Public Key Cryptography
Public key cryptography for signing, in brief:
You posses your own public/private cryptographic key pair.
You publicly share your public key.
You sign a message with your private key.
Others verify the signature using your public key.
This proves the message came from you and hasn’t been altered.
Strong cryptography is hard to defeat (that's why Bitcoin works).
Our use:
Identity Layer (Your public key is your identity; you vouch for other folks' identities by signing statements refrencing their public keys)
Delegate Keys (You create and give other services disposable public/private key pairs and use your private identity key to sign a statement that that key pair represents you on that service)