[Net-Force] [Cryptography] 2. Substitution....

문제 제목에서 냄새가 난다.

대체 암호에 관련된 문제로 추측된다.

문제에서 시작 문자열을 줬으므로, leuk he zo`n으로 맞춰주자.

 
encoded = "ogrk hg tl`n srbszizrzig aiphgu "
encoded += "mg ycahzylluf vllu fg ahcoogneg "
encoded += "pceinc is ngzdluag"
 
# ogrk hg tl`n -> leuk he zo`n
encoded = encoded.replace('o', 'L').replace('g', 'E').replace('u', 'R').replace('e', 'G').replace('t', 'Z').replace('l', 'O')
 
print encoded

r과 z를 치환해주자.

 
encoded = "ogrk hg tl`n srbszizrzig aiphgu "
encoded += "mg ycahzylluf vllu fg ahcoogneg "
encoded += "pceinc is ngzdluag"
 
# ogrk hg tl`n -> leuk he zo`n
encoded = encoded.replace('o', 'L').replace('g', 'E').replace('u', 'R').replace('e', 'G').replace('t', 'Z').replace('l', 'O')
 
# srbsz -> subst
encoded = encoded.replace('r', 'U').replace('z', 'T')
 
print encoded

제대로 배치되어 있는 문자를 대문자로 치환하자.

 
encoded = "ogrk hg tl`n srbszizrzig aiphgu "
encoded += "mg ycahzylluf vllu fg ahcoogneg "
encoded += "pceinc is ngzdluag"
 
# ogrk hg tl`n -> leuk he zo`n
encoded = encoded.replace('o', 'L').replace('g', 'E').replace('u', 'R').replace('e', 'G').replace('t', 'Z').replace('l', 'O')
 
# srbsz -> subst
encoded = encoded.replace('r', 'U').replace('z', 'T')
 
# to uppercase
encoded = encoded.replace('k', 'K').replace('h', 'H').replace('n', 'N').replace('s', 'S').replace('i', 'I').replace('b', 'B')
 
print encoded

aIpHER, CHcLLENGE를 각각 아는 단어로 바꿔주자.

 
encoded = "ogrk hg tl`n srbszizrzig aiphgu "
encoded += "mg ycahzylluf vllu fg ahcoogneg "
encoded += "pceinc is ngzdluag"
 
# ogrk hg tl`n -> leuk he zo`n
encoded = encoded.replace('o', 'L').replace('g', 'E').replace('u', 'R').replace('e', 'G').replace('t', 'Z').replace('l', 'O')
 
# srbsz -> subst
encoded = encoded.replace('r', 'U').replace('z', 'T')
 
# to uppercase
encoded = encoded.replace('k', 'K').replace('h', 'H').replace('n', 'N').replace('s', 'S').replace('i', 'I').replace('b', 'B')
 
# aIpHER -> CIPHER, CHcLLENGE -> CHALLENGE
 
encoded = encoded.replace('a', 'C').replace('c', 'A').replace('p', 'P')
 
print encoded

여태까지의 규칙을 보면, 알파벳이 서로 바뀌는 모습을 볼 수 있다. 

예컨대, o가 l로, l이 o로 바뀌는 것이다.

마지막으로 d와 f를 서로 바꿔주면, 마지막 단어가 패스워드가 된다.

 
encoded = "ogrk hg tl`n srbszizrzig aiphgu "
encoded += "mg ycahzylluf vllu fg ahcoogneg "
encoded += "pceinc is ngzdluag"
 
# ogrk hg tl`n -> leuk he zo`n
encoded = encoded.replace('o', 'L').replace('g', 'E').replace('u', 'R').replace('e', 'G').replace('t', 'Z').replace('l', 'O')
 
# srbsz -> subst
encoded = encoded.replace('r', 'U').replace('z', 'T')
 
# to uppercase
encoded = encoded.replace('k', 'K').replace('h', 'H').replace('n', 'N').replace('s', 'S').replace('i', 'I').replace('b', 'B')
 
# aIpHER -> CIPHER, CHcLLENGE -> CHALLENGE
 
encoded = encoded.replace('a', 'C').replace('c', 'A').replace('p', 'P')
 
# d -> F, f -> D
 
encoded = encoded.replace('d', 'F').replace('f', 'D')
 
print encoded