Problem 1: Substution Cipher Decryption

Break the letter-substitution cipher shown here:

LESTX KQLEY TQOJX ZEHYT QJQKL IQHST XAALY EXYSE SRYPH LJYPG QYTXK QVLKK QHGLY TYTQQ EHRXV GXJBR SEHSE XXFPR BQKKE XJPQY SHJPA SJQRS EHPTX KQGLY TEXYT LEOLE LYYXR LYHXG EXEXJ YXQSY LYGSR STXAA LYTXK QSEHY TSYBQ SERDX BVXJY

Hints:

This is actually quite challenging to do without a program to help, though you could start looking for letter combinations (such as double-letters or common English characters that are often near each other). But, to help out, the following is the output from the following python script:

#!/usr/bin/env python3
import itertools
import re

WORDLIST = "top-words.txt"

ENGLISH_FREQS = (
    ('E', 0.127),
    ('T', 0.091),
    ('A', 0.082),
    ('O', 0.075),
    ('I', 0.07),
    ('N', 0.067),
    ('S', 0.063),
    ('H', 0.061),
    ('R', 0.06),
    ('D', 0.043),
    ('L', 0.04),
    ('C', 0.028),
    ('U', 0.028),
    ('M', 0.024),
    ('W', 0.024),
    ('F', 0.022),
    ('G', 0.02),
    ('Y', 0.02),
    ('P', 0.019),
    ('B', 0.015),
    ('V', 0.0098),
    ('K', 0.0077),
    ('J', 0.0015),
    ('X', 0.0015),
    ('Q', 0.00095),
    ('Z', 0.00074),
)

def main():
    ciphertext = 'LESTX KQLEY TQOJX ZEHYT QJQKL IQHST XAALY EXYSE SRYPH LJYPG QYTXK QVLKK QHGLY TYTQQ EHRXV GXJBR SEHSE XXFPR BQKKE XJPQY SHJPA SJQRS EHPTX KQGLY TEXYT LEOLE LYYXR LYHXG EXEXJ YXQSY LYGSR STXAA LYTXK QSEHY TSYBQ SERDX BVXJY' 

    freqs = get_frequencies(ciphertext)
    sorted_freqs = get_sorted_freqs(freqs)
    """
    for letter, freq in sorted_freqs:
        print(f"{letter}\t{freq}")
    
    for ch, freq in sorted_freqs:
        print(f"{ch}: {freq}")
    """
    permute_top_ten(ciphertext.replace(' ', ''), sorted_freqs, ENGLISH_FREQS)

    # try_finding_THE(ciphertext, sorted_freqs)

def get_frequencies(text):
    freqs = {}
    for ch in text:
        if ch != ' ':
            if ch not in freqs:
                freqs[ch] = 1
            else:
                freqs[ch] += 1
    # normalize
    for ch in freqs:
        freqs[ch] = round(freqs[ch] / len(text), 4)
    return freqs

def get_sorted_freqs(freqs):
    return sorted([(k, v) for k, v in freqs.items()], key=lambda x: x[1], reverse=True)

def permute_top_ten(text, sorted_freqs, english_freqs):
    perms = itertools.permutations(sorted_freqs[:10])
    max_word_matches = 0
    with open(WORDLIST) as f:
        TOP_1000_WORDS = set([x[:-1].upper() for x in f.readlines()])
    for idx, perm in enumerate(perms):
        """
        if idx % 10000 == 0:
            print(f"count: {idx}")
        elif idx % 1000 == 0:
            print(".", end='', flush=True)
        """
        perm = [x[0] for x in perm]
        full_perm = perm + [x[0] for x in sorted_freqs[10:]]
        key_dict = {}
        for idx2, ch in enumerate(full_perm):
            key_dict[ch] = english_freqs[idx2][0]
        plaintext = decrypt(text, key_dict)
        """
        if idx == 20164:
            word_matches = total_word_matches(TOP_1000_WORDS, plaintext, Print=True)
            breakpoint()
        """
            
