UTF-8文字コードを利用したN進数変換関数。MD5ハッシュを10桁の文字列に圧縮できます。詳細 https://blog.keinos.com/20170720_2810

1-sample.php

<?php
// Include user function
include('2-mb_base_encode.php');

// Input string
$s = 'This is a sample string to be hashed.';

// Calculate samples
$result1 = $s;
$result2 = md5($s);
$result3 = mb_base_encode(hexdec(md5($s)));

// Output
echo2($result1);  // 'This is a sample string to be hashed.'
echo2($result2);  // 'baad33e1e97f316b9750c27c86bf64d6'
echo2($result3);  // '䙔倁屩劷䋾彨䏔䂌䤘剒'

// etc
/**
 * Just echoes string with PHP_EOL
 * 
 * @param  string
 * return  string
 */
function echo2($s){
    echo $s . PHP_EOL;
}

?>

2-mb_base_encode.php

<?php

/**
 * Returns base Nth encoded string from decimal number input.
 *
 * @param  integer $number Decimal number to encode
 * @return string          Encoded string
 */
function mb_base_encode($number)
{
    $char = array_merge(
        mb_range('䀀', '䶵'), // U+4000 - U+4DB5
        mb_range('一', '俿'), // U+4E00 - U+4FFF
        mb_range('倀', '忿') //  U+5000 - U+5FFF
        // REF: http://www.utf8-chartable.com/unicode-utf8-table.pl?start=16384&number=1024
    );

    $base   = count($char);
    $result = "";
    while ($number > 0) {
        $result = $char[ fmod($number, $base) ] . $result;
        $number = floor($number / $base);
    }

    return ( $result == "" ) ? 0 : $result;
}

/* ---------------------------------------------------------------------
    This function requires mb_range.
    https://gist.github.com/rodneyrehm/1306118
   --------------------------------------------------------------------- */

/**
 * multibyte string compatible range('A', 'Z')
 *
 * @param string $start Character to start from (included)
 * @param string $end Character to end with (included)
 * @return array list of characters in unicode alphabet from $start to $end
 * @author Rodney Rehm
 */
function mb_range($start, $end) {
    // if start and end are the same, well, there's nothing to do
    if ($start == $end) {
        return array($start);
    }
    
    $_result = array();
    // get unicodes of start and end
    list(, $_start, $_end) = unpack("N*", mb_convert_encoding($start . $end, "UTF-32BE", "UTF-8"));
    // determine movement direction
    $_offset = $_start < $_end ? 1 : -1;
    $_current = $_start;
    while ($_current != $_end) {
        $_result[] = mb_convert_encoding(pack("N*", $_current), "UTF-8", "UTF-32BE");
        $_current += $_offset;
    }
    $_result[] = $end;
    return $_result;
}

?>

functions.php

<?php

function mb_md5(string $string, array $chars)
{
    return mb_base_encode(hexdec(md5($string)), $chars);
}

function getCharsToUse(): array
{
    return array_merge(
        mb_range('䀀', '䶵'), // U+4000 - U+4DB5
        mb_range('一', '俿'), // U+4E00 - U+4FFF
        mb_range('倀', '忿') //  U+5000 - U+5FFF
        // REF: http://www.utf8-chartable.com/unicode-utf8-table.pl?start=16384&number=1024
    );
}

/**
 * Returns base Nth encoded string from decimal number input.
 */
function mb_base_encode(float $number, array $chars): string
{
    $number = (double) $number;
    $base   = count($chars);
    $result = "";
    while ($number > 0) {
        $result = $chars[ fmod($number, $base) ] . $result;
        $number = floor($number / $base);
    }

    return ( $result == "" ) ? "0" : $result;
}

/**
 * multibyte string compatible range('A', 'Z').
 *
 * @param  string $start Character to start from (included)
 * @param  string $end   Character to end with (included)
 * @return array         List of characters in unicode alphabet from $start to $end
 * @note   This function requires mb_range.
 * @ref    https://gist.github.com/rodneyrehm/1306118
 */
function mb_range(string $start, string $end): array
{
    // if start and end are the same, well, there's nothing to do
    if ($start == $end) {
        return array($start);
    }
    
    $_result = array();
    // get unicodes of start and end
    list(, $_start, $_end) = unpack("N*", mb_convert_encoding($start . $end, "UTF-32BE", "UTF-8"));
    // determine movement direction
    $_offset = $_start < $_end ? 1 : -1;
    $_current = $_start;
    while ($_current != $_end) {
        $_result[] = mb_convert_encoding(pack("N*", $_current), "UTF-8", "UTF-32BE");
        $_current += $_offset;
    }
    $_result[] = $end;
    return $_result;
}

Main.php

<?php
// Include user function
include('functions.php');

// Input string
$s = 'This is a sample string to be hashed.';

// Characters to use
$chars = getCharsToUse();
echoEOL('Number of characters', count($chars));

// Calculate samples
$result1 = $s;
$result2 = md5($s);
$result3 = mb_base_encode(hexdec(md5($s)), $chars);
$result4 = mb_md5($s, $chars);
$result5 = mb_base_encode(hexdec('baad33e1e97f316b9750c27c86bf64d7'), $chars);

// Output
echoEOL('Original String', $result1);  // 'This is a sample string to be hashed.'
echoEOL('Pure MD5 hashed string', $result2);  // 'baad33e1e97f316b9750c27c86bf64d6'
echoEOL('Multibyte base encoded', $result3);  // '䙔倁屩劷䋾彨䏔䂌䤘剒'
echoEOL('Same above but alies', $result4);  // '䙔倁屩劷䋾彨䏔䂌䤘剒'
echoEOL('Little change value', $result5);

// etc
function echoEOL(string $title, string $s)
{
    echo "${title}:\t${s}" . PHP_EOL;
}