Dutch PHP Conference 2019

The Spoofchecker class

(PHP 5 >= 5.4.0, PHP 7, PECL intl >= 2.0.0)


This class is provided because Unicode contains large number of characters and incorporates the varied writing systems of the world and their incorrect usage can expose programs or systems to possible security attacks using characters similarity.

Provided methods allow to check whether an individual string is likely an attempt at confusing the reader (spoof detection), such as "pаypаl" spelled with Cyrillic 'а' characters.

Class synopsis

Spoofchecker {
/* Constants */
const integer SINGLE_SCRIPT_CONFUSABLE = 1 ;
const integer MIXED_SCRIPT_CONFUSABLE = 2 ;
const integer WHOLE_SCRIPT_CONFUSABLE = 4 ;
const integer ANY_CASE = 8 ;
const integer SINGLE_SCRIPT = 16 ;
const integer INVISIBLE = 32 ;
const integer CHAR_LIMIT = 64 ;
/* Methods */
public bool areConfusable ( string $str1 , string $str2 [, string &$error ] )
public __construct ( void )
public bool isSuspicious ( string $text [, string &$error ] )
public void setAllowedLocales ( string $locale_list )
public void setChecks ( int $checks )

Predefined Constants








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User Contributed Notes 2 notes

1 year ago
From http://icu-project.org/apiref/icu4j/com/ibm/icu/text/SpoofChecker.html :
SINGLE_SCRIPT_CONFUSABLE: indicates that the two strings are visually confusable and that they are from the same script
MIXED_SCRIPT_CONFUSABLE: indicates that the two strings are visually confusable and that they are NOT from the same script
WHOLE_SCRIPT_CONFUSABLE: indicates that the two strings are visually confusable and that they are NOT from the same script BUT both of them are single-script strings
ANY_CASE: Deprecated.
SINGLE_SCRIPT: Deprecated.
INVISIBLE: Check an identifier for the presence of invisible characters, such as zero-width spaces, or character sequences that are likely not to display, such as multiple occurrences of the same non-spacing mark.
CHAR_LIMIT: Check that an identifier contains only characters from a specified set of acceptable characters.

Explanation of whole script, mixed script and single script confusables in UTS 39 section 4 : http://unicode.org/reports/tr39/#Confusable_Detection

Details from Java SpoofChecker class at http://icu-project.org/apiref/icu4j/com/ibm/icu/text/SpoofChecker.html
7 months ago
Spoofchecker yields false positives by defaut when Whole-Script Confusables (WSC) and Mixed-Script Confusables (MSC) checks are used.
They have been deprecated since ICU 58:

Workarounds: upgrade ICU to 58+, or avoid the MSC and WSC checks with Spoofcheckers' setChecks() function.
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