[CCCure CISSP] Qs5 Cryptography: cccure QuizEngn doubts

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[CCCure CISSP] Qs5 Cryptography: cccure QuizEngn doubts

Amlan Deb
Hello everyone,
 
I have some doubts regarding some cccure Quiz questions and concepts mentioned below. Would really appreciate it if you could take out some time and help me with them. Request you to please provide a quick reply as I need to appear for the exam in the month of July.
 
Thanks,
Amlan
 

Doubt#5
========

125. 

1.     Question: 1398 | Difficulty: 5/5 | Relevancy: 3/3

Which of the following would best describe a Concealment cipher?

o      Permutation is used, meaning that letters are scrambled.

o     Every X number of words within a text, is a part of the real message.

o      Replaces bits, characters, or blocks of characters with different bits, characters or blocks.

o      Hiding data in another message so that the very existence of the data is concealed.

You did not provide any answer to this question. Please review details below.

When a concealment cipher is used, every X number of words within a text, is a part of the real message. The message is within another message.

Concealment ciphers include the plaintext within the ciphertext. It is up to the recipient to know which letters or symbols to exclude from the ciphertext in order to yield the plaintext. Here is an example of a concealment cipher:

i2l32i5321k34e1245ch456oc12ol234at567e

Remove all the numbers, and you'll have i like chocolate. How about this one?

Larry even appears very excited. No one worries.

The first letter from each word reveals the message leave now. Both are easy, indeed, but many people have crafted more ingenious ways of concealing the messages. By the way, this type of cipher doesn't even need ciphertext, such as that in the above examples.

Consider the invisible drying ink that kids use to send secret messages. In a more extreme example, a man named Histiaeus, during 5th century B.C., shaved the head of a trusted slave, then tattooed the message onto his bald head. When the slave's hair grew back, Histiaeus sent the slave to the message's intended recipient, Aristagoros, who shaved the slave's head and read the message instructing him to revolt.

 

A transposition cipher uses permutations.

A substitution cipher replaces bits, characters, or blocks of characters with different bits, characters or blocks.

Steganography refers to hiding the very existence of the message.

 

Source: WALLHOFF, John, CBK#5 Cryptography (CISSP Study Guide), April 2002 (page 1). Available at http://www.cccure.org.

and also see:

http://www.go4expert.com/forums/showthread.php?t=415 

Last modified 07/02/2007, Ron Hehemann
Thanks to Vince Martinez for reporting an issue within the text of the explanations.

Contributor: Christian Vezina

 

My doubt: Option ‘D’ seems to better describe how concealment cipher works here – and even includes option ‘B’ (whereas option ‘B’ doesn’t include option ‘D’). Why can’t option ‘D’ be the answer?

Even if we say that option ‘D’ refers to the definition of Steganography - Steganography is also a type of Concealment cipher. Why can’t option ‘D’ be the answer?

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Re: [CCCure CISSP] Qs5 Cryptography: cccure QuizEngn doubts

clementdupuis
Administrator
Good day Amlan,

Choice A does not describe Steganography.    Steganography is covert, the existence of the message itself is not even known.  With concealment cipher the message within the message is visible if you know how to read it.

Steganography is hidden writing.

Concealment is mostly hiding a message within another message.

Steganography is hiding data within another medium.

Best regards

Clement



My doubt: Option ‘D’ seems to better describe how concealment cipher works here – and even includes option ‘B’ (whereas option ‘B’ doesn’t include option ‘D’). Why can’t option ‘D’ be the answer?

Even if we say that option ‘D’ refers to the definition of Steganography - Steganography is also a type of Concealment cipher. Why can’t option ‘D’ be the answer?

Choice A does not describe Steganography.


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On Sun, Jun 2, 2013 at 4:22 PM, Amlan Deb <[hidden email]> wrote:
Hello everyone,
 
I have some doubts regarding some cccure Quiz questions and concepts mentioned below. Would really appreciate it if you could take out some time and help me with them. Request you to please provide a quick reply as I need to appear for the exam in the month of July.
 
Thanks,
Amlan
 

Doubt#5
========

125. 

1.     Question: 1398 | Difficulty: 5/5 | Relevancy: 3/3

Which of the following would best describe a Concealment cipher?

o      Permutation is used, meaning that letters are scrambled.

o     Every X number of words within a text, is a part of the real message.

o      Replaces bits, characters, or blocks of characters with different bits, characters or blocks.

o      Hiding data in another message so that the very existence of the data is concealed.

You did not provide any answer to this question. Please review details below.

Details

Submit a comment on this question

When a concealment cipher is used, every X number of words within a text, is a part of the real message. The message is within another message.

Concealment ciphers include the plaintext within the ciphertext. It is up to the recipient to know which letters or symbols to exclude from the ciphertext in order to yield the plaintext. Here is an example of a concealment cipher:

i2l32i5321k34e1245ch456oc12ol234at567e

Remove all the numbers, and you'll have i like chocolate. How about this one?

Larry even appears very excited. No one worries.

The first letter from each word reveals the message leave now. Both are easy, indeed, but many people have crafted more ingenious ways of concealing the messages. By the way, this type of cipher doesn't even need ciphertext, such as that in the above examples.

Consider the invisible drying ink that kids use to send secret messages. In a more extreme example, a man named Histiaeus, during 5th century B.C., shaved the head of a trusted slave, then tattooed the message onto his bald head. When the slave's hair grew back, Histiaeus sent the slave to the message's intended recipient, Aristagoros, who shaved the slave's head and read the message instructing him to revolt.

 

A transposition cipher uses permutations.

A substitution cipher replaces bits, characters, or blocks of characters with different bits, characters or blocks.

Steganography refers to hiding the very existence of the message.

 

Source: WALLHOFF, John, CBK#5 Cryptography (CISSP Study Guide), April 2002 (page 1). Available at http://www.cccure.org.

and also see:

http://www.go4expert.com/forums/showthread.php?t=415 

Last modified 07/02/2007, Ron Hehemann
Thanks to Vince Martinez for reporting an issue within the text of the explanations.

Contributor: Christian Vezina

 

My doubt: Option ‘D’ seems to better describe how concealment cipher works here – and even includes option ‘B’ (whereas option ‘B’ doesn’t include option ‘D’). Why can’t option ‘D’ be the answer?

Even if we say that option ‘D’ refers to the definition of Steganography - Steganography is also a type of Concealment cipher. Why can’t option ‘D’ be the answer?


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_______________________________________________
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CISSPstudy mailing list
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To UNSUBSCRIBE, SUBSCRIBE, or MANAGE your accout visit the link below:
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