The sovereignty of open-source projects must be protected. Open-source projects are the lifeblood of today's tech. The operating system upon which I am writing this is open-source, and so, if I wanted, I could edit it, or share it with you. The editor with which I edit this is open-source, and so, if I wanted, I could (and have) modified it or shared it. Why does this matter, I hear you ask? The main reason I want to focus on is:
Transparency and trust: You may be asking, "Wait, if the source code is open, what's stopping hackers from viewing the source code and figuring out all of the vulnerabilities?" Well, sadly there is nothing stopping hackers from viewing the source code. However, hiding the source code is a fundamentally insecure method of security. As the locksmith Alfred Hobbs once said in his book, The Construction of Locks and Safes,
Many well-meaning persons suppose that the discussion respecting the means for baffling the supposed safety of locks offers a premium for dishonesty, by shewing others how to be dishonest. This is a fallacy. Rogues are very keen in their profession, and know already much more than we can teach them (Hobbs 2)
Even today, the algorithms that protect everything from your Facebook posts to your bank transactions to the communications of the U.S. military are all public knowledge. Through opening our methods for all to see, we can get feedback on our methods from all. At the risk of being eclectic, I'd like to include a quote by Dutch cryptographer Auguste Kerckhoffs, from his essay in Le Journal de Sciences Militaires entitled La Cryptographie Militaire:
Il faut qu'il n'exige pas le secret, et qu'il puisse sans inconvénient tomber entre les mains de l'ennemi ([The cryptosystem] must not require secrecy, and it must not be a problem1 if it falls into enemy hands).
Another example of where an open system is better for security is the Tor Project. Originally created in the 90s by the U.S. Navy, it was meant as a way to communicate with the U.S. in situations in which being connected to a U.S. IP would compromise missions. In 2006, the government open-sourced it and releassed it as the Tor Project. It's in the interests of the military that it is used by civilians, because the thing about Tor traffic is that, as an ISP, the only thing you can tell about the traffic is the entry node to which the traffic is heading and that it is Tor traffic. Now, if only the military used Tor, the presence of Tor traffic would be a major red flag. Because, however, it's also used by dissidents, journalists, regular citizens, and (yes) criminals, the security of those missions is protected, somewhat ironically, by that transparency.
Footnotes:
A more faithful translation would be "it can, without disadvantage, fall into enemy hands".