All Questions
Tagged with playfair classical-cipher
11 questions
1
vote
1
answer
155
views
Can I use a Friedman test when decrypting a Playfair cipher?
I’d like to decrypt a Playfair ciphertext; however, I need to find the key word first. Is it possible to use the Friedman test here to find the length of the key word?
My cipher has no J’s in it would ...
0
votes
1
answer
1k
views
Cracking transposition cipher
I have a task to decrypt custom made transposition cipher, as I'm not the cryptography expert, I would appreciate any help.
I've been given the table of characters ...
...
- 103
2
votes
1
answer
3k
views
How large is the Playfair cipher keyspace? [duplicate]
In the Playfair cipher, is the key space 5 x 5 = 25 or 25 x 25 = 625? I'm trying to work out the size of the key space if each set of equivalent keys is counted as one key.
- 21
-2
votes
1
answer
547
views
Playfair cipher or ADFGX? [closed]
As part of an assignment, I have been given a cipher text of
FFFXXXFGXAGFAFDAFXADDAGAD
with the following description,
...
- 25
1
vote
1
answer
2k
views
How to decode a Playfair message with a partial key?
I've been given a Playfair ciphered message and a partial key, where a few key letters are missing:
Corrupted key (? stands for a missing letter): ...
5
votes
2
answers
32k
views
How to find the keyword of the Playfair cipher, given the plaintext and the ciphertext?
I know how the Playfair cipher works. I would like to know how to find the keyword of the Playfair cipher, given some ciphertext and the corresponding plaintext.
For example:
encrypted: ...
- 145
7
votes
2
answers
8k
views
How does cryptanalysis of the Playfair cipher work?
I have a set of Playfair-enciphered data that I'm trying to crack without the key. I know I need to analyse bigrams; I've currently worked out what decrypts to th, <...
4
votes
1
answer
1k
views
Four-Square cipher and its keyspace
Am I thinking about this correctly?
Consider that the keyspace of the Playfair cipher is equivalent to all permutations of the alphabet, e.g. the number of distinct permutations of 25 objects, and ...
- 41
11
votes
2
answers
18k
views
How many keys does the Playfair Cipher have?
I was just studying the Playfair cipher and from what I've understood, it is just a slightly better version of a Caesar cipher, in that it isn't actually mono-alphabetic but rather the 'digrams' are ...
- 647
7
votes
3
answers
6k
views
How to attack a classical cipher using known partial plaintext?
I have a ciphertext generated by a classical cipher. I do not know what was cipher used to generate it. I do however have the beginning of the plaintext.
What are the cryptanalysis approaches for ...
- 71
22
votes
2
answers
14k
views
What are the main weaknesses of a Playfair cipher, if any?
What are the main weaknesses of a Playfair cipher, if any?
I know that they depend on none of the letters missing, but that is an easy fix if a letter gets dropped. Besides that, are there any other ...
- 403