GCD
Divisor Algorithm and Modular Arithmetic
Encryption
Decryption
100

Find the greatest common divisor d of 897 and 559.

13

100

Calculate

32746\equiv x \mod 23

x=17

100

Encrypt the following message with a shift of +7 

Logic is the foundation of the certainty of all the knowledge we acquire

Svnpj pz aol mvbukhapvu vm aol jlyahpuaf vm hss aol ruvdslknl dl hjxbpyl

100

Decrypt this message encrypted using the Caesar Cipher. 


Vs V unir frra shegure guna bguref, vg vf ol fgnaqvat hcba gur fubhyqref bs tvnagf

If I have seen further than others, it is by standing upon the shoulders of giants (+13)

200

Find the greatest common divisor d of 201 and 84.

3

200

Calculate

87963245\equiv x \mod 174

x=155

200

Encrypt the following message with a keyword cipher. 

Keyword: ISAAC

Pure mathematics is, in its way, the poetry of logical ideas.

PVRD MIUGDMIUHAT HT HN HUT XIZ UGD PODURZ OE LOFHAIL HCDIT

200

Decrypt this message, that was encrypted with the keyword cipher

Keyword: ARLIS

BAJV WH JVS ZACUKAUS DT JVS KCWMSGHS. HD, JVS BDGS SFKAJWDCH PDK YCDN, JVS BDGS PDK LAC LDCMSGHS NWJV JVS LDHBDH

Math is the language of the universe. So, the more equations you know, the more you can converse with the cosmos

300

Find the greatest common divisor d of 1929 and 135.

3

300

Give me the cycle structure for a Caesar Cipher with key of a shift of 19.

(A T M F Y R K D W P I B U N G Z S L E X Q J C V O H)

300

Encrypt the following message with rail fence cipher (4)

Just because we can’t find a solution it doesn’t mean that there isn’t one

JCEILINTETUEAWCFNOUNTSTNHHRNOSBUEATDSTODEMAATESNTSNAIOETIE

300

Decrypt this message that used the Rail fence Cipher

WMUSIBNYEHUBATTLKNSEESSMBALYNEEIIISGIEVNHPYUUAERBFLKAWYTOITHNTFRSUEHHNOI

Why are numbers beautiful? It's like asking why is Beethoven's Ninth Symphony beautiful (5)

400

Find the greatest common divisor d of 332 and 87.

1

400

Give me the cycle structure for a keyword cipher with keyword: HEXAGON, continuing the alphabet. 

(A H P Y L T D)(B E G N V I Q Z M U F O W J R)(C X K S)

400

Use a columnar transposition cipher with a full rectangular array and keyword BACKFIRE to encrypt the following message:

Bottomless wonders spring from simple rules which are repeated without end

OSSORCEHBSSREIPTTWPMUHAOERFLHEIDONIIERETMDNMSEDETORSLATULEGPWRWN

400

Cryptanalyze the following message.  It was encrypted with a columnar transposition cipher using a full rectangular array. 

EAOOESMNGLSERSAOHFDNUIFMAOANNSTPSSHGOOAQTNRHNEIUEIXEETUTG

An equation for me has no meaning unless it expresses a thought of God

500

Find the greatest common divisor d of 34924 and 7117

1

500

Decrpyt the ciphertext with the given cycle structure

(A M J F X Y Z E I D R P N K G B)(C T S Q O L H) (U) (V) (W)

Cipher: S C I / G I Z / D Q / X L D K R

Plaintext: the key is foind

500

Encrypt the following using the Vigenere Cipher with keyword ULTRA:


Discovery is something to be cherished.

Xtltoppkp im dhdensbeg nz uv cbpkzsbpw.

500

Decrypt this message, encrypted using the Vigenère Cipher. 

Yezhqqgtugy adi zhq vksgpz or qesfixiayy paakre aniol to ark uzhkrexgnpw, gnp aniol zhq ytcarycusas diiosrotust or fkagxe mgwz pxee az mspavzazx vadx.

Mathematics are the result of mysterious powers which no one understands, and which the unconscious recognition of beauty must play an important part.

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