- (void) backgroundCreateKeyPair{
    @try {
        // 키 생성을 요청하고 그 결과값을 가져온다.
        NSString* result = @"";
        if([_opSignService createKeyPair])
            result = KEY_CREATION_SUCCESS;
        else
            result = KEY_CREATION_FAIL;

        [self performSelectorOnMainThread:@selector(foregroundCreateKeyPairResult:)
                               withObject:result
                            waitUntilDone:NO];

    } @catch (NSException *exception) {
        [self performSelectorOnMainThread:@selector(foregroundCreateKeyPairResult:)
                               withObject:KEY_CREATION_FAIL
                            waitUntilDone:NO];

        // 오류가 났을 경우 Popup화면을 띄워준다.
        [self performSelectorOnMainThread:@selector(foregroundCreateKeyPairException:)
                               withObject:exception
                            waitUntilDone:NO];
    } @finally {

    }
}