Oefententamen Advising Countermeasurus
Question 1: The OSI model (14 points)
a) The OSI network model consists of 7 layers. The TCP-IP model has less
layers. Which layers of the OSI layer are the same as the Application layer
of the TCP-IP model?
(3 points)
Application, Presentation and Session Layer
b) Explain the functionality for each of these layers in question a. (6 points)
The application layer enables the user -- human or software -- to
interact with the application or network whenever the user elects
to read messages, transfer files or perform other network-related
tasks. Web browsers and other internet-connected apps, such as
Outlook and Skype, use Layer 7 application protocols.(2 points)
The presentation layer translates or formats data for the application layer based on the
semantics or syntax the application accepts. This layer also handles the encryption and
decryption that the application layer requires.(2 points)
The session layer sets up, coordinates and terminates
conversations between applications. Its services include
authentication and reconnection after an interruption. This layer
determines how long a system will wait for another application to
respond. (2 points)
c) Name for each of these layers a protocol which is commonly used within
these layers (3 points)
Application Layer: HTTP, FTP, DNS, SNMP, Telnet. (1 point )
Presentation Layer: SSL, TLS, MPEG JPEG (1 point)
Session Layer:API, Sockets, NetBios ( 1 point)
d) Which layer (name) use IP addressing to route date between networks (1
point)
Network Layer
e) Which layer (name) use MAC addressing to route data in a specific
network? (1 point)
Data Link Layer
Question 2: Encryption (10 points)
a) Explain what confidentiality service means in a data communication (2
points)
Confidentiality refers to protecting information from unauthorized
access.
b) Explain what non-repudiation service means in a data communication (2
points)
Nonrepudiation ensures that no party can deny that it sent or
received a message via encryption and/or digital signatures or
approved some information. It also cannot deny the authenticity of its
signature on a document.
c) Explain what authenticity service means in a data communication (2
points)
Authenticity validates the source or origin of data and other file
transfers through proof of identity. This is important because it
ensures that the message (email, payment transaction, digital file, etc.)
was not corrupted or intercepted during transmission.
d) If a data communication is encrypted with the sender’s private key, what
security service is (are) provided? Explain (2 points)
Authenticity of the sender and non-repudiation. If the receiver can
decrypt the encrypted data with the sender’s public key, the she
knows the data was encrypted with the senders private key.
e) If the sender’s data communication is encrypted with the receiver’s public
key, what security service is (are) provided? Explain (2 points)
Confidentiality, Only the person who has the private key can
decrypt it.
Question 1: The OSI model (14 points)
a) The OSI network model consists of 7 layers. The TCP-IP model has less
layers. Which layers of the OSI layer are the same as the Application layer
of the TCP-IP model?
(3 points)
Application, Presentation and Session Layer
b) Explain the functionality for each of these layers in question a. (6 points)
The application layer enables the user -- human or software -- to
interact with the application or network whenever the user elects
to read messages, transfer files or perform other network-related
tasks. Web browsers and other internet-connected apps, such as
Outlook and Skype, use Layer 7 application protocols.(2 points)
The presentation layer translates or formats data for the application layer based on the
semantics or syntax the application accepts. This layer also handles the encryption and
decryption that the application layer requires.(2 points)
The session layer sets up, coordinates and terminates
conversations between applications. Its services include
authentication and reconnection after an interruption. This layer
determines how long a system will wait for another application to
respond. (2 points)
c) Name for each of these layers a protocol which is commonly used within
these layers (3 points)
Application Layer: HTTP, FTP, DNS, SNMP, Telnet. (1 point )
Presentation Layer: SSL, TLS, MPEG JPEG (1 point)
Session Layer:API, Sockets, NetBios ( 1 point)
d) Which layer (name) use IP addressing to route date between networks (1
point)
Network Layer
e) Which layer (name) use MAC addressing to route data in a specific
network? (1 point)
Data Link Layer
Question 2: Encryption (10 points)
a) Explain what confidentiality service means in a data communication (2
points)
Confidentiality refers to protecting information from unauthorized
access.
b) Explain what non-repudiation service means in a data communication (2
points)
Nonrepudiation ensures that no party can deny that it sent or
received a message via encryption and/or digital signatures or
approved some information. It also cannot deny the authenticity of its
signature on a document.
c) Explain what authenticity service means in a data communication (2
points)
Authenticity validates the source or origin of data and other file
transfers through proof of identity. This is important because it
ensures that the message (email, payment transaction, digital file, etc.)
was not corrupted or intercepted during transmission.
d) If a data communication is encrypted with the sender’s private key, what
security service is (are) provided? Explain (2 points)
Authenticity of the sender and non-repudiation. If the receiver can
decrypt the encrypted data with the sender’s public key, the she
knows the data was encrypted with the senders private key.
e) If the sender’s data communication is encrypted with the receiver’s public
key, what security service is (are) provided? Explain (2 points)
Confidentiality, Only the person who has the private key can
decrypt it.