        word_matches = total_word_matches(TOP_1000_WORDS, plaintext)
        if word_matches >= max_word_matches:
            max_word_matches = word_matches
            print(f"word matches: {word_matches}")
            print(plaintext)
            total_word_matches(TOP_1000_WORDS, plaintext, Print=True)
            print()

def decrypt(text, key_dict):
    plaintext = ''
    for ch in text:
        plaintext += key_dict[ch]
    return plaintext


def total_word_matches(wordlist, text, min_length=2, max_length=14, Print=False):
    word_count = 0
    for i in range(len(text)):
        for j in range(min_length, max_length):
            if i + j > len(text):
                break
            test_word = text[i:i + j]
            if test_word in wordlist:
                word_count += 1
                if Print:
                    print(f"{test_word},", end='')
    if Print:
        print()
    return word_count

if __name__ == "__main__":
    main()

The code is actually quite slow, and requires this English word file that has over 6000 common English words in it.
Here is a faster version of the program, written in C++. If you have a C++ compiler, such as clang++, you can compile it like this:
```
clang++ -O3 -march=native -DNDEBUG decryptP1.cpp -o decryptP1
```

Here is the output of the program:

word matches: 24
NAISTRONAESOGDTYAHESODORNPOHISTMMNEATEIAILECHNDECUOESTROFNRROHUNESESOOAHLTFUTDWLIAHIATTBCLWORRATDCOEIHDCMIDOLIAHCSTROUNESATESNAGNANEETLNEHTUATATDETOIENEUILISTMMNESTROIAHESIEWOIALVTWFTDE
IST,RON,ON,SO,SO,HIS,HIST,IST,EAT,ATE,OF,SO,RAT,MID,IDOL,SAT,ATE,AN,ATA,TO,LIST,IST,NEST,SIE,

word matches: 27
NAISTHONAESOGDTYARESODOHNPORISTMMNEATEIAILECRNDECUOESTHOFNHHORUNESESOOARLTFUTDWLIARIATTBCLWOHHATDCOEIRDCMIDOLIARCSTHOUNESATESNAGNANEETLNERTUATATDETOIENEUILISTMMNESTHOIARESIEWOIALVTWFTDE
IST,HON,ON,SO,ARE,SO,IST,EAT,ATE,OF,RUN,SO,HAT,MID,IDOL,ARC,THOU,SAT,ATE,AN,ATA,TO,LIST,IST,NEST,ARE,SIE,

word matches: 30
NAIDTSONAEDOGHTYAREDOHOSNPORIDTMMNEATEIAILECRNHECUOEDTSOFNSSORUNEDEDOOARLTFUTHWLIARIATTBCLWOSSATHCOEIRHCMIHOLIARCDTSOUNEDATEDNAGNANEETLNERTUATATHETOIENEUILIDTMMNEDTSOIAREDIEWOIALVTWFTHE
AID,SO,SON,ON,DOG,ARE,RED,RID,EAT,ATE,SO,OF,SO,RUN,SAT,ARC,SO,DATE,ATE,TED,AN,ATA,THE,TO,LID,SO,ARE,RED,DIE,THE,

word matches: 32
NAIDTHONAEDOGSTYAREDOSOHNPORIDTMMNEATEIAILECRNSECUOEDTHOFNHHORUNEDEDOOARLTFUTSWLIARIATTBCLWOHHATSCOEIRSCMISOLIARCDTHOUNEDATEDNAGNANEETLNERTUATATSETOIENEUILIDTMMNEDTHOIAREDIEWOIALVTWFTSE
AID,HON,ON,DOG,DOGS,ARE,RED,DOS,SO,RID,EAT,ATE,SEC,OF,RUN,HAT,ISO,SO,SOL,ARC,THOU,DATE,ATE,TED,AN,ATA,SET,TO,LID,ARE,RED,DIE,

