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...cryptology? Cryptography? Plaintext? Ciphertext?...

<< Back to: Cryptography FAQ (01/10: Overview)

Question by gupta
Submitted on 2/10/2004
Related FAQ: Cryptography FAQ (01/10: Overview)
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What is cryptology? Cryptography? Plaintext? Ciphertext? Encryption? Key?


Answer by Mohan
Submitted on 2/15/2004
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Cryptography: is the science of keeping the messages secret and ensuring authentication.

Cryptology: is the combined study of Cryptography and Cryptoanalysis*. (Origin: Greek, kryptos="hidden", logos="science").
*Cryptoanalysis is the art of deciphering the ciphertext message.

-Mohan
(sandglass@rediffmail.com)

 

Answer by Linda
Submitted on 3/27/2004
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Cryptography is the art and science of keeping messages secure.
It is derived from the two Greek words -'kryptos' which means 'secret' and 'graph' which means 'writing'.
Cryptanalysis is the art of breaking the cipher text( or the encrypted plain text* ).
Cryptology is the study of both cryptography and cryptanalysis.
{*Plain text is an intelligible message.)

 

Answer by abhinetri_cse_bvrit
Submitted on 1/22/2005
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according to me.,
      cryptography is the art of science.
  it is the science of art.
   actually....,
        i too don't know about it.
         If u know please tell to me.

 

Answer by beans
Submitted on 4/13/2006
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Most people seem to think that the thing to do is weigh six coins against six coins, but if you think about it, this would yield you no information concerning the whereabouts of the only different coin. As we already know that one side will be heavier than the other. So that the following plan can be followed, let us number the coins from 1 to 12. For the first weighing let us put on the left pan coins 1,2,3,4 and on the right pan coins 5,6,7,8. There are two possibilities. Either they balance, or they don't. If they balance, then the different coin is in the group 9,10,11,12. So for our second weighing we would put 1,2 in the left pan and 9,10 on the right. If these balance then the different coin is either 11 or 12. Weigh coin 1 against 11. If they balance, the different coin is number 12. If they do not balance, then 11 is the different coin. If 1,2 vs 9,10 do not balance, then the different coin is either 9 or 10. Again, weigh 1 against 9. If they balance, the different coin is number 10, otherwise it is number 9. That was the easy part. What if the first weighing 1,2,3,4 vs 5,6,7,8 does not balance? Then any one of these coins could be the different coin. Now, in order to proceed, we must keep track of which side is heavy for each of the following weighings. Suppose that 5,6,7,8 is the heavy side. We now weigh 1,5,6 against 2,7,8. If they balance, then the different coin is either 3 or 4. Weigh 4 against 9, a known good coin. If they balance then the different coin is 3, otherwise it is 4. Now, if 1,5,6 vs 2,7,8 does not balance, and 2,7,8 is the heavy side, then either 7 or 8 is a different, heavy coin, or 1 is a different, light coin. For the third weighing, weigh 7 against 8. Whichever side is heavy is the different coin. If they balance, then 1 is the different coin. Should the weighing of 1,5, 6 vs 2,7,8 show 1,5,6 to be the heavy side, then either 5 or 6 is a different heavy coin or 2 is a light different coin. Weigh 5 against 6. The heavier one is the different coin. If they balance, then 2 is a different light coin.

 

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