我正在寻找一个PHP函数，用于创建字符串或文件的短哈希，类似于tinyurl.com
等网址缩短网站哈希值不应超过8个字符。
答案 0 :(得分：147)
TinyURL不会散列任何内容，它使用Base 36整数（甚至是62，使用小写和大写字母）来指示要访问的记录。
基础36到整数：
intval($str, 36);
整数到基数36：
base_convert($val, 10, 36);
那么，而不是重定向到/url/1234之类的路线，而不是/url/ax。这比散列更多地使用，因为不会发生冲突。通过这种方式，您可以轻松检查是否存在URL并在基础36中返回正确的现有ID，而无需用户知道它已存在于数据库中。
不要哈希，使用其他基础来做这种事情。 （速度更快，可以防碰撞。）
答案 1 :(得分：76)
我写了一个小lib来从整数生成混淆的哈希值。
http://web.archive.org/web/20130727034425/http://blog.kevburnsjr.com/php-unique-hash
$ids = range(1,10);
foreach($ids as $id) {
echo PseudoCrypt::unhash($id) . "\n";
}m8z2p 8hy5e uqx83 gzwas 38vdh phug6 bqtiv xzslk k8ro9 6hqqy
2015年7月14日：添加下面的实际代码，因为它很难找到：
<?php
/**
* PseudoCrypt by KevBurns (http://blog.kevburnsjr.com/php-unique-hash)
* Reference/source: http://stackoverflow.com/a/1464155/933782
*
* I want a short alphanumeric hash that’s unique and who’s sequence is difficult to deduce.
* I could run it out to md5 and trim the first n chars but that’s not going to be very unique.
* Storing a truncated checksum in a unique field means that the frequency of collisions will increase
* geometrically as the number of unique keys for a base 62 encoded integer approaches 62^n.
* I’d rather do it right than code myself a timebomb. So I came up with this.
*
* Sample Code:
*
* echo "<pre>";
* foreach(range(1, 10) as $n) {
* echo $n." - ";
* $hash = PseudoCrypt::hash($n, 6);
* echo $hash." - ";
* echo PseudoCrypt::unhash($hash)."<br/>";
* }
*
* Sample Results:
* 1 - cJinsP - 1
* 2 - EdRbko - 2
* 3 - qxAPdD - 3
* 4 - TGtDVc - 4
* 5 - 5ac1O1 - 5
* 6 - huKpGQ - 6
* 7 - KE3d8p - 7
* 8 - wXmR1E - 8
* 9 - YrVEtd - 9
* 10 - BBE2m2 - 10
*/
class PseudoCrypt {
/* Key: Next prime greater than 62 ^ n / 1.618033988749894848 */
/* Value: modular multiplicative inverse */
private static $golden_primes = array(
'1' => '1',
'41' => '59',
'2377' => '1677',
'147299' => '187507',
'9132313' => '5952585',
'566201239' => '643566407',
'35104476161' => '22071637057',
'2176477521929' => '294289236153',
'134941606358731' => '88879354792675',
'8366379594239857' => '7275288500431249',
'518715534842869223' => '280042546585394647'
);
/* Ascii : 0 9, A Z, a z */
/* $chars = array_merge(range(48,57), range(65,90), range(97,122)) */
private static $chars62 = array(
0=>48,1=>49,2=>50,3=>51,4=>52,5=>53,6=>54,7=>55,8=>56,9=>57,10=>65,
11=>66,12=>67,13=>68,14=>69,15=>70,16=>71,17=>72,18=>73,19=>74,20=>75,
21=>76,22=>77,23=>78,24=>79,25=>80,26=>81,27=>82,28=>83,29=>84,30=>85,
31=>86,32=>87,33=>88,34=>89,35=>90,36=>97,37=>98,38=>99,39=>100,40=>101,
41=>102,42=>103,43=>104,44=>105,45=>106,46=>107,47=>108,48=>109,49=>110,
50=>111,51=>112,52=>113,53=>114,54=>115,55=>116,56=>117,57=>118,58=>119,
59=>120,60=>121,61=>122
);
public static function base62($int) {
$key = "";
while(bccomp($int, 0) > 0) {
$mod = bcmod($int, 62);
$key .= chr(self::$chars62[$mod]);
$int = bcdiv($int, 62);
}
return strrev($key);
}
public static function hash($num, $len = 5) {
$ceil = bcpow(62, $len);
$primes = array_keys(self::$golden_primes);
$prime = $primes[$len];
$dec = bcmod(bcmul($num, $prime), $ceil);
$hash = self::base62($dec);
return str_pad($hash, $len, "0", STR_PAD_LEFT);
}
public static function unbase62($key) {
$int = 0;
foreach(str_split(strrev($key)) as $i => $char) {
$dec = array_search(ord($char), self::$chars62);
$int = bcadd(bcmul($dec, bcpow(62, $i)), $int);
}
return $int;
}
public static function unhash($hash) {
$len = strlen($hash);
$ceil = bcpow(62, $len);
$mmiprimes = array_values(self::$golden_primes);
