Advance Computer Network (TCP and Security)

Topics:

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Submission:

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[login to view URL] and Applications (20 marks)

Authentication has long been a problem for transactions. How do you know if

someone presenting a card really is the owner of that card? Simple methods include

matching a signature to a previously signed one on the back or entering a PIN.

Now with PayWave, only authentication by possession (of the card) is required.

Currently, there are a number of initiatives to use mobile devices for the

functionality of payment. This raises the question of how safe are the devices and

what mechanisms are built in to prevent fraud. A number of platform vendors have

introduced electronic card payments to their devices. For example Apple

introduced ApplePay in iPhone and Apple Watch.

With reference to the techniques in the security lectures, examine how various

vendors approach secure payments. Is it easy to use for legitimate users while

difficult to crack for attackers? Does it provide confidentiality, integrity,

authentication, anti-replay, and non-repudiation? In what ways might these

transactions be compromised and how are they counteracted?

You should start with a general description of Apple Pay and another (Androidbased) service, an overview of how it works, and what encryption is used. Where is

encryption applied? Examine the authentication functions. What protocols are

used? Then evaluate it with reference to the previous paragraph. How do the

different vendor’s offerings compare? Where are they the same or similar, and how

do they differ?

Host A and B are communicating over a TCP connection, and Host B has already

received from A all bytes up to byte 126. Suppose Host A then sends two segments

to Host B back-to-back. The first and second segments contain 80 and 40 bytes of

data, respectively. In the first segment, the sequence number is 127, the source port

number is 3024, and the destination port number is 80. Host B sends an

acknowledgement whenever it receives a segment from Host A.

a. [5 marks] In the second segment sent from Host A to B, what are the sequence

number, source port number, and destination port number?

b. [5 marks] If the first segment arrives before the second segment, in the

acknowledgement of the first arriving segment, what is the acknowledgement

number, the source port number, and the destination port number?

c. [5 marks] If the second segment arrives before the first segment, in the

acknowledgement of the first arriving segment, what is the acknowledgement

number?

d. [10 marks] Suppose the two segments sent by A arrive in order at B. B sends

acknowledgements for both segments, but the first acknowledgement is lost and

the second acknowledgement arrives after the first timeout interval. Draw a

timing diagram showing these segments and all other segments and

acknowledgements sent (you can assume no other segment loss). For each

segment in your diagram, provide the sequence number and the number of

bytes of data; for each acknowledgement that you add, show the

acknowledgement number.

e. [5 marks] As we have seen, the Internet layer of TCP/IP has two protocols –

IPv4 and IPv6. The transport layer provides two main protocols TCP and UDP

(along with some special-purpose, minor protocols). But these are for very

different reasons. Why are the Internet and Transport layers very different in

providing two protocols?

f. [5 marks] Since UDP does very little that is different from IP, why do we even

have a transport layer such as UDP?

g. [5 marks] Describe how DDoS attacks may be mounted against TCP and UDP

services. In what way will being connection oriented be different for TCP and

UDP?

Clarity

Multi-paragraph answers should be structured into sections and subsections

with appropriate headings and subheadings.

Ambiguous or poorly worded answers will not be accepted

Spelling and grammar

spelling and grammar should be perfect for this task.

Bảo mật Internet Security Systems Payment Gateway Integration

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