word matches: 34
SAINTHOSAENOGDTYARENODOHSPORINTMMSEATEIAILECRSDECUOENTHOFSHHORUSENENOOARLTFUTDWLIARIATTBCLWOHHATDCOEIRDCMIDOLIARCNTHOUSENATENSAGSASEETLSERTUATATDETOIESEUILINTMMSENTHOIARENIEWOIALVTWFTDE
SAINT,IN,NO,ARE,NO,IN,SEA,SEAT,EAT,ATE,OF,USE,SEN,NO,HAT,MID,IDOL,ARC,THOU,HOUSE,USE,SEN,SENATE,NAT,ATE,TEN,SEE,SER,ATA,TO,IN,SEN,SENT,ARE,

word matches: 34
SAINTDOSAENOGHTYARENOHODSPORINTMMSEATEIAILECRSHECUOENTDOFSDDORUSENENOOARLTFUTHWLIARIATTBCLWODDATHCOEIRHCMIHOLIARCNTDOUSENATENSAGSASEETLSERTUATATHETOIESEUILINTMMSENTDOIARENIEWOIALVTWFTHE
SAINT,IN,DOS,NO,ARE,NO,IN,SEA,SEAT,EAT,ATE,SHE,OF,USE,SEN,NO,ODD,ARC,USE,SEN,SENATE,NAT,ATE,TEN,SEE,SER,ATA,THE,TO,IN,SEN,SENT,ARE,THE,

word matches: 34
SAINTROSAENOGHTYADENOHORSPODINTMMSEATEIAILECDSHECUOENTROFSRRODUSENENOOADLTFUTHWLIADIATTBCLWORRATHCOEIDHCMIHOLIADCNTROUSENATENSAGSASEETLSEDTUATATHETOIESEUILINTMMSENTROIADENIEWOIALVTWFTHE
SAINT,IN,ROSA,NO,DEN,NO,POD,IN,SEA,SEAT,EAT,ATE,SHE,OF,ROD,USE,SEN,NO,RAT,USE,SEN,SENATE,NAT,ATE,TEN,SEE,ATA,THE,TO,IN,SEN,SENT,DEN,THE,

word matches: 41
SAIRTHOSAEROGDTYANERODOHSPONIRTMMSEATEIAILECNSDECUOERTHOFSHHONUSEREROOANLTFUTDWLIANIATTBCLWOHHATDCOEINDCMIDOLIANCRTHOUSERATERSAGSASEETLSENTUATATDETOIESEUILIRTMMSERTHOIANERIEWOIALVTWFTDE
AIR,AN,ROD,ON,SEA,SEAT,EAT,ATE,OF,HON,ON,USE,USER,SER,AN,IAN,AN,HAT,IN,IND,MID,IDOL,IAN,AN,THOU,HOUSE,USE,USER,SER,ERA,RAT,RATE,ATE,SEE,SEN,SENT,ATA,TO,SER,IAN,AN,

word matches: 41
RAIDTSORAEDOGHTYANEDOHOSRPONIDTMMREATEIAILECNRHECUOEDTSOFRSSONUREDEDOOANLTFUTHWLIANIATTBCLWOSSATHCOEINHCMIHOLIANCDTSOUREDATEDRAGRAREETLRENTUATATHETOIEREUILIDTMMREDTSOIANEDIEWOIALVTWFTHE
RAID,AID,SO,DOG,AN,ON,EAT,ATE,SO,OF,SO,SON,ON,RED,AN,IAN,AN,SAT,IN,IAN,AN,SO,OUR,RED,DATE,ATE,TED,DRAG,RARE,ARE,RENT,ATA,THE,TO,LID,RED,SO,IAN,AN,DIE,THE,

word matches: 44
RAIDTHORAEDOGSTYANEDOSOHRPONIDTMMREATEIAILECNRSECUOEDTHOFRHHONUREDEDOOANLTFUTSWLIANIATTBCLWOHHATSCOEINSCMISOLIANCDTHOUREDATEDRAGRAREETLRENTUATATSETOIEREUILIDTMMREDTHOIANEDIEWOIALVTWFTSE
RAID,AID,DOG,DOGS,AN,DOS,SO,ON,EAT,ATE,SEC,OF,HON,ON,RED,AN,IAN,AN,HAT,IN,ISO,SO,SOL,IAN,AN,THOU,HOUR,OUR,RED,DATE,ATE,TED,DRAG,RARE,ARE,RENT,ATA,SET,TO,LID,RED,IAN,AN,DIE,

