Caesar Cipher

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Alexander Corner

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2 years, 7 months ago

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Question statement

This question will allow you to check your understanding of the Caesar Cipher by encrypting a short message given a random key. You may find this website of ten letter words useful for this question.

Give any introductory information the student needs.

			Name	Type	Generated Value

caesar_key	integer	20
plaintext	string	pacesetter
plaintext0	string	p
plaintext1	string	a
plaintext2	string	c
plaintext3	string	e
plaintext4	string	s
plaintext5	string	e
plaintext6	string	t
plaintext7	string	t
plaintext8	string	e
plaintext9	string	r
ascii_lower	dict	Dictionary with 26 entries
ascii_upper	dict	Dictionary with 26 entries
ascii_upper_cipher	dict	Dictionary with 26 entries
ciphertext0	string	J
ciphertext1	string	U
ciphertext2	string	W
ciphertext3	string	Y
ciphertext4	string	M
ciphertext5	string	Y
ciphertext6	string	N
ciphertext7	string	N
ciphertext8	string	Y
ciphertext9	string	L
ciphertext	string	JUWYMYNNYL

Automatically regenerate variables?

Name

Data type

Value

xxxxxxxxxx
 
random(1..25)

JME function reference

Description

Describe what this variable represents, and list any assumptions made about its value.

Can an exam override the value of this variable?

Generated value: `integer`

→ Used by:

ascii_upper_cipher

This variable doesn't seem to be used anywhere.

Parts

Explore mode options

Word Entry Gap-fill
1. Gap Plaintext Match text pattern
  Add
Encryption Gap-fill
1. Gap Ciphertext Match text pattern
  Add

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Maximum mark

(sum of objective limits)

Objectives

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Advice

Recall that plaintext should be entered as lower case and ciphertext should be entered as upper case.

Suppose that your word was "{plaintext}". Each character of the word "{plaintext}" is encrypted separately, using the key $k = \var{caesar_key}$ : $c_i = m_i + k~(\operatorname{mod} 26)$ . We are mapping letters to numbers by their place in the alphabet, so "a" corresponds to $0$ , "b" corresponds to $1$ , ..., "z" corresponds to $25$ .

For example, the first letter of this word (in position $0$ ) is "{plaintext0}", which corresponds to $\var{ascii_lower[plaintext0]-97}$ . So $c_0 = m_0 + k~(\operatorname{mod} 26) = \var{ascii_lower[plaintext0]-97} + \var{caesar_key}~(\operatorname{mod} 26) = \var{mod(ascii_lower[plaintext0]-97 + caesar_key,26)}~(\operatorname{mod} 26)$ . This corresponds to " $\var{upper(keys(ascii_lower)[mod(ascii_lower[plaintext0]-97 + caesar_key,26)])}$ ".

We carry on to do this for each letter, which for the word "{plaintext}" would eventually give the ciphertext "{ciphertext}".

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Match text pattern
Match text pattern		Hasn't run yet
Gap-fill
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This question is used in the following exam:

Maths and Cryptography Exam Practice by Alexander Corner in Intro Cryptography.

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Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

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Checkpoint description

Alexander Corner 2 years, 7 months ago

Alexander Corner 2 years, 7 months ago

Alexander Corner 2 years, 7 months ago

Error in variable testing condition

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Generated value: `integer`

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Caesar Cipher

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

Alexander Corner 2 years, 7 months ago

Alexander Corner 2 years, 7 months ago

Alexander Corner 2 years, 7 months ago

Error in variable testing condition

Error

Warning

Generated value: integer

Parts

Objectives

Penalties

Generated value: `integer`