CAPTURE THE FLAG

How to Play

  1. Choose any puzzle by clicking on the corresponding box on the webpage. The point values are listed on each box.

  2. Solve the puzzle using critical thinking, logic, and your knowledge of electrical engineering. The answer to the puzzle will always be a password or passphrase.

  3. When you have solved the puzzle, enter the answer into the linked google form. Make sure you are signed in with your USC email, the form will automatically record your email address.

  4. Enter the password or passphrase in the google form. If you are correct, congrats! You have earned some points. If not, the form will not allow you to proceed and you have to try again. You are allowed infinitely many guesses.

 

Additional Rules

  • Working in teams is encouraged! Puzzles are always more fun with friends.  Make sure the same person submits the responses for each puzzle!

  • If you have not done so already, join USC IEEE’s Slack channel!

  • Feel free to message any of the ambassadors on Slack to ask for a hint. Hints will cost you points, however, so use them sparingly!

Puzzle 1

Rough Tough and Huffman

You have come upon a computer game where your possible movement options are the four cardinal directions (up, down, left, and right) plus the four diagonal directions (UL, UR, DL, DR). After some investigation, you come up with the following frequencies for these actions


 

U - 19.7%

D - 17.4%

L - 10.5%

R - 8.3 %

UL - 13.7%

UR - 11.2%

DL - 18.3%

DR - 0.9%

 

All of a sudden, you receive a stream of bits:

101111111000011010011001

Screen Shot 2020-12-26 at 4.37.33 PM.png
 

Puzzle 2

Running away with the key

Help! There is a thief running away with the key to your code! When you catch him, he says the following:

“This is the key, right here, what I am saying right now.”

 

Can you decode the message you have?

 

Tubgvah Vvdier qy h yhrkeoaiv tizwap iymvjxh iecbxzagz.

 

Puzzle 3

Lower the volume, then click 

 
 
 
 

Puzzle 7

065 032 104 097 109 032 115 097 110 100 119 105 099 104 032 119 097 108 107 115 032 105 110 116 111 032 097 032 098 097 114 032 097 110 100 032 111 114 100 101 114 115 032 097 032 098 101 101 114 046 032 084 104 101 032 098 097 114 116 101 110 100 101 114 032 115 097 121 115 044 032 226 128 156 083 111 114 114 121 044 032 119 101 032 100 111 110 226 128 153 116 032 115 101 114 118 101 032 102 111 111 100 032 104 101 114 101 046 226 128 157

Puzzle 8

If a chessboard were to have pennies placed on each square such that one penny was placed on the first square, two pennies were stacked on the second, four pennies were stacked on the third, and so on (doubling the number of pennies on each subsequent square), how many total pennies would be on the chessboard when all squares are filled?

 
 

Puzzle 9

Say you want to make a timer on your Arduino UNO using interrupts. Given that the Arduino UNO clock is fixed at 16 MHz, and you wish to have a delay of 0.1s between cycles, what must your prescaler and OCR1A values be (using the SMALLEST possible prescaler value)?

 

HINT: The prescaler must be one of the following powers of 2: 8, 64, 256, or 1024.

ANOTHER HINT: The OCR1A value you calculate must fit in at most a 16-bit register.

 

Puzzle 10

Use the answer from level one to pick one of the shapes below, using the phrases below as clues

  • Miley cyrus’s sister, ark, stranger things & tiktok star

  • Honda car

  • New york city talkshow

Screen Shot 2020-12-26 at 5.33.22 PM.png
 

Puzzle 11

Solve the word ladder starting with keyword "WHAT"

Screen Shot 2020-12-26 at 4.59.17 PM.png
 

Puzzle 12

Using the code below, find the password.

Input: "jU5t_a_sna_3lpm13gf49_u_4_mar24c"

Screen Shot 2020-12-26 at 6.34.16 PM.png
Screen Shot 2020-12-26 at 6.34.29 PM.png
 

Puzzle 13

The one time pad can be cryptographically secure, but not when you know the key. Can you solve this?

You are given the encrypted flag, key, and a table to help.

Encryption: hgxiofhv iwf mtshluff xyiqxn

Key: uscecedepartment 

Can you use this table to solve it?

HINT: Vigenere cipher problem

Screen Shot 2020-12-26 at 6.41.08 PM.png
 

Puzzle 14

UPDLOAD DATA

You need to upload 650 MBytes of files to the spaceship.

The tablet you are using connects to the spaceship via Bluetooth, which has a data transfer rate of 2.1 Mbits/sec. How long will it take to do this task?

 

Answer in minutes and round to the next whole minute.

 

Puzzle 15

SWIPE CARD

It seems that there is an error on your card! As you take a closer look, you see that the eighth digit in the UPC barcode has been scratched off. Calculate the missing number to complete your task.

Screen Shot 2020-12-26 at 6.46.51 PM.png
 

Puzzle 16

DIVERT POWER

Given the circuit below with a 7.5 V DC power source, which switches do you need to close so that the circuit dissipates 12.5 W of power?

Screen Shot 2020-12-26 at 6.50.01 PM.png
 

Puzzle 17

Find the number of sub-strings with the following properties in the given string:

  1. Length >= 2

  2. Contains only A's

  3. Bound on both sides by either the beginning of the string, the end of the string, or by any character other than a.

 

For example, lets take the string "aabaaacadaa". It contains three such sub-strings, indexes 0-1, 3-5, and 9-10. The sub-string from indexes 3-4 is not valid because it is bound on the right side by an "a". The character with index eight is not valid either, because although it is an "a" and is bounded by the correct characters, it only has a length of one.

