> Asymmetric crypto and dozens of other schemes are used to fix those issues. I wouldn't say "fix" them, they replace them with easier to follow protocols whic

> Asymmetric crypto and dozens of other schemes are used to fix those issues. I wouldn't say "fix" them, they replace them with easier to follow protocols which have their own issues. But the security of all crypto boils down to following protocols. When someone introduces new cryptographic techniques, the advantages of those techniques (if any) are that easier protocols need to be followed. But there is always some protocol that must be followed, the crypto isn't going to let you levitate on air and secure a message just because of an algorithm. So deep scrutiny must be paid to the new protocols required to make the new tech secure. Just saying "problem X is solved" without figuring out what the replacement problem is will lead to disaster. E.g. Suppose you have two people that need to exchange messages. A) Without any crypto, they need to make sure no one intercepts any of the messages. So your protocol relies on "make sure no one intercepts a message and you authenticate the sender". B) With a symmetric key, protocol A is replaced with "make sure no one intercepts the first message and you authenticate the sender". C) With a public key, say using Diffie-Hellman, protocol B is replaced with "make sure no alters the first message and you authenticate the sender" D) With a certificate authority, protocol C is replaced with "Make sure you authenticate that the right certificate authority signed every message and you check the hostname" E) With a web of trust, protocol D is replaced by "make sure there is a quorum of signers you already trust that authenticate the identity of the sender". So a new tech is adopted when the protocols it follows are easier to enforce than the protocols followed by the previous tech. But it never just "solves" the problem of needing to follow the protocols of the earlier tech. It is lack of awareness of this that led to many people being surprised about what happens when a rogue CA signs a message. Because they were too busy popping champagne corks to celebrate retiring protocol C that they forgot to worry about correctly enforcing protocol D.