Question

The confidentiality of the exchanged messages between users is not protected in most messaging systems. In most other words, they can read the messages you send to your friend through your service provider. In principle, before transmitting your message to the recipient the service provider can also change the content of your message.

Can you explain the public key encryption and private key encryption?

Using the Public key and private key, How does the sender, receiver and service provider communicate to send and receive messages?

The receiver can be disconnected and cannot receive messages, how can this situation be managed by your system?

Answer 1

Encrypting the message will help in maintaining the confidentiality of the exchanged messages between users. It is the process of encoding information to prevent anyone other than its intented receipt from viewing it. The encrypted information is unreadable to anyone who does not have access to a special key used to decrypt the information so that it’s readable.
Two modern methods of encryption are the Public Key (Asymmetric) and the Private Key (Symmetric) methods.
While these two methods of encryption are similar in that they both allow users to encrypt data to hide it from the prying eyes of outsiders and then decrypt it for viewing by an authorized party, they differ in how they perform the steps involved in the process.
1) Public Key Encryption
Public Key (Asymmetric) Encryption makes use of a recipient’s public key, along with a private key that mathematically matches the public key. A user can then send a message encrypted with the public key, which is then decrypted by the recipient, using their matching private key.

When using this encryption method, a sender can “unlock” a mailbox to place a message into it, but they would not be able to look at any of the other messages that may be in the mailbox, since the message can only be decrypted by using the recipient’s private key.
2) Private Key Encryption
The Private Key (Symmetric) Encryption method is similar to the Public Key method, as two keys are still required to encode and decode the information.
However, when using the Private Key Encryption method, both keys are basically the same. This means that both parties are allowed to encrypt and/or decrypt the information.

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Both methods make for efficient ways to protect messages and other information from viewing by those that have no business viewing your sensitive personal and business information.
The above two methods will help in encrypting the message that would prevent the utility company from knowing the content of the communications being exchanged.The service provider will not be able to read the encrypted message without the encryption key. If the receiver is online or available the sender can see their status in profile ensuring that they are available. After receiving the message by the receiver, the sender will be notified that message is received and seen by the user, thus ensuring that there is no manipulation between the sender and receiver maintaining the confidentiality of the exchanged messages.