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27-10-2013, 12:10 AM
حل واجب t325 اتصل 0544321455/00966544321455 ايميل [email protected] (http://www.aswaqcity.com/thread1310656.html)
حل واجبات الجامعة العربية المفتوحة
اتصل : O544321455 - OO966544321455
واتس اب: 966544321455+
ايميل : [email protected]
سكايبي : a_al_shora
حل واجب (http://www.aswaqcity.com/thread1310656.html) 0.5.4.4.3.2.1.4.5.5 الجامعة العربية المفتوحة
حل واجبات الجامعة العربية المفتوحة O54.4.3.2.1.4.5.5 - OO96654.4.3.2.1.4.5.5
ايميل : a_al_shora @ h.o.t.m.ail.c.o.m
سكايبي: a_al_shora
واتس اب: OO96654.4.3.2.1.4.5.5
T325: Technologies for digital media
__________________________________________________ ____________________________
Tutor-marked Assignment
__________________________________________________ ____________________________
T325: TMA, FALL 2013 Cut-off date: December 12, 2013
__________________________________________________ ____________________________
Total Marks: 100
Question 1 (This question carries 25% of the marks for this assignment)
Flexible displays are considered to be one of the most promising directions of the development of handheld devices. This has been confirmed with the announcements of a number of handheld devices manufacturers that they are developing smartphones with flexible displays; some of them even demonstrated some prototypes (e.g. Samsung, LG [1]).
Using the AOU e-library or any other Internet reliable resource, you are asked to prepare a short report about flexible displays for portable devices.
You report should include the following information:
a) Introduction about flexible displays (how they work). You are not asked to go into a deep technical level. Your answer should be suitable for a general IT audience. (12 marks)
b) Advanes of using flexible displays in handheld devices (at least three) (9 marks)
c) Main limitation(s) to use flexible displays in handheld devices (4 marks)
Your report should include these three sections in addition to a section that contains the references of your report. The references should be listed in a standard format and includes all the necessary information (Title, Author(s) (s), publication date, etc.). You can refer to the “References” section at the end of the TMA to have a clear idea on what kind of information should be provided for a reference. For further information, you can refer to the following link for more information: http://library.open.ac.uk/help/howto/citeref/).
Not listing the references of your work will be considered as a plagiarism act and will lead to the application of plagiarism penalty as per the AOU regulations.
In addition, the following mark deduction might be applied:
• Two marks for NOT listing the references in a standard format
• One mark for exceeding the word count limit (800 words)
Question 2 (This question carries 35% of the marks for this assignment)
You have seen in Block 1 – Part 5 that Huffman coding is used in the last step of the spatial encoding se of the MPEG coding process. In addition, it was mentioned that this code – in contrast with fixed length coding techniques such as run-length coding – is a variable-length coding technique. “Huffman coding uses short code words for the most commonly occurring patterns and longer words for those patterns that occur less frequently (rather as Morse uses short codes for commonly occurring letters and long ones for less common ones). This results in significant compression of the data without any loss of
information.” [2] However, you didn’t get the chance to see how this code works.
This exercise is a good opportunity to understand how this code works. We will start first by reading the Appendix A of this TMA which explain by example how to construct a Huffman tree for a given set of values (which can be numbers, letters or symbols) and how to encode these values.
Part I.
After reading this tutorial, you are asked to construct the Huffman tree for the sentence:
“**** ***** likes Huffman code”
(replace the stars with your first and your last e.g. Paul smith likes Huffman code)
Note that the space is considered as a character. This exercise is not case-sensitive (capital and small letters are considered the same, so the first step is to write the sentence in small letters).
You should detail the different steps of the construction of the Huffman tree:
a) Construction of the table of frequencies (5 marks)
b) The different steps of constructing the Huffman tree (15 marks) (You should detail each step, the final answer is not sufficient)
c) Reading the codes corresponding to each different letter in the sentence (5 marks)
d) Write the final code of the whole sentence (2 marks)
Part II.
a) As you know, ASCII code is a fixed-length coding scheme. Using the 7-bit ASCII code table [3], find the corresponding code for the sentence you have encoded in the first part. (5 marks)
b) Compare the total length of the encoded sentence using a variable-length (Huffman) and fixed-length (ASCII) coding schemes. What did you find? (3 marks)
Question 3 (This question carries 40% of the marks for this assignment)
This exercise is a good opportunity for you to practice the different theoretical cryptographic concepts you have seen in Block II – Part 2 (symmetric encryption, Asymmetric encryption, X.509 certificates, Certification authority).
We will be using the well-known OpenSSL cryptographic library and command line tool. This tool comes built-in in most Linux distributions. If you are a MS Windows user, you can download the command line tool from [4] or [6].
