source: sandbox/3.0/phpgwapi/inc/class.rsa.inc.php @ 2847

<?php


class rsa{

        var $e;
        var $d;
        var $n;

        function rsa(){
                session_start();
                if (!isset($_SESSION['phpgw_session']['publ_key']))
                {
                        $p=$this->genPrim();
                        $q=$this->genPrim();
                        $this->n=bcmul($p,$q);
                        $z=bcmul(bcsub($p,1),bcsub($q,1));
                        $this->d=$this->calc_d($z);
                        $this->e=$this->calc_e($this->d,$z);
                        $_SESSION['phpgw_session']['publ_key'] = $this->d;
                        $_SESSION['phpgw_session']['priv_key'] = $this->e;
                        $_SESSION['phpgw_session']['modulus'] = $this->n;
                }
                else
                {
                        $this->e = $_SESSION['phpgw_session']['publ_key'];
                        $this->d = $_SESSION['phpgw_session']['priv_key'];
                        $this->n = $_SESSION['phpgw_session']['modulus'] ;
                }
                session_write_close();
        }
        function encode($string){
                $result = "";
                for($i=0; $i < strlen($string); $i+=3)
                        $result .= $this->encode_(ord($string[$i]).ord($string[$i+1]).ord($string[$i+2]),$this->e,$this->n)." ";
                return $result;
        }
        function decode($string){
                $nums = split(" ",$string);
                foreach($nums as $todec)
                        if (ord($todec) > 1){
                                $num = $this->decode_($todec,$this->d,$this->n);
                                $num1 = substr($num,0,3);
                                $num2 = substr($num,3,3);
                                $num3 = substr($num,6,3);
                                ($num1 > 1) && $result .= chr($num1);
                                ($num2 > 1) && $result .= chr($num2);
                                ($num3 > 1) && $result .= chr($num3);

                        }
                return $result;
        }
        function get_publKey(){
                return $_SESSION['phpgw_session']['publ_key'];
        }
        function get_mod(){
                return $_SESSION['phpgw_session']['modulus'];
        }
        private function isPrime($Num){
                $result = true; 
                if($Num == 2 || $Num == 3)
                        return true;
                if($Num % 2 == 0)
                        return false;
                for($Divisor = 3; $Divisor < (sqrt($Num)+1); $Divisor+=2)
                {
                        $Res = $Num % $Divisor;
                        if($Res == 0)
                        {
                                $result=false;
                                break;
                        }
                }
                return $result;
        }

        private function genPrim(){
                $num=rand(100000,5000000);
                $i=$num;
                while($i++)
                        if ($this->isPrime($i))
                                return $i;
        }
        private function GCD($e,$m) {
                $y = $e;
                $x = $m;

                while (bccomp($y, 0) != 0) {
                        // modulus function
                        $w = bcsub($x, bcmul($y, bcdiv($x, $y, 0)));;
                        $x = $y;
                        $y = $w;
                }

                return $x;
        }

        //
        // Calculating E under conditions:
        // GCD(N,E) = 1 and 1<E<N
        //
        private function calc_d($m){
                $e = '3';
                if(bccomp($this->GCD($e, $m), '1') != 0){
                        $e = '5';
                        $step = '2';

                        while(bccomp($this->GCD($e, $m), '1') != 0){
                                $e = bcadd($e, $step);

                                if($step == '2'){
                                        $step = '4';
                                }else{
                                        $step = '2';
                                }
                        }
                }
                return $e;
        }
        private function calc_e ($Ee,$Em) {
                $u1 = '1';
                $u2 = '0';
                $u3 = $Em;
                $v1 = '0';
                $v2 = '1';
                $v3 = $Ee;

                while (bccomp($v3, 0) != 0) {
                        $qq = bcdiv($u3, $v3, 0);
                        $t1 = bcsub($u1, bcmul($qq, $v1));
                        $t2 = bcsub($u2, bcmul($qq, $v2));
                        $t3 = bcsub($u3, bcmul($qq, $v3));
                        $u1 = $v1;
                        $u2 = $v2;
                        $u3 = $v3;
                        $v1 = $t1;
                        $v2 = $t2;
                        $v3 = $t3;
                        $z  = '1';
                }

                $uu = $u1;
                $vv = $u2;

                if (bccomp($vv, 0) == -1) {
                        $inverse = bcadd($vv, $Em);
                } else {
                        $inverse = $vv;
                }

                return $inverse;
        }


        private function encode_($val,$e,$n){
                return bcpowmod($val,$e,$n);
        }
        private function decode_($val,$d,$n){
                return bcpowmod($val,$d,$n);
        }

}

?>