word matches: 44
RANDTSORAEDOGHTYAIEDOHOSRPOINDTMMREATENANLECIRHECUOEDTSOFRSSOIUREDEDOOAILTFUTHWLNAINATTBCLWOSSATHCOENIHCMNHOLNAICDTSOUREDATEDRAGRAREETLREITUATATHETONEREUNLNDTMMREDTSONAIEDNEWONALVTWFTHE
RAN,RAND,AN,AND,SO,DOG,IN,IND,EAT,ATE,TEN,AN,SO,OF,SO,RED,IN,NAT,SAT,SO,OUR,RED,DATE,ATE,TED,DRAG,RARE,ARE,ATA,THE,TO,TON,TONE,TONER,ON,ONE,RED,SO,SON,ON,NEW,WON,ON,THE,

word matches: 46
RANDTHORAEDOGSTYAIEDOSOHRPOINDTMMREATENANLECIRSECUOEDTHOFRHHOIUREDEDOOAILTFUTSWLNAINATTBCLWOHHATSCOENISCMNSOLNAICDTHOUREDATEDRAGRAREETLREITUATATSETONEREUNLNDTMMREDTHONAIEDNEWONALVTWFTSE
RAN,RAND,AN,AND,DOG,DOGS,DOS,SO,IN,IND,EAT,ATE,TEN,AN,SEC,OF,RED,IN,NAT,HAT,SO,SOL,THOU,HOUR,OUR,RED,DATE,ATE,TED,DRAG,RARE,ARE,ATA,SET,TO,TON,TONE,TONER,ON,ONE,RED,HON,ON,NEW,WON,ON,

word matches: 46
SANDTHOSAEDOGITYAREDOIOHSPORNDTMMSEATENANLECRSIECUOEDTHOFSHHORUSEDEDOOARLTFUTIWLNARNATTBCLWOHHATICOENRICMNIOLNARCDTHOUSEDATEDSAGSASEETLSERTUATATIETONESEUNLNDTMMSEDTHONAREDNEWONALVTWFTIE
SAN,SAND,AN,AND,DOG,ARE,RED,SEA,SEAT,EAT,ATE,TEN,AN,SIE,OF,USE,USED,NAT,HAT,ATI,ARC,THOU,HOUSE,USE,USED,DATE,ATE,TED,SEE,SER,ATA,ATI,TIE,TO,TON,TONE,ON,ONE,HON,ON,ARE,RED,NEW,WON,ON,TIE,

word matches: 46
SADRTHOSAEROGITYANEROIOHSPONDRTMMSEATEDADLECNSIECUOERTHOFSHHONUSEREROOANLTFUTIWLDANDATTBCLWOHHATICOEDNICMDIOLDANCRTHOUSERATERSAGSASEETLSENTUATATIETODESEUDLDRTMMSERTHODANERDEWODALVTWFTIE
SAD,AN,POND,ON,SEA,SEAT,EAT,ATE,TED,DAD,SIE,OF,HON,ON,USE,USER,SER,AN,DAN,AN,AND,HAT,ATI,OLD,DAN,AN,THOU,HOUSE,USE,USER,SER,ERA,RAT,RATE,ATE,SEE,SEN,SENT,ATA,ATI,TIE,TO,SER,DAN,AN,TIE,

word matches: 48
SADRTOISAERIGHTYANERIHIOSPINDRTMMSEATEDADLECNSHECUIERTOIFSOOINUSERERIIANLTFUTHWLDANDATTBCLWIOOATHCIEDNHCMDHILDANCRTOIUSERATERSAGSASEETLSENTUATATHETIDESEUDLDRTMMSERTOIDANERDEWIDALVTWFTHE
SAD,TO,RIGHT,AN,SPIN,PIN,IN,IND,SEA,SEAT,EAT,ATE,TED,DAD,SHE,TO,SO,IN,USE,USER,SER,IAN,AN,DAN,AN,AND,DAN,AN,TO,USE,USER,SER,ERA,RAT,RATE,ATE,SEE,SEN,SENT,ATA,THE,TIDE,IDE,SER,TO,DAN,AN,THE,

