To compile

g++ hello.c++

To Run

./a.out

Program Notes

1. frequency analysis occurs automatically upon program launchin a table mapping characters to their frequency

2. Various key permutations are tried via swapping characters with the keys to the left and right, and the program outputs the best key and begins accepting input (either swaps or a new key).

3. An option will be prompted to the user if they would like to enter a full key at any point, entering the proper 26 alphabetical key will result in a decrypted text, or the ability to swap an out of place letter for a different one.

4. The key is the plaintext mapping to an ordered ciphertext (aka: index 0 of the key maps to ciphertext A).

How we decrypted the message manually:

1. Start with key: DHIKNVTRUXAMPCYFSGEZOBJWQL and text = THEWOITELSTATESFASATMEADEFITHTHATOATINOAOLATTHESNUIDITATINONGJAMAOFASSTIUUIODNOBERSATINOFITHITSYNBEROCEOTAOLITSECMERNRUNNKIOYTNFARLTHECAIOTEOAODENGMEADEIOTHEMADIGIDIOLEELNOEHNWRAGTERJAMAOESEAIRSZWALRNOSHALDNCCEODELVNCVIOYIONAHWTHEJAMAOESEACVASSALNRTNTHEWOITELSTATESAOLHISDNUUEAYWELEUIBERELTNTHESEDRETARPNGSTATEAGNRCAUREMUPTNAREDEOTACERIDAOCESSAYEFHIUETHISREMUPSTATELTHATITSEECELWSEUESSTNDNOTIOWETHEEXISTIOYLIMUNCATIDOEYNTIATINOSITDNOTAIOELONTHREATNRHIOTNGFARNRARCELATTADK
2. Complete the following swaps:
   • F for W
   • F for U
   • O for N
   • L for D
   • M for P
   • L for C
   • B for V
   • F for L
   • G for F
   • Y for G
   • Y for M
   • Z for Q
3. Final key: CHIKOBTRLXAPYMGWSFEQNVJUZD and plaintext: THEUNITEDSTATESWASATPEACEWITHTHATNATIONANDATTHESOLICITATIONOFJAPANWASSTILLINCONVERSATIONWITHITSGOVERNMENTANDITSEMPERORLOOKINGTOWARDTHEMAINTENANCEOFPEACEINTHEPACIFICINDEEDONEHOURAFTERJAPANESEAIRSQUADRONSHADCOMMENCEDBOMBINGINOAHUTHEJAPANESEAMBASSADORTOTHEUNITEDSTATESANDHISCOLLEAGUEDELIVEREDTOTHESECRETARYOFSTATEAFORMALREPLYTOARECENTAMERICANMESSAGEWHILETHISREPLYSTATEDTHATITSEEMEDUSELESSTOCONTINUETHEEXISTINGDIPLOMATICNEGOTIATIONSITCONTAINEDNOTHREATORHINTOFWARORARMEDATTACK