I’ve been trying to get my head around this and I’ve watched a few videos but they don’t seem to specifically answer my question.
According to what I’ve found online, messages encrypted with a public key can only be decrypted with a private key. But in practice, how is that possible?
Surely a public key contains a set of instructions, and anyone could just run those instructions in reverse to decrypt a message? If everything you need to encrypt a message is stored within a public key, then how is it a one-way process?
It’s likely that I’m misunderstanding a core element of this!
Basically, asymmetric key cryptography is based on the idea that some algorithms are one-way roads. Or trap doors - falling down is easy, climbing up is much, much harder.
For a simple example, take adding numbers. I’ve got a thousand numbers, I add them up, and hand you the sum. Will you be able to find the thousand numbers I have from that sum? Probably not. The math involved in the actual cryptography is a bit more complex, but the principle holds.