A good tutorial for using the basic OpenSSL command lines can be found in [5]. This tutorial is very useful to do the different parts of this question); if you are a MS Windows user, some UNIX commands – in this tutorial - such as cat, touch (which are not OpenSSL commands) will not work; you can instead use any file editor (notepad for instance) to display or edit files.
Using the OpenSSL command line tool and the -editing tool, you are asked to do the following:
1- Using any editing tool, create a file d info-****.txt (replace the stars in this part and in the rest of the question with your short ID) that contains four lines:
Your first and last
Your student short ID
Your Branch
Your section number
Symmetric encryption (7 marks)
2- Using OpenSSL command line tool, encrypt this file with the triple-DES symmetric algorithm. The output encrypted file should be d “info-****-3des.enc” (again the stars should be replaced with your short ID). The encryption password should be: “openssl” (in small letters) (3 marks)
3- Using OpenSSL command line tool, decrypt the encrypted file (the result of the previous step) using the same algorithm and password.
The output encrypted file should be d “info-****-dec-3des.txt”. (3 marks)
4- Verify the of your decrypted file using any -editing tool. (1 marks)
Public Keys
Key generation (12 marks)
5- Generate an RSA private key of 2048 bits. The private key file should be d “rsa-****-private-2048.key” (2 marks)
6- Using any editor , display the of the file rsa-****-private-2048.key. In which format the key is written in this file? Briefly explain this format. (3 marks)
7- Display the details of the RSA key (generated in step 5). (2 marks)
8- Encrypt this key (in order to protect it) using the tripleDES algorithm using a password (use “openssl” as a password). The output file (encrypted key) should be d
“rsa-****-private-2048-enc.key” (3 marks)
9- Extract the public key - from the private key - in a separate file. The public key file should be d: “rsa-****-public-2048.key” (2 marks)
Encryption (6 marks)
10- Encrypt the file generated in 1 using your public key (extracted in 9). The output file should be d “info-****-rsa.enc (3 marks)
11- Decrypt the encrypted file (in 10) using your private key. The output file should be d “info-****-dec-rsa.txt” (3 marks)
Digital signature (6 marks)
12- Sign the file that you created in part 1 using your private key. As you know, digital signature is calculated d on the message digest of the file to sign. However, in our case, we will sign the file directly (since the size of the file is too small). The signed file should be d:
“info-****-sign-rsa.txt” (3 marks)
13- Verify the signature of the file obtained in (11) using your public key (extracted in 9) (3 marks)
Public Key Infrastructure (9 marks)
14- In this part, you are asked to create a certification authority and generate a X509 certificate for the keys you have generated in part 5.
a. First you have to create a pair of 2048-bits RSA keys for the certification authority (CA). Then create a self-signed certificate for the certification authority. You should specify the Common (CN) of the CA as “AOU” and the email of the CA as [email protected]. The self signed certificate should be d “CA-cert-****.pem”.
(MS Windows users might need to explicitly indicate the path for the openssl.cnf file (using the option –config) in the command line in order to be able to use PKI commands) (3 marks)
b. Do the necessary modification to the OpenSSL configuration file (refer to the OpenSSL tutorial) in order to be able to use the CA certificate file for certificate generation. Explain these modifications. (2 marks)
c. Create a certificate request (d req-****.pem) for the private key that you have generated in part 5 (2 marks)
d. Sign the certificate request using the CA self-signed certificate file. The certificate file should be d “cert-****.pem”. (2 marks)
Note: you can convert the generated certificate file in the binary format (DER format) in order to be able to include it in your browser or display its using MS windows built-in viewer). You can use the command : openssl x509 -in cert-****.pem -outform DER -out cert-****.der
Double click on the cert-****.der to view the of the certificate
The deliverable of this question are:
• A screenshot (whether for the command line or for the editor to show the of the files) of each part of the question that clearly shows the command used and the output of this command. The screenshot should be clear and at the same time you should not use a very high resolution in order to keep the size of the TMA file reasonable.
• A Zip file d *****-TMA-Q3 that contains all the files generated in the different parts of the question. This file will be uploaded to the Moodle Upload in addition to the TMA file.
