Trapping Global Keyboard Events Using Carbon

I came across the question "How do I trap keyboard events in kernel space", I answered this question with a question, why do you need to trap keyboard events in kernel space?...You don't, most of the time. The person then proceeded to tell me he didn't want to have to deal with a Graphical User Interface (gui) and so I thought ok i'll just google "trap key events without a gui mac os x" for him since he probably just skipped that part. Turns out there isn't a guide on creating an application that traps global keyboard events without using a graphical user interface. However it is very possible so I decided to write one.
since this is for tutorial purposes assume that all of this is in main.m (or .c) , also this will only compile properly under an i386 architecture because carbon event loops aren't support by 64 bit archs yet...go figure.
Post a comment with any questions

// *This code is meant to be for tutorial purposes*

#import <Carbon/Carbon.h>

//our callback for the event this is called every time 'your' event happens

OSStatus keyHandler(EventHandlerCallRef nextHandler, EventRef anEvent, void *userData){

printf("Hey! I trapped a global key event\n");

return noErr;

}

//register interest in the events you would like to receive notifications about

void setupEventHandler(){

EventHotKeyRef hotKeyRef;

EventHotKeyID hotKeyID;

EventTypeSpec eventType;

eventType.eventClass = kEventClassKeyboard;

eventType.eventKind = kEventHotKeyPressed;

InstallEventHandler(GetApplicationEventTarget(),

                                            &keyHandler,

                                                      1,

                                             &eventType,

                                                   NULL,

                                                   NULL);

hotKeyID.signature = '1';

hotKeyID.id = 1;

        RegisterEventHotKey(123,

                      optionKey,

                       hotKeyID,

     GetApplicationEventTarget(),

                               0,

                     &hotKeyRef);

}

int main (int argc, const char * argv[]) {

setupEventHandler();

RunApplicationEventLoop();

    

return 0;

}

How to save a headache using Jeff LaMarche's NSData-AES category

So after about 30 or so minutes of trying to figure why I could not get my data to decrypt properly after I encrypted it I came across a post by someone finding relief to this problem by changing the encryption keybits to 128 (located in the NSData-AES category *.h file) which did end up doing the trick....sort of, my data had a trailing tail of <202020 202020 202020 202020> which is...you guessed it, whitespace. This was very irritating because as I'm sure you can imagine comparing data with trailing whitespace does not yield nice results. So here is a solution I wrote. There may be more elegant ways to do this but this works for now.

NSData * encryptedData; 
NSString * trimString;
NSData * decryptedData;

encryptedData = [self returnSomeEncryptedDataUsingAPassword:@"password"];
decryptedData = [encryptedData AESDecryptWithAPassphrase:@"password"];
trimString = [[NSString alloc]initWithData:decryptedData
                                                     encoding:NSASCIIStringEncoding];
[trimString autorelease]; 
trimString = [trimString stringByTrimmingCharactersInSet:[NSCharacterSet whiteSpaceCharacterSet]]; 
decryptedData = [trimString dataUsingEncoding:NSASCIIStringEncoding];






There are of course variations to this for example you could use a temp string opposed to autoreleasing the trim string or instead of creating your own character set you could also use [NSCharacterSet whiteSpaceAndNewlineCharacterSet]; but for this we don't need new lines in the mix




Here is a link to the AES Catergories (NSFileManager works with 256 bit encryption)
http://iphonedevelopment.blogspot.com/2009/02/strong-encryption-for-cocoa-cocoa-touch.html