word matches: 49
SADHTRISAEHIGOTYANEHIOIRSPINDHTMMSEATEDADLECNSOECUIEHTRIFSRRINUSEHEHIIANLTFUTOWLDANDATTBCLWIRRATOCIEDNOCMDOILDANCHTRIUSEHATEHSAGSASEETLSENTUATATOETIDESEUDLDHTMMSEHTRIDANEHDEWIDALVTWFTOE
SAD,TRI,GOT,AN,SPIN,PIN,IN,IND,SEA,SEAT,EAT,ATE,TED,DAD,SO,TRI,IN,USE,IAN,AN,TO,DAN,AN,AND,RAT,TO,NO,OIL,DAN,AN,TRI,USE,HAT,HATE,ATE,SEE,SEN,SENT,ATA,TO,TOE,TIDE,IDE,TRI,RID,DAN,AN,TO,TOE,

word matches: 49
SARDTHISAEDIGOTYANEDIOIHSPINRDTMMSEATERARLECNSOECUIEDTHIFSHHINUSEDEDIIANLTFUTOWLRANRATTBCLWIHHATOCIERNOCMROILRANCDTHIUSEDATEDSAGSASEETLSENTUATATOETIRESEURLRDTMMSEDTHIRANEDREWIRALVTWFTOE
THIS,HIS,DIG,GOT,AN,SPIN,PIN,IN,SEA,SEAT,EAT,ATE,ERA,SO,IN,USE,USED,IAN,AN,TO,RAN,AN,RAT,HAT,TO,NO,OIL,RAN,AN,USE,USED,DATE,ATE,TED,SEE,SEN,SENT,ATA,TO,TOE,TIRE,IRA,IRAN,RAN,AN,DREW,IRA,TO,TOE,

word matches: 53
SADRTHISAERIGOTYANERIOIHSPINDRTMMSEATEDADLECNSOECUIERTHIFSHHINUSERERIIANLTFUTOWLDANDATTBCLWIHHATOCIEDNOCMDOILDANCRTHIUSERATERSAGSASEETLSENTUATATOETIDESEUDLDRTMMSERTHIDANERDEWIDALVTWFTOE
SAD,THIS,HIS,GOT,AN,RIO,SPIN,PIN,IN,IND,SEA,SEAT,EAT,ATE,TED,DAD,SO,IN,USE,USER,SER,IAN,AN,TO,DAN,AN,AND,HAT,TO,NO,OIL,DAN,AN,USE,USER,SER,ERA,RAT,RATE,ATE,SEE,SEN,SENT,ATA,TO,TOE,TIDE,IDE,SER,DAN,AN,TO,TOE,

word matches: 56
SIRATONSIEANGHTYIDEANHNOSPNDRATMMSEITERIRLECDSHECUNEATONFSOONDUSEAEANNIDLTFUTHWLRIDRITTBCLWNOOITHCNERDHCMRHNLRIDCATONUSEAITEASIGSISEETLSEDTUITITHETNRESEURLRATMMSEATONRIDEAREWNRILVTWFTHE
SIR,IRA,RAT,TO,TON,ON,ONS,SIE,AN,IDE,IDEA,DEAN,AN,NO,RAT,SHE,EAT,TO,TON,ON,SO,SOON,ON,USE,SEA,AN,ANN,RID,NO,RID,CAT,TO,TON,ON,USE,SEA,TEA,SIG,SEE,TIT,THE,RAT,SEA,SEAT,EAT,TO,TON,ON,RID,RIDE,IDE,IDEA,DEAR,EAR,ARE,THE,