$mmi = $mmiprimes[$len];
$num = self::unbase62($hash);
$dec = bcmod(bcmul($num, $mmi), $ceil);
return $dec;
}
}
答案 2 :(得分：44)
URL缩短服务而不是使用自动递增的整数值（如补充数据库ID）并使用Base64或其他编码对其进行编码，以便每个字符有更多信息（64而不是仅仅10个像数字）。
答案 3 :(得分：17)
最短哈希是32个字符长度，你怎么能使用md5哈希的前8个字符
echo substr(md5('http://www.google.com'), 0, 8);
更新：这是另一个由here编写的Travell Perkins类，它接受记录号并为其创建短哈希。 14位数字产生8位数字符串。到达这个数字的那一天，你变得比tinyurl更受欢迎;）
class BaseIntEncoder {
//const $codeset = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
//readable character set excluded (0,O,1,l)
const codeset = "23456789abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";
static function encode($n){
$base = strlen(self::codeset);
$converted = '';
while ($n > 0) {
$converted = substr(self::codeset, bcmod($n,$base), 1) . $converted;
$n = self::bcFloor(bcdiv($n, $base));
}
return $converted ;
}
static function decode($code){
$base = strlen(self::codeset);
$c = '0';
for ($i = strlen($code); $i; $i--) {
$c = bcadd($c,bcmul(strpos(self::codeset, substr($code, (-1 * ( $i - strlen($code) )),1))
,bcpow($base,$i-1)));
}
return bcmul($c, 1, 0);
}
static private function bcFloor($x)
{
return bcmul($x, '1', 0);
}
static private function bcCeil($x)
{
$floor = bcFloor($x);
return bcadd($floor, ceil(bcsub($x, $floor)));
}
static private function bcRound($x)
{
$floor = bcFloor($x);
return bcadd($floor, round(bcsub($x, $floor)));
}
}
以下是如何使用它的示例：
BaseIntEncoder::encode('1122344523');//result:3IcjVE
BaseIntEncoder::decode('3IcjVE');//result:1122344523
答案 4 :(得分：4)
对于简短的hash， URL友好，鉴于不允许重复的内容，我们可以使用hash()，尤其是CRC哈希类型，因为它正是为此而设计的：
循环冗余检查
循环冗余校验（CRC）通常是一种错误检测代码 用于数字网络和存储设备以检测意外 更改原始数据。进入这些系统的数据块很短 根据多项式除法的余数附加检查值 他们的内容。在检索时，将重复计算，然后 如果检查值不匹配，则可以采取纠正措施
echo hash("crc32", "Content of article...");
// Output fd3e7c6e
答案 5 :(得分：1)
以下是代码：
<?php
/*
THE FOLLOWING CODE WILL PRINT:
A database_id value of 200 maps to 5K
A database_id value of 1 maps to 1
A database_id value of 1987645 maps to 16LOD
*/
$database_id = 200;
$base36value = dec2string($database_id, 36);
echo "A database_id value of $database_id maps to $base36value\n";
$database_id = 1;
$base36value = dec2string($database_id, 36);
echo "A database_id value of $database_id maps to $base36value\n";
$database_id = 1987645;
$base36value = dec2string($database_id, 36);
echo "A database_id value of $database_id maps to $base36value\n";
// HERE'S THE FUNCTION THAT DOES THE HEAVY LIFTING...
function dec2string ($decimal, $base)
// convert a decimal number into a string using $base
{
//DebugBreak();
global $error;
$string = null;
$base = (int)$base;
if ($base < 2 | $base > 36 | $base == 10) {
echo 'BASE must be in the range 2-9 or 11-36';
exit;
} // if
// maximum character string is 36 characters
$charset = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
// strip off excess characters (anything beyond $base)
$charset = substr($charset, 0, $base);
if (!ereg('(^[0-9]{1,50}$)', trim($decimal))) {
$error['dec_input'] = 'Value must be a positive integer with < 50 digits';
return false;
} // if
do {
// get remainder after dividing by BASE
$remainder = bcmod($decimal, $base);
$char = substr($charset, $remainder, 1); // get CHAR from array
$string = "$char$string"; // prepend to output
//$decimal = ($decimal - $remainder) / $base;
$decimal = bcdiv(bcsub($decimal, $remainder), $base);
} while ($decimal > 0);
return $string;
}
?>
答案 6 :(得分：0)
实际上，具有“随机”哈希的最佳解决方案是生成随机哈希列表，将其放在具有唯一INDEX的Mysql上（您可以编写一个简单的UDF以在1个seconde中插入100 000行）。
我认为像这样的结构ID | HASH | STATUS | URL | VIEWS | ......
