function alphaID($in, $to_num = false, $pad_up = false, $pass_key = null) { $out = ''; $index = 'abcdefghijklmnopqrstuvwxyz0123456789'; $base = strlen($index); if ($pass_key !== null) { for ($n = 0; $n < strlen($index); $n++) { $i[] = substr($index, $n, 1); } $pass_hash = hash('sha256',$pass_key); $pass_hash = (strlen($pass_hash) < strlen($index) ? hash('sha512', $pass_key) : $pass_hash); for ($n = 0; $n < strlen($index); $n++) { $p[] = substr($pass_hash, $n, 1); } array_multisort($p, SORT_DESC, $i); $index = implode($i); } if ($to_num) { // Digital number <<-- alphabet letter code $len = strlen($in) - 1; for ($t = $len; $t >= 0; $t--) { $bcp = bcpow($base, $len - $t); $out = $out + strpos($index, substr($in, $t, 1)) * $bcp; } if (is_numeric($pad_up)) { $pad_up--; if ($pad_up > 0) { $out -= pow($base, $pad_up); } } } else { // Digital number -->> alphabet letter code if (is_numeric($pad_up)) { $pad_up--; if ($pad_up > 0) { $in += pow($base, $pad_up); } } for ($t = ($in != 0 ? floor(log($in, $base)) : 0); $t >= 0; $t--) { $bcp = bcpow($base, $t); $a = floor($in / $bcp) % $base; $out = $out . substr($index, $a, 1); $in = $in - ($a * $bcp); } } return $out; }
id可逆加密
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转载自mailx8.iteye.com/blog/2397700
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