Networking

TABLE OF CONTENT

Introduction 3

Message sending process? 3

Receive message and decrypt 3

Protocol - what the protocol are designed to achieve 4

IMAP 4

POP3 4

SMTP 4

HTTP 4

Hardware/Software 4

Hardware 4

Software 4

Application, Network, and Transport protocols used 6

Transport Protocol 6

Encryption/Decryption process 6

Sending Public-Key Encrypted Mail 6

Receiving Public-Key Encrypted Mail 7

Why the Integrity of the Public Key is Essential 7

Conclusion 7

Reference: 8

Introduction

Ulysses (user) - sends email and attachment using private key encryption to send it from LAN to LAN.From the user standpoint, email seems so simple. You select the address of the person to whom you want to send the email, compose your message and click 'Send'. All done

In reality, sending your message off into the network cloud is a bit like sending Little Red Riding Hood into the deep dark woods. You never know what might happen.

Ulysses sends an email and an image which classes as an attachment to the email, when sending the email the user uses private key encryption to send the email to another user. A private key is used for generating digital signatures and for decrypting data. Also use for authentication, data encryption/decryption, digital signing, and secure e-mail.

Message sending process?

Once user sends the email here is how the progress to the end user?.

Your Internet Service Provider has a special computer called mail server, which is responsible for collecting mail from their customers. When you click the send button, your computer connects to the mail server and transmits the message along with the list of recipients.

The message is transmitted with Simple Mail Transfer Protocol (SMTP). SMTP is a language that your mail program uses to speak to the mail server. SMTP lets your mail program specify the list of recipients and the text of the message. Your destination recipient also has an Internet Service Provider. They have a mail server too.

When your SMTP server decides that it's time to send your email, it connects to the destination mail server and transmits the message to it. They use SMTP to speak to each other. Therefore the destination mail server is frequently called Destination SMTP Server.

When the recipient decides to check the email, his email program connects to the destination SMTP server and retrieves mail from the server. This time, they use Post Office Protocol Version 3 (POP3), which is a language used to receive mail. Therefore, this server is usually called Incoming POP3 Server. - Messages are send thought port TCP port 25

Receive message and decrypt

Once the user receives the mail it’s only the valid user can view the message. Also to make sure the message it legit and say who it’s from using the digital signature, the end user will use the public key to decrypt the message.

User opens his email program and receives the mail, his email program sends a request through Internet connection to Pop3 server (through TCP port 110) and downloads the message to his computer where he sees the message from sender.

Protocol - what the protocol are designed to achieve

The following email protocols are used to send and receive email messages: -

IMAP - Internet Message Access Protocol- using this email client can not only retrieve email but view it and manipulate it on the server as well.

POP3 – This is a local email client, so can be used to send and retrieve Ulysses message from a remote server connected to the internet that adopts the TCP/IP protocol. Here the format in which it sends and receives data will be decided, the