system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can encryption methods be open source?

I was reading about the signal protocol and saw it has a github page. Doesn't this mean anyone can figure out how the encryption works and break it?
gpt
It is a generally accepted security precept that "The enemy knows the system." That is, when you are designing an encryption algorithm (or any security measure) that you assume the enemy knows its design. You assume that, eventually, an adversary will get a hold of the algorithm and therefore A) you cannot rely on the secrecy of the algorithm for security; and B) your algorithm should be secure despite general awareness of it.

The strength of encryption methods lies in the keys (and, for asymmetric methods, the inherent mathematical difficulty of reversing the encryption process).

For example, the most secure encryption method, the One Time Pad (OTP) has an extremely simplistic algorithm. ALL of the security is invested in how the key is created, used, and kept secret.