backup security is the most valuable element of data backup. Trying to encrypt and backup your own data manually is tedious. Online backup security via software does the task automatically and uses the same process every time.
Open source backup systems online is risky. Existing systems (instead of open source) makes managing security automatic without the need to do any kind of re-configuring other than what the security within the software does and guarantees. A full online insurance guarantee is essential to online backup security therefore.
Open source software (cloud backup environment) can be a hassle because only those programming know what is going on.
Encryption Explained in general terms
AES - Advanced Encryption Standard
3DES - Triple Data Encryption Algorithm
SSL Explained by Wikipedia