Math and Cryptography Flashcard

Front

What is the definition of modular arithmetic?

Back

Modular arithmetic is a system of arithmetic for integers, where numbers wrap around after reaching a certain value, known as the modulus.

Front

How do you compute the modulus of a number?

Back

To compute the modulus of a number, divide the number by the modulus and take the remainder.

Front

What is the result of 72 mod 7?

Back

2

Front

What is a Caesar cipher?

Back

A Caesar cipher is a type of substitution cipher where each letter in the plaintext is 'shifted' a certain number of places down or up the alphabet.

Front

How do you encrypt a word using a Caesar cipher with a shift of 8?

Back

To encrypt a word using a Caesar cipher with a shift of 8, replace each letter with the letter that is 8 positions down the alphabet, wrapping around if necessary.

Front

What is the encrypted form of the word 'STUFF' using a Caesar shift of 8?

Back

ACEQR

Front

What is the modular exponentiation rule?

Back

The modular exponentiation rule states that (a^b) mod m can be simplified using properties of modular arithmetic, often reducing the size of the numbers involved.

Front

What is the result of 138^5 mod 4?

Back

0

Front

How do you compute 66 mod 4?

Back

Divide 66 by 4, which gives a quotient of 16 and a remainder of 2, so 66 mod 4 is 2.

Front

What is the result of 415 mod 31?

Back

12