Increasing Confiedentiality

• A message from A to B could be encrypted as: [[M]KApriv]KBpub= M

• Decryption: [[M]KBpriv]KApub= M

• Where: [[[[M]KApriv]KBpub]KBpriv]KApub= M

• Wouldn't such a system be neat...

• (Not all asymmetric key cryptosystems have the propery: [[M]KBpriv]KBpub= M