Appendix: A quick tutorial on generating a Huffman tree
Let’s say you have a set of numbers and their frequency of use and want to create a Huffman encoding for them:
FREQUENCY VALUE
--------- -----
5 1
7 2
10 3
15 4
20 5
45 6
Creating a Huffman tree is simple. Sort this list by frequency and make the two-lowest elements into leaves, creating a parent node with a frequency that is the sum of the two lower element's frequencies:
12:*
/ \
5:1 7:2
The two elements are removed from the list and the new parent node, with frequency 12, is inserted into the list by frequency. So now the list, sorted by frequency, is:
10:3
12:*
15:4
20:5
45:6
You then repeat the loop, combining the two lowest elements. This results in:
22:*
/ \
10:3 12:*
/ \
5:1 7:2
and the list is now:
15:4
20:5
22:*
45:6
You repeat until there is only one element left in the list.
35:*
/ \
15:4 20:5
22:*
35:*
45:6
57:*
___/ \___
/ \
22:* 35:*
/ \ / \
10:3 12:* 15:4 20:5
/ \
5:1 7:2
45:6
57:*
102:*
__________________/ \__
/ \
57:* 45:6
___/ \___
/ \
22:* 35:*
/ \ / \
10:3 12:* 15:4 20:5
/ \
5:1 7:2
Now the list is just one element containing 102:*, you are done.
This element becomes the root of your binary Huffman tree. To generate a Huffman code you traverse the tree to the value you want, outputting a 0 every time you take a left-hand branch, and a 1 every time you take a right-hand branch. (Normally you traverse the tree backwards from the code you want and build the binary Huffman encoding string backwards as well, since the first bit must start from the top).
Example: The encoding for the value 4 (15:4) is 010. The encoding for the value 6 (45:6) is 1
Decoding a Huffman encoding is just as easy: as you read bits in from your input stream you traverse the tree beginning at the root, taking the left hand path if you read a 0 and the right hand path if you read a 1. When you hit a leaf, you have found the code.
Generally, any Huffman compression scheme also requires the Huffman tree to be written out as part of the file, otherwise the reader cannot decode the data. For a static tree, you don't have to do this since the tree is known and fixed.
حل واجبات الجامعة العربية المفتوحة
اتصل : O544321455 - OO966544321455
واتس اب: 966544321455+
ايميل : [email protected]
سكايبي : a_al_shora
حل واجب (http://www.aswaqcity.com/thread1310656.html) 0.5.4.4.3.2.1.4.5.5 الجامعة العربية المفتوحة
حل واجبات الجامعة العربية المفتوحة O54.4.3.2.1.4.5.5 - OO96654.4.3.2.1.4.5.5
ايميل : a_al_shora @ h.o.t.m.ail.c.o.m
سكايبي: a_al_shora
واتس اب: OO96654.4.3.2.1.4.5.5
حل واجبات الجامعة العربية المفتوحة
اتصل : O544321455 - OO966544321455
واتس اب: 966544321455+
ايميل : [email protected]
سكايبي : a_al_shora
حل واجب (http://www.aswaqcity.com/thread1310656.html) 0.5.4.4.3.2.1.4.5.5 الجامعة العربية المفتوحة
حل واجبات الجامعة العربية المفتوحة O54.4.3.2.1.4.5.5 - OO96654.4.3.2.1.4.5.5
ايميل : a_al_shora @ h.o.t.m.ail.c.o.m
سكايبي: a_al_shora
واتس اب: OO96654.4.3.2.1.4.5.5
T325: Technologies for digital media
__________________________________________________ ____________________________
Tutor-marked Assignment
__________________________________________________ ____________________________
T325: TMA, FALL 2013 Cut-off date: December 12, 2013
__________________________________________________ ____________________________
Total Marks: 100
Question 1 (This question carries 25% of the marks for this assignment)
Flexible displays are considered to be one of the most promising directions of the development of handheld devices. This has been confirmed with the announcements of a number of handheld devices manufacturers that they are developing smartphones with flexible displays; some of them even demonstrated some prototypes (e.g. Samsung, LG [1]).
Using the AOU e-library or any other Internet reliable resource, you are asked to prepare a short report about flexible displays for portable devices.
You report should include the following information:
a) Introduction about flexible displays (how they work). You are not asked to go into a deep technical level. Your answer should be suitable for a general IT audience. (12 marks)
b) Advanes of using flexible displays in handheld devices (at least three) (9 marks)
c) Main limitation(s) to use flexible displays in handheld devices (4 marks)
Your report should include these three sections in addition to a section that contains the references of your report. The references should be listed in a standard format and includes all the necessary information (Title, Author(s) (s), publication date, etc.). You can refer to the “References” section at the end of the TMA to have a clear idea on what kind of information should be provided for a reference. For further information, you can refer to the following link for more information: http://library.open.ac.uk/help/howto/citeref/).
Not listing the references of your work will be considered as a plagiarism act and will lead to the application of plagiarism penalty as per the AOU regulations.
