# Is the key of this encryption (transposition cipher) correct?

• Comp Sci
• shivajikobardan
In summary, the conversation discusses the correct column numbering for a transposition cipher and the confusion around multiple perspectives. The correct order for the columns is determined based on a given key, but there is some disagreement on this method. One person suggests using the encoding procedure outlined in the textbook, while another believes it is being done incorrectly.
shivajikobardan
Homework Statement
Transposition Cipher
Relevant Equations
no conversion of Plain Text to cipher, just change the position of plaintext.

I don't have much to add in this post as it's apparent from the figure itself.
DAEX
UVFU
RSES is column number 3 not 6. So, I think that's a mistake.

I'm following this book for this sub topic only.

CRYPTOGRAPHY AND NETWORK SECURITY By PRAKASH C. GUPTA

shivajikobardan said:
Homework Statement:: Transposition Cipher
Relevant Equations:: no conversion of Plain Text to cipher, just change the position of plaintext.

RSES is column number 3 not 6. So, I think that's a mistake.
If the ciphertext is the columns written out in increasing key-digit order then it appears correct to me. Not sure what you mean the mistake should be.

Filip Larsen said:
If the ciphertext is the columns written out in increasing key-digit order then it appears correct to me. Not sure what you mean the mistake should be.
uuh it's confusing as there're multiple perspectives.

I first gave columns numbering as it should be, so according to my numbering:
1-GAIO
2-UVFU
3-AETR
4-RSES
5-DAEX
6-LTNX
7-EFHX

And the key here's 5263174
so this'd be the order:
DAEX,UVFU,LTNX,AETR,GAIO,EFHX,RSES

Based on the picture from your textbook alone it seems you are doing it wrong. I understand the encoding procedure to be
1. Write out the clear text one row at a time over 7 columns, padding with X (which seems like a bad idea, but never mind that now).
2. Write the key so one digit is above each column.
3. Write out the ciphertext as the full column marked 1, then 2, and so on up to 7.

## 1. How can I tell if the key of this encryption is correct?

The best way to determine if the key of a transposition cipher is correct is to try decrypting the message with the given key. If the resulting message is readable and makes sense, then the key is likely correct. Another way is to compare the decrypted message with the original message to see if they match.

## 2. What happens if I use the wrong key to decrypt a transposition cipher?

Using the wrong key to decrypt a transposition cipher will result in a message that is either unreadable or makes little sense. This is because the key determines the order in which the letters are rearranged, and using the wrong key will result in a jumbled message.

## 3. Can a transposition cipher be cracked without knowing the key?

Yes, it is possible to crack a transposition cipher without knowing the key, but it can be a difficult and time-consuming process. It often involves trying different key combinations and using frequency analysis to determine the correct key.

## 4. How long should the key be for a transposition cipher to be secure?

The length of the key for a transposition cipher depends on the length of the message. Generally, the key should be at least as long as the message to ensure security. However, using a longer key can make it more difficult for someone to crack the cipher.

## 5. Are there any weaknesses in using a transposition cipher?

One weakness of a transposition cipher is that it does not change the actual letters of the message, only their positions. This means that if someone knows or can guess the key, they can easily decrypt the message. Additionally, frequency analysis can still be used to crack a transposition cipher.

Replies
2
Views
1K
Replies
13
Views
3K
Replies
3
Views
9K
Replies
2
Views
11K
Replies
8
Views
2K
Replies
17
Views
4K
Replies
2
Views
2K
Replies
2
Views
3K