Season 03 • Episode 08 • What is cryptography ?
0What is cryptography ?
Season 03
Episode 08 Time frame 1 period
Objectives :
•
Introdue the main onepts inryptography.•
Study an exampleof enrypted text.Materials :
•
Voabulary sheet about ryptography.•
The Gold Bug ipher.•
Beamer1 – Brainstorming about cryptography 20 mins
Students work in groups to build a mind map about ryptography and if possible give
examplesofiphers.Voabularyisgivenwhenasked.Eahgroupmustnametworeporters
who will explainthe mindmap tothe lass.
2 – Presentation of some mind maps 20 mins
Some group reporters explain their mindmaps to the lass.
3 – The Gold Bug cipher 15 mins
The Gold Bug ipher is presented and students, working in groups, have 15 minutes to
What is cryptography ?
Season 03
Episode 08
Document Vocabulary sheet
Cryptography : The pratie and study of hidinginformation.
Enryption : The proess of obsuring informationto make itunreadablewithout spe-
ialknowledge,key les, and/orpasswords.
Deryption : The proess reversing an enryption, i.e. the proess whih onverts en-
rypted data into itsoriginalform.
Cipher : A methodof transforming a textin order tooneal itsmeaning.
Code : A ryptographi system that onverts words or phrasesinto odewords.
Codeword : A stringrepresenting an enoded piee of text.
Enode : To onvert areadable text into anunreadable one.
Plaintext : Un-enrypted text, text that isreadable.
Ciphertext : Enoded text, text that is unreadable.
Cryptanalysis : An analysisorderyptingof aspeitextoraspeiode oripher,
The Gold Bug cipher
Season 03
Episode 08 Document Document
The Gold-Bug is a short story by Edgar Allan Poe, set on Sullivan's Island, South
Carolinainvolving deipheringa seret messageand nding buriedtreasure.
Plot summary
The Gold-Bug tells the story of a strange man
named WilliamLegrand who seemingly goes mad
afterndingand beingbitten bya bugthoughtto
bemadeofpuregold.Henotieshislosestfriend,
the narrator, telling himto immediately ome vi-
sit himat his home on Sullivan's Island in South
Carolina.Uponthe narrator's arrival,Legrand in-
forms himthat they are embarkingupon a searh
for lost treasure along with his Afrian-Amerian
servant Jupiter. The narrator has intense doubt
and questions if Legrand has gone insane.
Illustration foran earlyedition
After following several lues, however, hey nd treasure buried by the infamous pirate
Captain Kidd, that is estimated by the narrator to be worth about fourteen million
dollars.Onethetreasure issafelyseured, themangoesintoanelaborateexplanation of
how he knew about the treasure's loation,based on a set of ourrenes that happened
after the disovery of the gold bug.
Cryptography
The story involves ryptography with a detailed desription of a method for solving a
simple substitution ipherusing letter frequenies. The ryptogram is :
53
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305))6∗
;4826)4‡
.)4‡
); 806∗
;4 8†
8$60))85;1
‡
(; :‡∗
8†
83(88)5∗†
;46(;88∗
96∗
?;8)∗‡
(;485);5∗†
2 :∗‡
(;4956∗
2(5∗
4)8$8
∗
;4069285);)6†
8 )4‡‡
; 1(‡
9; 480 81; 8 :8‡
1;48
†
85;4)485†
528 806∗
81(‡
9; 48;( 88; 4(