word matches: 57
STIRODASTERAGNOYTHERANADSPAHIROMMSETOEITILECHSNECUAERODAFSDDAHUSERERAATHLOFUONWLITHITOOBCLWADDTONCAEIHNCMINALITHCRODAUSERTOERSTGSTSEEOLSEHOUTOTONEOAIESEUILIROMMSERODAITHERIEWAITLVOWFONE
ROD,DAS,ERA,NO,THE,HER,ERA,RAN,AN,ANA,SPA,SET,TO,TOE,TIL,TILE,ROD,USE,USER,SER,ERA,OF,ON,LIT,HIT,TO,TOO,ADD,TO,TON,ON,MIN,IN,LIT,ROD,AUS,USE,USER,SER,TO,TOE,SEE,OUT,TO,TO,TON,TONE,ON,ONE,NEO,SER,ROD,THE,HER,WAIT,ON,ONE,

word matches: 59
HTARODSHTERSGNOYTIERSNSDHPSIAROMMHETOEATALECIHNECUSERODSFHDDSIUHERERSSTILOFUONWLATIATOOBCLWSDDTONCSEAINCMANSLATICRODSUHERTOERHTGHTHEEOLHEIOUTOTONEOSAEHEUALAROMMHERODSATIERAEWSATLVOWFONE
TAR,ROD,NO,TIE,TIER,PSI,TO,TOE,EAT,ATA,TALE,USE,USER,SER,ROD,HER,HERE,TIL,OF,ON,LAT,ATI,TO,TOO,TO,TON,ON,SEA,IN,MAN,AN,LAT,ATI,ROD,HER,TO,TOE,THE,THEE,OUT,TO,TO,TON,TONE,ON,ONE,NEO,ALA,HER,HERO,ROD,SAT,ATI,TIE,TIER,ERA,SAT,ON,ONE,

word matches: 61
STARODHSTERHGNOYTIERHNHDSPHIAROMMSETOEATALECISNECUHERODHFSDDHIUSERERHHTILOFUONWLATIATOOBCLWHDDTONCHEAINCMANHLATICRODHUSERTOERSTGSTSEEOLSEIOUTOTONEOHAESEUALAROMMSERODHATIERAEWHATLVOWFONE
STAR,TAR,ROD,NO,TIE,TIER,PHI,SET,TO,TOE,EAT,ATA,TALE,HER,HERO,ROD,USE,USER,SER,TIL,OF,ON,LAT,ATI,TO,TOO,TO,TON,ON,IN,MAN,AN,LAT,ATI,ROD,USE,USER,SER,TO,TOE,SEE,OUT,TO,TO,TON,TONE,ON,ONE,NEO,ALA,SER,ROD,HAT,ATI,TIE,TIER,ERA,WHAT,HAT,ON,ONE,

word matches: 64
SIRANOTSIEATGHNYIDEATHTOSPTDRANMMSEINERIRLECDSHECUTEANOTFSOOTDUSEAEATTIDLNFUNHWLRIDRINNBCLWTOOINHCTERDHCMRHTLRIDCANOTUSEAINEASIGSISEENLSEDNUININHENTRESEURLRANMMSEANOTRIDEAREWTRILVNWFNHE
SIR,IRA,IRAN,RAN,AN,NO,NOT,SIE,EAT,IDE,IDEA,DEATH,EAT,TO,RAN,AN,IN,SHE,CUT,CUTE,TEA,AN,NO,NOT,SO,USE,SEA,EAT,FUN,RID,IN,INN,TO,TOO,IN,RID,CAN,AN,NO,NOT,USE,SEA,IN,SIG,SEE,SEEN,IN,IN,RAN,AN,SEA,SEAN,AN,NO,NOT,TRI,RID,RIDE,IDE,IDEA,DEAR,EAR,ARE,TRI,

