php中生成随机字符串的函数_PHP教程

function encrypt_str( $TXT, $KEY )
{
srand( ( double )microtime( ) * 1000000 );
$ENCRYPT_KEY = md5( rand( 0, 32000 ) );
$CTR = 0;
$TMP = "";
$I = 0;
for ( ; $I < strlen( $TXT ); ++$I )
{
if ( $CTR == strlen( $ENCRYPT_KEY ) )
{
$CTR = 0;
}
$TMP .= substr( $ENCRYPT_KEY, $CTR, 1 ).( substr( $TXT, $I, 1 ) ^ substr( $ENCRYPT_KEY, $CTR, 1 ) );
++$CTR;
}
return keyed_str( $TMP, $KEY );
}

function decrypt_str( $TXT, $KEY )
{
$TXT = keyed_str( $TXT, $KEY );
$TMP = "";
$I = 0;
for ( ; $I < strlen( $TXT ); ++$I )
{
$MD5 = substr( $TXT, $I, 1 );
++$I;
$TMP .= substr( $TXT, $I, 1 ) ^ $MD5;
}
return $TMP;
}

function keyed_str( $TXT, $ENCRYPT_KEY )
{
$ENCRYPT_KEY = md5( $ENCRYPT_KEY );
$CTR = 0;
$TMP = "";
$I = 0;
for ( ; $I < strlen( $TXT ); ++$I )
{
if ( $CTR == strlen( $ENCRYPT_KEY ) )
{
$CTR = 0;
}
$TMP .= substr( $TXT, $I, 1 ) ^ substr( $ENCRYPT_KEY, $CTR, 1 );
++$CTR;
}
return $TMP;
}