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2. how many keys are possible in the affine crypto system

by Bret Quigley Published 1 year ago Updated 6 months ago

The affine cipher has 2 key numbers, 'a' and 'b'. 'b' can range from 0 to 25, and 'a' can have any of the values 1,3,5,7,9,11,15,17,19,21,23,25. We iterate over each of these possible combinations, of which there are 311, determine the fitness of each combination, then chose the best.

How many different choices of affine cipher parameters are possible?

If b = 0, then we refer to this cipher as a decimation cipher. (Note that since there are 12 valid choices of a and 26 valid choices of b, there are 12×26 = 312 possible valid affine ciphers.) Also note that if a = 1, then E(x)=(x + b) MOD 26 is simply a Caesar (+b) shift cipher.

What is the key domain of affine cipher?

Affine Ciphers Figure 1 Affine cipher Page 3 The affine cipher uses a pair of keys in which the first key is from Z26 * and the second is from Z26 . The size of the key domain is 25 × 11 = 275.

What is the number of possible 3x3 affine cipher transformation?

4. What is the number of possible 3 x 3 affine cipher transformations ? Explanation: Since 'A' cannot have columns of '0's. so there are '7' choices i.e. 001/010/011/100/101/110/111.

How many keys are possible if we work Mod 28?

– so we have 28 · 29 = 812 keys. Caesar wants to arrange a secret meeting with Marc Antony, either at the Tiber (the river) or at the Coliseum (the arena). He sends the ciphertext 'EVIRE'. However, Marc Antony does not know the key, so he tries all possibilities.

How many keys are in affine cipher?

The affine cipher has 2 key numbers, 'a' and 'b'. 'b' can range from 0 to 25, and 'a' can have any of the values 1,3,5,7,9,11,15,17,19,21,23,25. We iterate over each of these possible combinations, of which there are 311, determine the fitness of each combination, then chose the best.

How many one to one affine Caesar ciphers are there?

The 312 affine ciphers include, as special cases, the 26 Caesar ciphers (the affine ciphers with m = 1; C = p + b) and the multiplicative ciphers (the affine ciphers with b = 0, C = mp).

How many combinations of keys can be constructed from a 72 ciphertext stream cipher?

How many combinations of keys can be constructed from a 72 ciphertext stream cipher? Explanation: For stream cipher, if there are n ciphertexts then there are n*(n−1)/2 combination of keys to be made. = 2556.

How many keys does the Triple DES algorithm use Mcq?

How many keys does the Triple DES algorithm use? Explanation: For Triple DES we can either have 2 or 3 keys. Using three keys: c = Ek3(Ek2(Ek1(m))).

What is the size of the key in the DES algorithm?

10 bits
Explanation: The size of the key in the SDES algorithm is 10 bits.

How many possible keys are there for an affine cipher modulo 26?

We can also calculate all the possible keys for the Affine Cipher. Since, for the standard alphabet, there are 12 numbers less than 26 which are coprime to 26, and for each of these there are 26 possibilities for the value of b, we have a total of 12 x 26 = 312 possible keys for the Affine Cipher.

What does MOD 26 mean?

Mod 26 means you take the remainder after dividing by 26. So 36 mod 26 would give you 10. As a result, shifting by 26 is the same as not shifting by zero.

What is the value of MOD 26?

For example, the elements of the integers modulo (often shortened to “mod”) 26 are 0,1,...,24,25. Then 31 is equivalent to 5 modulo 26, written 31 ≡ 5 mod 26, because when 31 is divided by 26 the remainder is 5.

What is an affine cipher?

The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. The formula used means that each letter encrypts to one other letter, and back again, ...

What is the Caesar cipher?

The Caesar cipher is an Affine cipher with a = 1 since the encrypting function simply reduces to a linear shift. The Atbash cipher uses a = −1 . Considering the specific case of encrypting messages in English (i.e. m = 26 ), there are a total of 286 non-trivial affine ciphers, not counting the 26 trivial Caesar ciphers.

Is Caesar a monoalphabetic cipher?

Since the affine cipher is still a monoalphabetic substitution cipher, it inherits the weaknesses of that class of ciphers. The Caesar cipher is an Affine cipher with a = 1 since the encrypting function simply reduces to a linear shift. The Atbash cipher uses a = −1 .

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