While working full time, havn't really been paying attention.
class is crime and computer then they threw out this curve ball.

Anyone know how you do this stuff?



1. [5 marks] Let’s get some practice with the binary and hexadecimal number systems
a. Convert the hex value B1C0D4 into binary
b. Convert the binary value 0111 1100 1001 0001 0101 1101 1011 0011 into hex.
c. What is DA3FFD + 3 equal to (assuming hex values)?
d. What is FF + 11 equal to (assuming hex values)?
e. What is B56D3 + 2C56A equal to (assuming hex values)?

2. [4 marks] Now let’s get some practice converting text to its hex equivalent value.
a. Give the ASCII representation in hex for the word Trent
b. Give the ASCII representation in hex for the phrase COIS2750h
c. Give the ASCII representation in hex for the phrase Have Fun!
d. Give the text message represented by the following hex digits
50 69 65 63 65 20 6F 66 20 63 61 6B 45

For part 1 google "hex to binary converter"
for part 2 google "text to ASCII converter"
now you know how to use google, which is the real objective of this homework

This post was edited by Exx on Jul 9 2015 11:36pm

a)
1011 0001 1100 0000 1101 0100
b )
7C915D3
d)
FF = 1111 + 1111 = 011110
11 = 1011
011110 + 1011 = 0101011

I think you can figure out C and E now given

0000 = 0
0001 = 1
0010 = 2
0011 = 3
0100 = 4
0101 = 5
0110 = 6
0111 = 7
1000 = 8
1001 = 9
1010 = A
1011 = B
1100 = C
1101 = D
1110 = E
1111 = F

If you have more questions let me know
I've taken a whole course on digital logic
dn8 0.3 m8?

This post was edited by marioo1182 on Jul 10 2015 12:13am

I do have another,

I have completed all the other Q's i posted and the other sections but this one is over my head



4.[9 marks] Now let’s look at a more modern symmetric encryption. Assume that the algorithm for this system is to rotate the bits in the message right 8positions, XOR the bits with the key, and rotate the bits 3 positions to the left.
a. I will email you the key which is encoded within a spam email message. Please be on the
lookout for this message. Once you receive the email go to http://www.spammimic.com/
and click on Decode. Cut and paste the body of your email into the Decode window and
get the key. The key will be 2hex numerals. If you don't get 2 hex numerals when you
decode the message, you haven't copied the entire email message. What is the key?

Went to the site decoded the E-mail got:
59

b. Using the key and the above algorithm, decrypt the following name (given in hex): 50 A0 C0 58.
Remember that you’ll have to reverse the order and direction of operations in order to decrypt the name (i.e.Start by rotating 3positions right). What is the name?

c.The answer to part b is the name of a Roman god. Find (and state) the name of his
Mother and, using the key and the above algorithm, encrypt the name(in upper case)
and put in hex format.



No idea what is meant by XOR the bits

XOR is an "exclusive or" operation, which means that the result of the operation is 1 when the bits are different, and 0 when they are the same. That is, 1 XOR 1 = 0, but 1 XOR 0 = 1.
So what you need to do is convert the hex name to binary, then do the operations he talks about

50 A0 C0 58 to binary is
0101 0000 1010 0000 1100 0000 0101 1000

Rotate 3 bits to the right
0000 1010 0001 0100 0001 1000 0000 1011

59 in binary is 0101 1001. So we XOR the bits above with these and get



Rotate 8 left
0001 0100 0001 1000 0101 0010 0000 1010

Convert to hex:
1418520A

Doesn't look like any Roman god name to me though. Pretty sure your teacher fucked up a little, because I don't think there are any Roman god names that can be formed from ABCDEF. Unless he's doing leet speak or something.

This post was edited by russian on Jul 10 2015 09:59am

Thanks man! I'll keep trying to play with it!

Alternate interpretation of rotating is not better

Right 3 spots:
1000 0101 0000 0110 0000 0010 1100 0010

0101 1001

1000 0101 0000 0110 0000 0010 1001 1111

8 position left:
1001 1111 1000 0101 0000 0110 0000 0010

Text:Ÿ…


Maybe i need to account for 0000 for spaces? le sigh

This post was edited by Nearin on Jul 10 2015 10:11am

Considering he had ACII to hex in the first part, I'm guessing that maybe the answer is supposed to be 4 letters, represented by pairs of hex ASCII codes. However, the correct answer is still
14 18 52 0A
which doesn't convert to anything meaningful in ASCII

Well i'll puzzle over it a little more, but i have everything else correct so i may just submit this for part marks.

Thanks for the help everyone!

Oh I see what the problem is. Your teacher didn't say the key should be repeated. If you repeat the key you get



Rotate 8 left
0101 0010 0101 0011 0100 1101 0100 0001

Convert to hex:
52 53 4D 41

Look up ASCII table and you get
M A R S