Use a two-stage transposition technique to encrypt the following message using t
ID: 3913419 • Letter: U
Question
Use a two-stage transposition technique to encrypt the following message using the key "Decrypt". Ignore the comma and the period in the message. Message: "The Transposition cipher technique works by permuting the letters of the plaintext. It is not very secure, but it is great for learning about cryptography." In a 3–4 page summary, discuss the following: Is it possible to decrypt the message with a different key? Justify your answer. Do you agree with the statement of the message? Why or why not? Give at least two examples that support your view.
Explanation / Answer
Message: "The Transposition cipher technique works by permuting the letters of the plaintext. It is not very secure, but it is great for learning about cryptography."
Key: Decrypt.
The key is of length 7. So construct a matrix made from the message having 7 columns.
1 2 3 4 5 6 7
T H E T R A N
S P O S I T I
O N C I P H E
R T E C H N I
Q U E W O R K
S B Y P E R M
U T I N G T H
E L E T T E R
S O F T H E P
L A I N T E X
T I T I S N O
T V E R Y S E
C U R E B U T
I T I S G R E
A T F O R L E
A R N I N G A
B O U T C R Y
P T O G R A P
H Y X Y Z A B
In order to create the cipher text, we first alphabetically arrange the key - CDEPRTY (3126475). Going down the matrix following CDEPRTY (column number) gives the cipher text.
Cipher Text: CIUQTHTTTEGCIGMTRTR EEFOLBUVYTRSTIIOPEB OFNRTPBUAELINTKEBGG YRTEANAORSANSIPAHSR ETOSCHLTHERWRYHEIHN IISSATITRUTTOEXYOYZ EEXUIPORNNAPENREPTC
Transposition cipher is not very secure as the letters of the message do not change, transposition cipher technique works by permuting the letters of the plaintext and is may not be very secure. We have use such a key that increases the permutation of the message. Having a simple key of size 3 or less can easily be decoded using trail and error method. So we cannot use any word to decrypt using transposition technique.
Cipher text: EOCEEYIEFITERIFNUOX TSORQSUESLTTCIAABPH HPNTUBTLOAIVUTTROTY ATHNRRTEEENSURLGRAA TSICWPNTTNIRESOITGY NIEIKMHRPXOETEEAYPB RIPHOEGTHTSYBGRNCRZ
For a 2nd stage, the same procedure is followed again cipher text acts as the plain text. key- Decrypt
1 2 3 4 5 6 7
E O C E E Y I
E F I T E R I
F N U O X T S
O R Q S U E S
L T T C I A A
B P H H P N T
U B T L O A I
V U T T R O T
Y A T H N R R
T E E E N S U
R L G R A A T
S I C W P N T
T N I R E S O
I T G Y N I E
I K M H R P X
O E T E E A Y
P B R I P H O
E G T H T S Y
B G R N C R Z
For the 2nd stage, go down the matrix following CDEPRTY (3126475) to get the actual cipher text.
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