S11, 0x698098D8);
    d = _FF(d, a, b, c, x[k + 9], S12, 0x8B44F7AF);
    c = _FF(c, d, a, b, x[k + 10], S13, 0xFFFF5BB1);
    b = _FF(b, c, d, a, x[k + 11], S14, 0x895CD7BE);
    a = _FF(a, b, c, d, x[k + 12], S11, 0x6B901122);
    d = _FF(d, a, b, c, x[k + 13], S12, 0xFD987193);
    c = _FF(c, d, a, b, x[k + 14], S13, 0xA679438E);
    b = _FF(b, c, d, a, x[k + 15], S14, 0x49B40821);
    a = _GG(a, b, c, d, x[k + 1], S21, 0xF61E2562);
    d = _GG(d, a, b, c, x[k + 6], S22, 0xC040B340);
    c = _GG(c, d, a, b, x[k + 11], S23, 0x265E5A51);
    b = _GG(b, c, d, a, x[k + 0], S24, 0xE9B6C7AA);
    a = _GG(a, b, c, d, x[k + 5], S21, 0xD62F105D);
    d = _GG(d, a, b, c, x[k + 10], S22, 0x2441453);
    c = _GG(c, d, a, b, x[k + 15], S23, 0xD8A1E681);
    b = _GG(b, c, d, a, x[k + 4], S24, 0xE7D3FBC8);
    a = _GG(a, b, c, d, x[k + 9], S21, 0x21E1CDE6);
    d = _GG(d, a, b, c, x[k + 14], S22, 0xC33707D6);
    c = _GG(c, d, a, b, x[k + 3], S23, 0xF4D50D87);
    b = _GG(b, c, d, a, x[k + 8], S24, 0x455A14ED);
    a = _GG(a, b, c, d, x[k + 13], S21, 0xA9E3E905);
    d = _GG(d, a, b, c, x[k + 2], S22, 0xFCEFA3F8);
    c = _GG(c, d, a, b, x[k + 7], S23, 0x676F02D9);
    b = _GG(b, c, d, a, x[k + 12], S24, 0x8D2A4C8A);
    a = _HH(a, b, c, d, x[k + 5], S31, 0xFFFA3942);
    d = _HH(d, a, b, c, x[k + 8], S32, 0x8771F681);
    c = _HH(c, d, a, b, x[k + 11], S33, 0x6D9D6122);
    b = _HH(b, c, d, a, x[k + 14], S34, 0xFDE5380C);
    a = _HH(a, b, c, d, x[k + 1], S31, 0xA4BEEA44);
    d = _HH(d, a, b, c, x[k + 4], S32, 0x4BDECFA9);
    c = _HH(c, d, a, b, x[k + 7], S33, 0xF6BB4B60);
    b = _HH(b, c, d, a, x[k + 10], S34, 0xBEBFBC70);
    a = _HH(a, b, c, d, x[k + 13], S31, 0x289B7EC6);
    d = _HH(d, a, b, c, x[k + 0], S32, 0xEAA127FA);
    c = _HH(c, d, a, b, x[k + 3], S33, 0xD4EF3085);
    b = _HH(b, c, d, a, x[k + 6], S34, 0x4881D05);
    a = _HH(a, b, c, d, x[k + 9], S31, 0xD9D4D039);
    d = _HH(d, a, b, c, x[k + 12], S32, 0xE6DB99E5);
    c = _HH(c, d, a, b, x[k + 15], S33, 0x1FA27CF8);
    b = _HH(b, c, d, a, x[k + 2], S34, 0xC4AC5665);
    a = _II(a, b, c, d, x[k + 0], S41, 0xF4292244);
    d = _II(d, a, b, c, x[k + 7], S42, 0x432AFF97);
    c = _II(c, d, a, b, x[k + 14], S43, 0xAB9423A7);
    b = _II(b, c, d, a, x[k + 5], S44, 0xFC93A039);
    a = _II(a, b, c, d, x[k + 12], S41, 0x655B59C3);
    d = _II(d, a, b, c, x[k + 3], S42, 0x8F0CCC92);
    c = _II(c, d, a, b, x[k + 10], S43, 0xFFEFF47D);
    b = _II(b, c, d, a, x[k + 1], S44, 0x85845DD1);
    a = _II(a, b, c, d, x[k + 8], S41, 0x6FA87E4F);
    d = _II(d, a, b, c, x[k + 15], S42, 0xFE2CE6E0);
    c = _II(c, d, a, b, x[k + 6], S43, 0xA3014314);
    b = _II(b, c, d, a, x[k + 13], S44, 0x4E0811A1);
    a = _II(a, b, c, d, x[k + 4], S41, 0xF7537E82);
    d = _II(d, a, b, c, x[k + 11], S42, 0xBD3AF235);
    c = _II(c, d, a, b, x[k + 2], S43, 0x2AD7D2BB);
    b = _II(b, c, d, a, x[k + 9], S44, 0xEB86D391);
    a = addUnsigned(a, AA);
    b = addUnsigned(b, BB);
    c = addUnsigned(c, CC);
    d = addUnsigned(d, DD);
  }

  var temp = wordToHex(a) + wordToHex(b) + wordToHex(c) + wordToHex(d);

  return temp.toLowerCase();
}
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