2007年5月27日 星期日

outside reading

Learn Secret Codes

Can you keep a secret? How would you send a secret message? What if it fell into the wrong hands? Spies and the military of all nations have been sending secret messages since ancient times. They all developed ingenious codes to protect their battle plans and valuable information from prying eyes. The art of encoding or decoding these secret messages is called “cryptography.”

Howt owri tesec retmes sag esi nco de Can you guess what the title of this section says? If you look closely, you will see that it is “How to write secret messages in code,” with the spaces between words changed. That’s just one way to create a secret code. Another way is a system of cryptography called “ciphers”.
In the system of ciphers, letters of the alphabet are rearranged in different ways or letters are substituted for other letters. Here are just 3 examples of how ciphers are used to hide the sentence, “I HAVE A SECRET TO KEEP.”
Writing the sentence backwards: PEEK OT TERCES A EVAH I
Writing the sentence using the alphabet backwards from Z to A instead of A to Z so that A=”Z,” B=”Y,” C=”X,” D=”W” and so on: R SZEV Z HVXIVG GL PVVK
Writing the sentence using an alphabet with the letters rearranged, for example, G R Z M A O B Q C T U J K D E X P H Y I V L N Q W F (so that G=”A,” R=”B,” Z=C, M=”D,” and so on): C QGLA G YAZHAI IE UAAX
Numbers Another way to encode a message is to use numbers in place of some or all of the letters of the alphabet. If you know that 1=”S,” 2=”T,” 3=”R,” 4=”O,” 5=”G,” 6=”D,” 7=”P,” 8=”E,” 9=”A,” you can read the following message:
C4n5392ul92i4n1 4n 68c46in5 2hi1 18c382 m811958!


Reaction

After I read this essay ,I feel that secret codes are not difficult to learn no matter chilren amd adults. It is very interesting if you know the rule of codes. I think secret codes can be uesed in the game between parents and their children because they can use secret codes to write something to talk with each other.It can improve the love between parents and children.

secret codes for spies?

Summary

This lesson told us that although we are common people, we use secret codes in our daily life .When we locked the bicycle, we used numerical look on it. When we went to supermarket to buy something that merchandises are given bar codes for people to identity them. Also, we can know that the origin of Enigma code. First, it was developed to communicate with brunches of companies. And then German military found that Enigma code was a great apparatus to create unbreakable codes.
Although many people wanted to crack Enigma code, they couldn’t crack the impediments of Enigma lode until Alan Turing cracked it .Those people who in the Alan Turing were unrecognized after they had died.

Reaction

After I read the lesson, “secret codes for spies?” I knew that although common people were not spies, they all used secret codes every day such us bar codes and PIN .Also, I knew the origin of Enigma code, and how it developed in German military. It was a special and great invention for military.