Why Do My PHP Hex Conversions Fail During XOR Encryption?

Conversion Between Hex and Strings in PHP

Problem:

When converting between strings and hexadecimal representations in PHP, issues arise when using XOR encryption. Specifically, the conversion from string to hex may produce incorrect results.

Code Samples:

function strToHex($string){
    $hex='';
    for ($i=0; $i < strlen($string); $i++){
        $hex .= dechex(ord($string[$i]));
    }
    return $hex;
}


function hexToStr($hex){
    $string='';
    for ($i=0; $i < strlen($hex)-1; $i+=2){
        $string .= chr(hexdec($hex[$i].$hex[$i+1]));
    }
    return $string;
}

Solution:

Instead of using the provided conversion functions, utilize the built-in functions bin2hex and hex2bin.

bin2hex("that's all you need");
# 74686174277320616c6c20796f75206e656564

hex2bin('74686174277320616c6c20796f75206e656564');
# that's all you need

These functions handle binary data properly and produce accurate hexadecimal representations and string conversions.

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