## Related questions with answers

The ciphers in the earlier problems are called substitution ciphers because of the substitution technique used. A cipher is an algorithm used for encryption and decryption. Generally, there are two related algorithms, one for encryption and one for decryption. A substitution cipher is an algorithm that encrypts a message by replacing each character in the plaintext with another character. The receiver reverses the substitution to decrypt the message. A key typically consists of the information needed to carry out the encryption (or decryption) process. In a shift substitution cipher, a key is typically a number. For example, the key in a Caesar cipher is the number of places down the alphabet that you must shift.

a. What is the key for the Caesar cipher in the earlier problem?

b. What is the key for the ROT13 cipher?

c. Substitution ciphers like ROT13 and Caesar ciphers are not very secure. That is, it is not very difficult to decrypt the ciphertext even if you do not know the key. Describe some general strategies you think could be used to break substitution ciphers like those above.

d. Create your own substitution cipher. Encrypt a brief message. Then exchange encrypted messages with a classmate and try to decrypt each other's messages. Discuss and resolve any difficulties in the decryption process.

Solution

Verifieda.)

Since the message had to be shifted $23$ letter down the alphabet, the key is $23$.

## Create a free account to view solutions

## Create a free account to view solutions

## Recommended textbook solutions

#### Transition to College Mathematics and Statistics

1st Edition•ISBN: 9780076626267Ann E. Watkins, Beth E. Ritsema, Christian R. Hirsch, Eric W. Hart#### Cambridge IGCSE Mathematics Core and Extended

4th Edition•ISBN: 9781510421684Ric Pimentel#### Big Ideas Math Integrated Mathematics II

1st Edition•ISBN: 9781680330687Boswell, Larson#### Big Ideas Math Integrated Mathematics III

1st Edition•ISBN: 9781680330878Boswell, Larson## More related questions

1/4

1/7