// basic64加密算法等價php函數base64_encode()
function encode_base64($str)
{
$base64_alphabet = array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', '=');
$strlen = strlen($str);
for($i = 0; $i < $strlen; ++$i)
{
$asc = sprintf("%b", ord($str[$i]));
// 補0
$as_len = 8 - strlen($asc);
for($j = 0; $j < $as_len; ++$j) $asc = '0' . $asc;
$tmp1 .= $asc;
}
$len1 = $strlen * 8;
$residue = $len1 % 6;
if($residue)
$len2 = 6 - $len1 % 6;
else
$len2 = 0;
$len3 = ($len1 + $len2) / 6;
if($len2) $tmp1 .= $len2 > 2 ? '0000' : '00';
for($i = 0; $i < $len3; ++$i) $decode_str .= $base64_alphabet[bindec(substr($tmp1, $i * 6, 6))];
if($len2)
{
$decode_str .= $len2 > 2 ? '==' : '=';
}
return $decode_str;
}
// basic64解密算法等價php函數base64_decode()
function decode_base64($str)
{
$base64_alphabet = array('A' => 0, 'B' => 1, 'C' => 2, 'D' => 3, 'E' => 4, 'F' => 5, 'G' => 6, 'H' => 7,
'I' => 8, 'J' => 9, 'K' => 10, 'L' => 11, 'M' => 12, 'N' => 13, 'O' => 14, 'P' => 15,
'Q' => 16, 'R' => 17, 'S' => 18, 'T' => 19, 'U' => 20, 'V' => 21, 'W' => 22, 'X' => 23,
'Y' => 24, 'Z' => 25, 'a' => 26, 'b' => 27, 'c' => 28, 'd' => 29, 'e' => 30, 'f' => 31,
'g' => 32, 'h' => 33, 'i' => 34, 'j' => 35, 'k' => 36, 'l' => 37, 'm' => 38, 'n' => 39,
'o' => 40, 'p' => 41, 'q' => 42, 'r' => 43, 's' => 44, 't' => 45, 'u' => 46, 'v' => 47,
'w' => 48, 'x' => 49, 'y' => 50, 'z' => 51, '0' => 52, '1' => 53, '2' => 54, '3' => 55,
'4' => 56, '5' => 57, '6' => 58, '7' => 59, '8' => 60, '9' => 61, '+' => 62, '/' => 63, '=' => 64);
$strlen = strlen($str);
for($i = 0; $i < $strlen; ++$i)
{
if($str[$i] == '=') break;
else
{
if(!isset($base64_alphabet[$str[$i]]))
{
echo $str[$i] . ':傳入的加密字符串非法。';
exit();
}
$tmpstr = $base64_alphabet[$str[$i]];
$asc = sprintf("%b", $tmpstr);
}
$as_len = 6 - strlen($asc);
for($j = 0; $j < $as_len; ++$j) $asc = '0'.$asc;
$tmp1 .= $asc;
}
$len = ceil(strlen($tmp1) / 8);
for($i = 0; $i < $len; ++$i)
{
$decode_str .= chr(bindec(substr($tmp1, $i * 8, 8)));
}
return $decode_str;
}
字符串‘This is an encoded string’用第一個函數加密後得到‘VGhpcyBpcyBhbiBlbmNvZGVkIHN0cmluZw==’用第2個函數解密就可以回到‘This is an encoded string’。
他可以將任何字符串加密成只有字母和數字‘+’‘/’的組合,
呵呵,php裏有現成的函數我有註明。但自己寫的話,那是不一樣的。只要把函數裏的兩個$base64_alphabet數組對應打亂,並且引入新的符號,就可以得到自己特有的加密算法了,別人就不是那麼容易解你的密了。要更祕密可以用嵌套加密,而且每次加密的$base64_alphabet數組都不一樣。這樣的加密,你試試解碼給我看看!!!