Exemplo de código manual de criptografar e descriptografar strings em PHP.
<?php
$string = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789()/?><.,;:}]{[-_=+%$&*#@$!'" . '"';
function criptografar( $string ) {
$r = "";
for ( $i = 0; $i < strlen( $string ); $i++ ) {
$n = ord( $string[ $i ] ) * 2 + 1;
if ( $n < 10 ) {
$n = "00" . $n;
} elseif ( $n < 100 ) {
$n = "0" . $n;
}
$r .= base64_encode( chr( $n ) );
}
$r1 = "";
for ( $i = 0; $i < strlen( $r ); $i++ ) {
$c = $r[ $i ];
$n = ord( $c );
if ( $n < 10 ) {
$n = "00" . $n;
} elseif ( $n < 100 ) {
$n = "0" . $n;
}
$r1 .= $n;
}
return $r1;
}
function descriptografar( $string ) {
$r = "";
for ( $i = 0; $i < strlen( $string ) / 3; $i++ ) {
$c = chr( substr( $string, $i * 3, 3 ) );
$r .= $c;
}
$string = $r;
$r = "";
for ( $i = 0; $i < strlen( $string ) / 4; $i++ ) {
$n = ord( base64_decode( substr( $string, $i * 4, 4 ) ) );
$r .= chr( ( $n - 1 ) / 2 );
}
return $r;
}
$cript = criptografar( $string );
$dcript = descriptografar( $cript );
echo strlen( $cript ) . " - " . strlen( $string ) . " - ";
echo $cript . " - " . $dcript . "<br>";
?>