1. There are 25 blocks in the playfair cipher. So there are
25! possible
keys.
How many possible keys are there for a playfair cipher justify your answer?
1. There are 25 blocks in the playfair cipher. So there are
25! possible keys
.
How many keys are possible in cipher?
Since there are only
25 possible keys
(each possible shift of the alphabet), we just try decrypting the ciphertext
What is key in playfair cipher?
The key square is
a 5×5 grid of alphabets that acts as the key for encrypting the plaintext
. Each of the 25 alphabets must be unique and one letter of the alphabet (usually J) is omitted from the table (as the table can hold only 25 alphabets).
What are the rules of playfair cipher?
- When the two letters are in different rows and columns, each is replaced by the letter that is in the same row but in the other column; i.e., to encrypt WE, W is replaced by U and E by G.
- When A and R are in the same row, A is encrypted as R and R (reading the row cyclically) as M.
How many possible keys exist for a cipher that uses a key containing 5 bits?
The problem with a 5 bit key is that it only has
32 combinations
.
How many keys are available with a three bit key?
In fact every time we increase the length of the key by one bit we double the number of possible keys – so a three-bit key has
eight possible values
– 000, 001, 010, 011, 100, 101, 110 and 111.
What is Playfair key Matrix?
The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is
a manual symmetric encryption technique
and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair for promoting its use.
Is playfair cipher a block cipher?
Playfair ciphers are
a type of block cipher
: the ciphertext
Is Playfair Polyalphabetic cipher?
Polyalphabetic Cipher is a
substitution
cipher in which the cipher alphabet for the plain alphabet may be different at different places during the encryption process. The next two examples, playfair and Vigenere Cipher are polyalphabetic ciphers.
Which of the following Cannot be chosen as a key in Playfair cipher?
2) Which of the following cannot be chosen as a key in the Caesar cipher? Explanation: In Caesar cipher, we can choose a number or a character which when performed addition modulo operation with the given letters of the plain text gives us ciphertext. However,
a string
cannot be chosen for encryption in this case.
Is Playfair cipher better than Hill cipher?
Hill cipher is harder to crack than playfair cipher
. Explanation: Both hill cipher and playfair cipher are less vulnerable to frequency analysis. But hill cipher is quite vulnerable to other forms of attack and thus less secure than playfair cipher.
How many keys does the Triple DES algorithm use?
Triple DES specifies the use of
three distinct
DES keys, for a total key length of 168 bits.
How many possible keys are there when using a cipher with a key size of 128 bits?
A 128-bit level of encryption has
2128 possible key
combinations (340,282,366,920,938,463,463,374,607,431,768,211,456 – 39 digits long) and 256-bit AES encryption has 2256 possible key combinations (a number 78 digits long).
How many possible keys are there for a 192 bit key?
In AES-192 key expansion there are 12 rounds and
52 keys
. I am not sure why 52 keys are derived since each block consist of 4 rows and 6 columns (192 bit keys). So if the block is 4 x 4 then we simply multiply rounds with key size. 13 x 4 = 52 but here we have 4 x 6 matrix (block).
How many keys are used by public key?
In a public key system,
two keys
are used, one for encrypting and one for decrypting. The two keys are mathematically related to each other but knowing one key does not divulge the other key. The two keys are called the “public key” and the “private key” of the user.
