The signature proves that the message has the property of authenticity – that is, anyone with our public key (which is published publicly) can prove (with math) that only someone with the private key (which is kept very well-protected and only I have access-to) was able to sign the enclosed message.

How can you prove that I’m not lying? That’s a social problem. It’s not solved by technology; it’s solved with reputation.

I think I’ve demonstrated my commitment to my community, but ultimately you have to decide if you trust me.

It means we can authentically say that we have not been served an NSL to install backdoors into our software or hardware. Here’s two historical examples of this happening:

1. https://en.wikipedia.org/wiki/Lavabit#Suspension_and_gag_order
2. https://en.wikipedia.org/wiki/Doe_v._Gonzales

A warrant canary is a mechanism to let our users know that we may have been served an NSL and forced to install backdoors into our software or hardware.