word matches: 67
INASODEINTSEGROYNHTSEREDIPEHASOMMITNOTANALTCHIRTCUETSODEFIDDEHUITSTSEENHLOFUORWLANHANOOBCLWEDDNORCETAHRCMARELANHCSODEUITSNOTSINGINITTOLITHOUNONORTOEATITUALASOMMITSODEANHTSATWEANLVOWFORT
IN,SO,IN,ROY,SER,RED,DIP,SO,NO,NOT,TAN,AN,ANA,ALT,CHI,SO,ITS,SEE,SEEN,OF,LAN,AN,AN,NO,WE,WED,NO,NOR,MAR,ARE,REL,LAN,AN,SO,ITS,NO,NOT,SIN,SING,IN,ING,IN,TO,LIT,THOU,NO,NON,ON,NO,NOR,TO,TOE,EAT,ATI,TIT,ALA,LAS,SO,ITS,SO,DEAN,AN,SAT,WE,AN,FOR,FORT,

word matches: 71
INASOHEINTSEGROYNDTSEREHIPEDASOMMITNOTANALTCDIRTCUETSOHEFIHHEDUITSTSEENDLOFUORWLANDANOOBCLWEHHNORCETADRCMARELANDCSOHEUITSNOTSINGINITTOLITDOUNONORTOEATITUALASOMMITSOHEANDTSATWEANLVOWFORT
IN,SO,IN,ROY,SER,HIP,DAS,SO,NO,NOT,TAN,AN,ANA,ALT,DIRT,SO,ITS,SEE,SEEN,END,OF,LAN,LAND,AN,AND,DAN,AN,NO,WE,NO,NOR,MAR,ARE,REL,LAN,LAND,AN,AND,SO,ITS,NO,NOT,SIN,SING,IN,ING,IN,TO,LIT,NO,NON,ON,NO,NOR,TO,TOE,EAT,ATI,TIT,ALA,LAS,SO,ITS,SO,AN,AND,SAT,WE,AN,FOR,FORT,

word matches: 76
INAHOSEINTHEGROYNDTHERESIPEDAHOMMITNOTANALTCDIRTCUETHOSEFISSEDUITHTHEENDLOFUORWLANDANOOBCLWESSNORCETADRCMARELANDCHOSEUITHNOTHINGINITTOLITDOUNONORTOEATITUALAHOMMITHOSEANDTHATWEANLVOWFORT
IN,HOSE,IN,THE,ROY,THE,THERE,HER,HERE,SIP,NO,NOT,TAN,AN,ANA,ALT,DIRT,THOSE,HOSE,THE,THEE,END,OF,LAN,LAND,AN,AND,DAN,AN,NO,WE,NO,NOR,MAR,ARE,REL,LAN,LAND,AN,AND,CHO,CHOSE,HOSE,NO,NOT,NOTHING,THIN,THING,IN,ING,IN,TO,LIT,NO,NON,ON,NO,NOR,TO,TOE,EAT,ATI,TIT,ALA,THOSE,HOSE,SEA,SEAN,AN,AND,THAT,HAT,WE,AN,FOR,FORT,

The output reveals some words that you can use to start the decryption process. Once you have some of the letters, you can iteratively work to get the rest.
The most common letter in the ciphertext does not correspond to E.
Remember, there are no spaces in the ciphertext – the 5-letter “words” above are simply to make it easier to copy. In other words, you can think of the above ciphertext as one long line of characters.

Problem 2: Transposition Cipher Decryption

a. Read the Wikipedia article on transposition ciphers, recreated here.

b. Decipher the following message, which is encrypted using a “Route Cipher” with the following features:

The 70-character plaintext was written into a 10-wide and 7-high grid
It was encrypted with the pattern, “starting at the bottom left, read letters diagonally down and to the right. After reading a diagonal, start at the next row up, and read it down and to the right, etc.”

DUDEN EEVAS ETERE GVYRO RNIEO GUTEV RUONY VEGDN DOEYO ONAUR ONWAN GUNNR OUANN PLNNA

Hint: Start by creating a grid of 10 across and 7 down, and then read off the ciphertext into the grid. Without a grid, this is tricky to get correct! (A spreadsheet works well for this)

Assignment 4

Cryptography

Problem 1: Substution Cipher Decryption

Problem 2: Transposition Cipher Decryption