In addition, the following mark deduction might be applied:
• Two marks for NOT listing the references in a standard format
• One mark for exceeding the word count limit (800 words)
Question 2 (This question carries 35% of the marks for this assignment)
You have seen in Block 1 – Part 5 that Huffman coding is used in the last step of the spatial encoding se of the MPEG coding process. In addition, it was mentioned that this code – in contrast with fixed length coding techniques such as run-length coding – is a variable-length coding technique. “Huffman coding uses short code words for the most commonly occurring patterns and longer words for those patterns that occur less frequently (rather as Morse uses short codes for commonly occurring letters and long ones for less common ones). This results in significant compression of the data without any loss of
information.” [2] However, you didn’t get the chance to see how this code works.
This exercise is a good opportunity to understand how this code works. We will start first by reading the Appendix A of this TMA which explain by example how to construct a Huffman tree for a given set of values (which can be numbers, letters or symbols) and how to encode these values.
Part I.
After reading this tutorial, you are asked to construct the Huffman tree for the sentence:
“**** ***** likes Huffman code”
(replace the stars with your first and your last e.g. Paul smith likes Huffman code)
Note that the space is considered as a character. This exercise is not case-sensitive (capital and small letters are considered the same, so the first step is to write the sentence in small letters).
You should detail the different steps of the construction of the Huffman tree:
a) Construction of the table of frequencies (5 marks)
b) The different steps of constructing the Huffman tree (15 marks) (You should detail each step, the final answer is not sufficient)
c) Reading the codes corresponding to each different letter in the sentence (5 marks)
d) Write the final code of the whole sentence (2 marks)
Part II.
a) As you know, ASCII code is a fixed-length coding scheme. Using the 7-bit ASCII code table [3], find the corresponding code for the sentence you have encoded in the first part. (5 marks)
b) Compare the total length of the encoded sentence using a variable-length (Huffman) and fixed-length (ASCII) coding schemes. What did you find? (3 marks)
Question 3 (This question carries 40% of the marks for this assignment)
This exercise is a good opportunity for you to practice the different theoretical cryptographic concepts you have seen in Block II – Part 2 (symmetric encryption, Asymmetric encryption, X.509 certificates, Certification authority).
We will be using the well-known OpenSSL cryptographic library and command line tool. This tool comes built-in in most Linux distributions. If you are a MS Windows user, you can download the command line tool from [4] or [6].
A good tutorial for using the basic OpenSSL command lines can be found in [5]. This tutorial is very useful to do the different parts of this question); if you are a MS Windows user, some UNIX commands – in this tutorial - such as cat, touch (which are not OpenSSL commands) will not work; you can instead use any file editor (notepad for instance) to display or edit files.
Using the OpenSSL command line tool and the -editing tool, you are asked to do the following:
1- Using any editing tool, create a file d info-****.txt (replace the stars in this part and in the rest of the question with your short ID) that contains four lines:
Your first and last
Your student short ID
Your Branch
Your section number
Symmetric encryption (7 marks)
2- Using OpenSSL command line tool, encrypt this file with the triple-DES symmetric algorithm. The output encrypted file should be d “info-****-3des.enc” (again the stars should be replaced with your short ID). The encryption password should be: “openssl” (in small letters) (3 marks)
3- Using OpenSSL command line tool, decrypt the encrypted file (the result of the previous step) using the same algorithm and password.
The output encrypted file should be d “info-****-dec-3des.txt”. (3 marks)
4- Verify the of your decrypted file using any -editing tool. (1 marks)
Public Keys
Key generation (12 marks)
5- Generate an RSA private key of 2048 bits. The private key file should be d “rsa-****-private-2048.key” (2 marks)
6- Using any editor , display the of the file rsa-****-private-2048.key. In which format the key is written in this file? Briefly explain this format. (3 marks)
7- Display the details of the RSA key (generated in step 5). (2 marks)
8- Encrypt this key (in order to protect it) using the tripleDES algorithm using a password (use “openssl” as a password). The output file (encrypted key) should be d
“rsa-****-private-2048-enc.key” (3 marks)
9- Extract the public key - from the private key - in a separate file. The public key file should be d: “rsa-****-public-2048.key” (2 marks)
Encryption (6 marks)
10- Encrypt the file generated in 1 using your public key (extracted in 9). The output file should be d “info-****-rsa.enc (3 marks)
11- Decrypt the encrypted file (in 10) using your private key. The output file should be d “info-****-dec-rsa.txt” (3 marks)
Digital signature (6 marks)
12- Sign the file that you created in part 1 using your private key. As you know, digital signature is calculated d on the message digest of the file to sign. However, in our case, we will sign the file directly (since the size of the file is too small). The signed file should be d:
“info-****-sign-rsa.txt” (3 marks)
13- Verify the signature of the file obtained in (11) using your public key (extracted in 9) (3 marks)
Public Key Infrastructure (9 marks)
14- In this part, you are asked to create a certification authority and generate a X509 certificate for the keys you have generated in part 5.
a. First you have to create a pair of 2048-bits RSA keys for the certification authority (CA). Then create a self-signed certificate for the certification authority. You should specify the Common (CN) of the CA as “AOU” and the email of the CA as [email protected]. The self signed certificate should be d “CA-cert-****.pem”.
