Questions tagged [playfair]
The Playfair cipher is a digraph substitution cipher. It employs a table where one letter of the alphabet is omitted, and the letters are arranged in a 5x5 grid.
28 questions
2
votes
1
answer
86
views
Recommended puzzles? [closed]
I am beginning my journey into Cryptography, having studied a theory-heavy master's degree module, and I have also read The Code Book by Simon Singh, among many other online resources.
What puzzle ...
- 139
0
votes
1
answer
74
views
Key derivation using known parameters of playfair [duplicate]
Is it possible to derive the key, for a playfair cipher, if both the message and cipher text are known?
- 1
0
votes
1
answer
237
views
How would I go about breaking Playfair cipher with the alphabet and the encrypted message? [closed]
I was wondering how I could crack a Playfair cipher with only the alphabet and the ciphered message. Ive tried looking for tools online, but still no luck.
0
votes
1
answer
193
views
Question about the Playfair cipher
The task:
The Playfair cipher with $I = J, X$ added into two same letters and
the key keep distance.
The plaintext:
CORONAVIRUS SPREADS FAST
The whitespaces in plaintext and key are to be ...
- 3
2
votes
2
answers
353
views
How to decode Playfair when only a small part of key is available?
How to decode Playfair when only a small part of key is available?
What is the plain text for this message?
Can someone explain how to recover the plain text for this message?
Is there a program that ...
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 ...
5
votes
1
answer
3k
views
Playfair cipher - questions about inserting 'X'
I'm implementing the Playfair cipher as part of a programming project. I realize there are different versions of the cipher - I've been asked to implement the version which treats the letters 'I' and '...
- 51
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
1
vote
0
answers
518
views
Substitution Cipher Help: Can't figure out keyword [closed]
Given a keyword, you can encrypt a message using alphabetical substitution like this:
...
- 11
-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
2
votes
0
answers
335
views
Decoding the Playfair cipher with a crib [duplicate]
I have a Playfair cipher text and I know a portion of the text (one world). How can I decode the cipher from here? Thanks.
- 121
0
votes
1
answer
513
views
Unicity-distance of Playfair
Given the classical scheme Playfair, say, for 5*5 matrices, I am interested to determine its unicity-distance. How should one proceed to properly do that? I should appreciate it, if I could obtain a ...
- 1,312
1
vote
1
answer
353
views
Playfair Cipher Confusion with one column encryption
Recently I decided to learn "Playfair Cipher", and I have hit a road block.
what do i substitute the letters for if they are on the same column? Here is an example:
...
- 13
1
vote
1
answer
444
views
How to create and validate potential grids when attacking a Playfair cipher?
First up: I am not asking you to decypher anything. This question is about attacking a Playfair cipher; more specifically – how to create potential grids when doing so.
I'm currently working on a ...
- 13
2
votes
0
answers
51
views
Does the length of the keyword used for keytable for Playfair matter?
So for Playfair, we choose a keyword and put that in the keytable with no duplicates. Then, we fill the rest of the table with alphabets in order that are not in the keyword without 'J'.
Does the ...
- 133
3
votes
1
answer
3k
views
Playfair Cipher + Vigenère Cipher?
I'm researching cryptography for a school project, came across the above two ciphers, and something occurred to me. Would combining these two schemes give a considerably stronger encryption than ...
- 31
-4
votes
1
answer
366
views
encryption of message "DATACONFANTIALITY" with key playfair using playfair cipher
actually i have solved the above mentioned problem but i want to check weather it is correct or not. my question is that how to encrypt the message DATACONFANTIALITY using the playfair cipher where ...
- 11
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, <...
1
vote
1
answer
714
views
Multi-round Transposition/Playfair as a secure hand cipher in the computer age [closed]
Given that computers can be easily compromised, there is a need for a hand cipher that can withstand computer attack. Clearly the traditional hand ciphers fail.
One time pads work. They also have ...
- 188
1
vote
1
answer
2k
views
Encryption of numeric value using playfair
I am studying in CSE and in my recent exam paper, A question was asked as:
Construct a playfair cipher for Plaintext: semester5 and key:technology.
Generally as we are taught yet, there is no ...
- 13
-1
votes
1
answer
3k
views
Number of possible keys in a Play fair cipher [duplicate]
So for the play fair case, the number of possible keys is : 26x26 = 676 possible keys
But if we consider the repeated letters, how many unique keys will the play fair have? I mean how will ...
- 445
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