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How can Alice have proof that Bob has received the message sent from Alice?
Assuming Alice signs the message using her private key and sends it to Bob, Bob can use Alice’s public key to verify the signature hence Alice cannot deny sending the message. This only proves that Alice is the sender of the message. How can Alice have proof that Bob has received the message sent from Alice?
How is an encrypted email sent to Alice?
Bob sends an encrypted email to Alice, with a symmetric key Kb. Alice and Bob then send each other the keys, bit by bit, one at a time. Either may bail out of the protocol at any time, with a partial key knowledge, and try to complete decryption through exhaustive search of the missing key bits.
How is encryption done in Alice and Bob?
This is how real world public-key encryption is often done. Bob generates a key pair, consisting of his public key (red padlock) and private key (red key). Bob then publishes his public key, and Alice fetches it (Bob mails his padlock to Alice).
How does Alice and Bob use the symmetric key?
Alice then generates a temporary symmetric key (the pair of orange keys) and uses Bob’s public key (red padlock) to securely send it to Bob. Bob then uses his private key (red key) to unlock his copy of the symmetric key (orange key). Bob and Alice can then use those symmetric keys to securely send messages back and forth.
Why does Bob want to know Alice’s private key?
Because Bob is the only one holding the private decryption key, he is also the only person that can decrypt the message. Bob wants to know for sure that the message he just received actually came from Alice. Alice keeps her encryption key private to encrypt the messages she sends.
What’s the story of Alice and Bob about?
This is a story about Alice and Bob. Alice wants to send a private message to Bob, and the only easy way they have to communicate is via postal mail. Unfortunately, Alice is pretty sure that the postman is reading the mail she sends.