其中status表示此Hash是否空闲。
答案 7 :(得分：0)
在数据库中重复检查的简便方法：
$unique = false;
// While will be repeated until we get unique hash
while($unique == false) {
// Getting full hash based on random numbers
$full_hash = base64_encode( rand(9999,999999) );
// Taking only first 8 symbols
$hash = substr($full_hash, 0, 8);
// Checking for duplicate in Database - Laravel SQL syntax
$duplicate = \App\Item::where('url', $hash)->count();
// If no Duplicate, setting Hash as unique
if ($duplicate==0) {
// For stoping while
$unique=true;
// New Hash is confirmed as unique
$input['url']=$hash;
}
}
答案 8 :(得分：0)
我正在简化网址。就我而言，我每次使用数据库的“ id”来创建唯一的短网址。
首先我要做的是-
在db中插入“原始url”和“创建日期”之类的数据，而在db中保留“短url”为空。 然后从那里获取“ id”并传递下面的函数。
<?php
function genUniqueCode($id){
$id = $id + 100000000000;
return base_convert($id, 10, 36);
}
//Get Unique Code using ID
/*
id Below is retrived from Database after Inserting Original URL.
*/
$data['id'] =10;
$uniqueCode = genUniqueCode($data['id']);
// Generating the URL
$protocol = strtolower(substr($_SERVER["SERVER_PROTOCOL"],0,5))=='https'?'https':'http';
echo "<a href='{$protocol}://{$_SERVER['HTTP_HOST']}/{$uniqueCode}'>{$protocol}://{$_SERVER['HTTP_HOST']}/{$uniqueCode}</a>";
?>
然后更新数据库中的短网址代码的值。
在这里，我使用“ id”来创建短代码。由于多个条目的ID不能相同。它是唯一的，因此唯一代码或网址将是唯一的。
答案 9 :(得分：0)
我写了某种算法。
是
<?php
class PseudoCrypt1
{
private static $keychars = 'CZPXD5H2FIWB81KE76JY93V4ORLAMT0QSUNG'; // Dictionary of allowed unique symbols, shuffle it for yourself or remove unwanted chars (don't forget to call testParameters after changing)
private static $divider = 19; // Tune divider for yourself (don't forget to call testParameters after changing)
private static $biasDivider = 14; // Tune bias divider for yourself (don't forget to call testParameters after changing)
private static $noise = 53; // Any positive number
public static function testParameters()
{
if (strlen(static::$keychars) < static::$divider + static::$biasDivider - 1) {
throw new Exception('Check your divider and biasDivider. It must be less than keychars length');
}
}
public static function encode(int $i): string
{
if ($i < 0) {
throw new Exception('Expected positive integer');
}
$keychars = static::$keychars;
$i = $i + static::$noise; // add noise to a number
$bias = $i % static::$biasDivider;
$res = '';
while ($i > 0) {
$div = $i % static::$divider;
$i = intdiv($i, static::$divider);
$res .= $keychars[$div + $bias];
}
// Current version of an algorithm is one of these chars (if in the future you will need to identify a version)
// Remember this chars on migrating to a new algorithm/parameters
$res .= str_shuffle('LPTKEZG')[0];
$res .= $keychars[$bias]; // Encoded bias
return $res;
}
public static function decode($code)
{
$keychars = static::$keychars;
$biasC = substr($code, -1);
$bias = strpos($keychars, $biasC);
$code = substr($code, 0, -2);
$code = str_split(strrev($code));
$val = 0;
foreach ($code as $c) {
$val *= static::$divider;
$val += strpos($keychars, $c) - $bias;
}
return $val - static::$noise;
}
}
输出
36926 -> 7IWFZX
927331 -> F4WIKP2
9021324 -> AT66R7P1
你可以用这个小测试来测试它（它不包括唯一性测试，但算法是唯一的）：
PseudoCrypt1::testParameters();
for ($i = 4000000; $i < 9500000; $i++) {
$hash = PseudoCrypt1::encode($i);
echo $i.':'.strlen($hash).':'.$hash.PHP_EOL;
if ($i != PseudoCrypt1::decode($hash)) {
echo 'FAIL:'.$i.PHP_EOL;
die();
}
}