added a problem, but someone has to get my program running on a server

This commit is contained in:
neptunia 2016-11-15 19:47:06 -05:00
parent 3371d7bc1b
commit 0a31b38383
4 changed files with 42 additions and 0 deletions

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My friend made some sort of encryption service using the Paillier Cryptosystem. Can you get him to encrypt the string `easyctf{3ncrypt_m3!}` for me?
Access his encryption serice at `memes.com:1234` <- fix this later

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#easyctf{3ncrypt_m3!}
p = 8144194198641127053467521063088973929365485175581336279930490759203400725623086153929294542350943040473375790841894343662879542882143670576484983482676929
q = 9349990237178389195581522619084514015305492951423232071317276234453300521753669715890246992825146527366147991960266180184131002960074501683578205688324193
n = p*q
l = (p-1)*(q-1)
g = n+1
mu = 50461441817124067084598541006218828107720370909059246792962232658242869571003990015294541684702084151173329882441771747115542549562899610400402036968340066285127945127930744036805832623326255171902722383305695091973581469008587730106329093915495096858331002656658189454919392650001488548518482449865519307486
m = int(raw_input('Enter a message to encrypt: '))
r = int(raw_input('Enter r (int): '))
if m > 100000000000000000 or m < 0:
print('Bad m. We only take m from 0 to 100000000000000000.')
exit()
if r > 100000000000000000 or r < 0:
print('Bad r. We only take r from 0 to 100000000000000000.')
exit()
c = (pow(g,m,n**2)*pow(r,n,n**2))%(n**2)
print 'c: '+str(c)

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def grade(autogen, answer):
try:
answer = int(answer)
p = 8144194198641127053467521063088973929365485175581336279930490759203400725623086153929294542350943040473375790841894343662879542882143670576484983482676929
q = 9349990237178389195581522619084514015305492951423232071317276234453300521753669715890246992825146527366147991960266180184131002960074501683578205688324193
n = p*q
l = (p-1)*(q-1)
g = n+1
mu = 50461441817124067084598541006218828107720370909059246792962232658242869571003990015294541684702084151173329882441771747115542549562899610400402036968340066285127945127930744036805832623326255171902722383305695091973581469008587730106329093915495096858331002656658189454919392650001488548518482449865519307486
if ((pow(answer,l,n**2)-1)//n * mu)%n == 578781299356711768839252397261103878073419506045:
return True, "Correct!"
return False, "Nope, try again."
except:
return False, "Nope, try again."

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title: Paillier Service
author: neptunia
hint: https://en.wikipedia.org/wiki/Paillier_cryptosystem
category: Cryptography
autogen: false
programming: false
value: 400