(MS Windows users might need to explicitly indicate the path for the openssl.cnf file (using the option –config) in the command line in order to be able to use PKI commands) (3 marks)
b. Do the necessary modification to the OpenSSL configuration file (refer to the OpenSSL tutorial) in order to be able to use the CA certificate file for certificate generation. Explain these modifications. (2 marks)
c. Create a certificate request (d req-****.pem) for the private key that you have generated in part 5 (2 marks)
d. Sign the certificate request using the CA self-signed certificate file. The certificate file should be d “cert-****.pem”. (2 marks)
Note: you can convert the generated certificate file in the binary format (DER format) in order to be able to include it in your browser or display its using MS windows built-in viewer). You can use the command : openssl x509 -in cert-****.pem -outform DER -out cert-****.der
Double click on the cert-****.der to view the of the certificate
The deliverable of this question are:
• A screenshot (whether for the command line or for the editor to show the of the files) of each part of the question that clearly shows the command used and the output of this command. The screenshot should be clear and at the same time you should not use a very high resolution in order to keep the size of the TMA file reasonable.
• A Zip file d *****-TMA-Q3 that contains all the files generated in the different parts of the question. This file will be uploaded to the Moodle Upload in addition to the TMA file.
Appendix: A quick tutorial on generating a Huffman tree
Let’s say you have a set of numbers and their frequency of use and want to create a Huffman encoding for them:
FREQUENCY VALUE
--------- -----
5 1
7 2
10 3
15 4
20 5
45 6
Creating a Huffman tree is simple. Sort this list by frequency and make the two-lowest elements into leaves, creating a parent node with a frequency that is the sum of the two lower element's frequencies:
12:*
/ \
5:1 7:2
The two elements are removed from the list and the new parent node, with frequency 12, is inserted into the list by frequency. So now the list, sorted by frequency, is:
10:3
12:*
15:4
20:5
45:6
You then repeat the loop, combining the two lowest elements. This results in:
22:*
/ \
10:3 12:*
/ \
5:1 7:2
and the list is now:
15:4
20:5
22:*
45:6
You repeat until there is only one element left in the list.
35:*
/ \
15:4 20:5
22:*
35:*
45:6
57:*
___/ \___
/ \
22:* 35:*
/ \ / \
10:3 12:* 15:4 20:5
/ \
5:1 7:2
45:6
57:*
102:*
__________________/ \__
/ \
57:* 45:6
___/ \___
/ \
22:* 35:*
/ \ / \
10:3 12:* 15:4 20:5
/ \
5:1 7:2
Now the list is just one element containing 102:*, you are done.
This element becomes the root of your binary Huffman tree. To generate a Huffman code you traverse the tree to the value you want, outputting a 0 every time you take a left-hand branch, and a 1 every time you take a right-hand branch. (Normally you traverse the tree backwards from the code you want and build the binary Huffman encoding string backwards as well, since the first bit must start from the top).
Example: The encoding for the value 4 (15:4) is 010. The encoding for the value 6 (45:6) is 1
Decoding a Huffman encoding is just as easy: as you read bits in from your input stream you traverse the tree beginning at the root, taking the left hand path if you read a 0 and the right hand path if you read a 1. When you hit a leaf, you have found the code.
Generally, any Huffman compression scheme also requires the Huffman tree to be written out as part of the file, otherwise the reader cannot decode the data. For a static tree, you don't have to do this since the tree is known and fixed.
حل واجبات الجامعة العربية المفتوحة
اتصل : O544321455 - OO966544321455
واتس اب: 966544321455+
ايميل : [email protected]
سكايبي : a_al_shora
حل واجب (http://www.aswaqcity.com/thread1310656.html) 0.5.4.4.3.2.1.4.5.5 الجامعة العربية المفتوحة
حل واجبات الجامعة العربية المفتوحة O54.4.3.2.1.4.5.5 - OO96654.4.3.2.1.4.5.5
ايميل : a_al_shora @ h.o.t.m.ail.c.o.m
سكايبي: a_al_shora
واتس اب: OO96654.4.3.2.1.4.5.5