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Exclusive OR Part a requires you to encrypt the plaintext Part b requires you to

ID: 3593073 • Letter: E

Question

Exclusive OR

Part a requires you to encrypt the plaintext

Part b requires you to covert the encrypted text to plaintext

a) Plaintext “SECURITY”

Create the binary of each ASCII letter

Apply the Cypher Key “6” (00110110) to encrypt using “Exclusive OR” the plain text

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Plaintext

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Plainbinary:

Cypher Key

Cipher Answer:

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Plaintext

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Plainbinary:

Cypher Key

Cipher Answer:

b) Encrypted: “7(342”

Find the plaintext

Unencrypt this was encrypted applied with “a” (01100001):

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Answer Plaintext

Plain binary:

Cypher Key

Cipher binary:

Cipher text:

7

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Plaintext

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Plainbinary:

Cypher Key

Cipher Answer:

Explanation / Answer

a)

We have to first find out the binary representation corresponding to the ASCII value for each of the characters n the given plain text. For example, the ASCII value corresponding to 'S' is 83. The binary representation for the same is

01010011. SImilarly, we have to find for others as well and copy the cipher equvalent to 6 (00110110) in the cipher key columns. Then we have to perform Exclusive OR over the plain text and cipher text. This operation gives a true output (1) only when the inputs differ ie one is true and the other is false.

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Plaintext

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Plainbinary:

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Cipher Answer:

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Plaintext

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Plainbinary:

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Cipher Answer:

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Hence the encrypted form is obtained by converting the binary form to the corresponding characters .

Upon conversion, the encrypted text becomes " esucdDELbo"

b) Here we have to convert encrypted text into plain text. So we have to convert the each of the characters in cipher text to binary and then apply exclusive operation of the converted binary form over the cipher key.

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Answer Plaintext

V

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S

Plain binary:

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Cypher Key

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Cipher binary:

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Cipher text:

7

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The plain text is obtained by converting the "answer plain text" form into corresponding decimal form (ASCII) and then converting the same into characters.

Upon converting the plain text to decimal, it becomes 86 73 82 85 83. While converting these ASCII values into corresponding characters , we get the output as "VIRUS"

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Plaintext

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Plainbinary:

0 1 0 1

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Cipher Answer:

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