The string

caanqaaeamdwaagarapabseaawaabawaoaalaaaaaxxaapsxeaagragaaadawaoaanaawpqatdaaatakwsaaaayaaaaealabjxaaaeaaauamjawnsaataaaoaaqaxaaaaaeaajrahaaaaaadjaaqtewhspaaaaannaoaaaaaboaaaaaaaaaataqadihaaaaqawwaaazoaxaoapabuzwaaaaaaaahlaauakaaiyjavwcaasxaaturabanuataoikpkaoalaaaaaaafgaalwuxzaazaaltazjdaaasalraabaqjmaaadaaaaaaaaiauaqbajaaactaarwrcavmaaxxaqrxaaaaaaaeaaaqaajafaaadaciaaaakadraacafaahlaiaaaakefahalaaparxaaagaacnoraaytaloasaadaaaafataaoqarcazjmqeafajgaaaaaaavvaaaaaiaaaaiaaczrbalomaakgilacaayaayaxwaotaarlaxpaaraapaaaswhxxaajeagfaaaaeaaalaaaaeeaatoamayaaauaadaueccvaauvaakowasxaaatgnwaawtrxtudppfaaqfypaaaaanraiaaaynagqqaabdaayaaazaesasaaaaaaoaaaaacvawcasaiaaaavxafaqeaaadaciaaanujgxamxiaadazanaamaygabwrfazalaaawkpaalsaafiiataatavvaqaqzdatyaaaaanpsaaaajvaydxacyadaolabhocaaawaniniuaaakaaiaaanxaaxaccfaarlaakaabenevaaacaydaaxaaxepasmaasadabanaaafaalaladaagafaaaaaahagnixwemathayfagaxapkaaaafaasaacawaaaaackawamaaaawaatnaaoaaatbaniafawaalkaaumqzaoaauaamazaztamvdaxdaraeasaaaaachoavaaaqaajwaaaaaacarlaxaaapaaaaamfaaoeaoaaamapkacamraalbnavaaaxiaqazaamcmanagaicraawaaascbmraaavabaawaagqataazuaaaaakawxwazparaaaaaaaaasaiedhfaaaetaaaapaaapiaaaawembhmafalgayaaodamqazqwaasdeaappaacaarahnalaeaaaaanasasbzaaaaoaraeaazhaaevoiaazpypuggeayaapanzakaaaavzaacaaraaaaaaaxsvyacoxvttzgtbcuazxkuaaaiflbjzaaojaboxmaadkaaakzsbxaaaajanaatgaaaazarfaawujasaanxazowlfaayahaaaaaabdoayufltoaiabayaaafawiazaqaasaafchifgpjuvauaaayaaatvaxaaeaaharrazavlayaaaaaaagxcfaemvyaaaaaaulxajahazgapaasagswmahaapbaaafnaaywpagqiauaaaavbmgifaweatvaayhaadajaaaaragaminaafixwuaaexaajawzaazlaxastaatmdaaaaairfnraaaaaaaxaafgaattgakkaacioaabatahfqabmvzfzafifsbbnaaouaahalaahuaawaagataamarjgaaaamianabhaaaaaaiahtpxvaaaaaaahaahtgaaaazvafaaaavzkamalawaaqeaaaavgjkanenairaalazaaaayafsazaacodeawvamtdyaaaynaaxaazvssadaqdvstaaolcsecwszzaajahawajooaahgumavaabriwaazgrtaauaxpaaawbhaberaqltaaaaqaaaaxayldaaxgakmwmaaxxayualfaaijsaaaazxpaaaewcngnaaaypvmayaiaamaasaaakattsadqclclafadaaaadsnwdnaaqasataabasaataaaapajqatuakaygaaoamatgaacaaaaaljwzaaaqajafanaaxaagxqaaibgaslawuadeaaxbaweaxxaaaaesnaacatahaitatqsabkaaaaatlajpavaaadlnvzaeaascaaaahqmatanapciszqefcalacjraamhaaaaoanaganaaaaacaqcnaayaawaagazaayyaayjagasarbuafzpmpqeaohaaaglidaanrheaaaabnnaairalrbjuzaakaabgaeaadaaetaauaaaaazaadzxaaaagavazehulaauazvcaajcaaaaqgexaaaaajcirxauaahaoaaahohaanaayoaalukbaauaaaaioaaakcobkoaqdvalasraaawuaakaaaaaadamsaaaaaqakaanaxaaaiwaodazaanaaaravbqimznaataaesaavyqjakgabaeaiasamapaaaalwzaikpbclaaaacalakusaapaaaaqnaanaaahoaaaecaarwwaaaabxaaaaaepalaaaaaaaxaxgamawmalaaaaanqeaaaaxaomajaaaiavaaqxwaazaaaaaaaaapqpaaaaaastgdydwxaalahaiziaamauayaqaxyryaizkaefuaaaaaaaeaaanaaiaaaaayaaaaaaiywaaahaaaaajtawmanmadayaaawaaaaxagaaicaiagaaanaaakaodapaaaaabaaaaaadauevaaywbaaaaaaaaaaygaaawaazimwasraazoagvzpaabrnmlhqghhoaaanbaaanaaaaaqxauaaataaaabaahaaaafzaawaapaaaaaarazalqhobgzacazasauaaaaaujafowabywlaagaaadaaatamaaagnpmaeaaaaahmmxapanaraagsxoutbaaaauaqamlazaaaaaaaazaalnsacxltaavaaxpldaqqhapasmalaasutapuasaaatuloaaadaizmaaaaaqqyalyopwakaayhvyaaaczjeauavauxypyenmaaqiaaqiaahuaaakaauja