From 0a31b38383c87de972e4bed142fed182b4443f49 Mon Sep 17 00:00:00 2001
From: neptunia <kevinshen100@gmail.com>
Date: Tue, 15 Nov 2016 19:47:06 -0500
Subject: [PATCH] added a problem, but someone has to get my program running on
 a server

---
 paillier-service/description.md |  3 +++
 paillier-service/encrypt.py     | 17 +++++++++++++++++
 paillier-service/grader.py      | 14 ++++++++++++++
 paillier-service/problem.yml    |  8 ++++++++
 4 files changed, 42 insertions(+)
 create mode 100644 paillier-service/description.md
 create mode 100644 paillier-service/encrypt.py
 create mode 100644 paillier-service/grader.py
 create mode 100644 paillier-service/problem.yml

diff --git a/paillier-service/description.md b/paillier-service/description.md
new file mode 100644
index 0000000..159bd5b
--- /dev/null
+++ b/paillier-service/description.md
@@ -0,0 +1,3 @@
+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
\ No newline at end of file
diff --git a/paillier-service/encrypt.py b/paillier-service/encrypt.py
new file mode 100644
index 0000000..81c2a9d
--- /dev/null
+++ b/paillier-service/encrypt.py
@@ -0,0 +1,17 @@
+#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)
diff --git a/paillier-service/grader.py b/paillier-service/grader.py
new file mode 100644
index 0000000..eccfd3e
--- /dev/null
+++ b/paillier-service/grader.py
@@ -0,0 +1,14 @@
+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."
diff --git a/paillier-service/problem.yml b/paillier-service/problem.yml
new file mode 100644
index 0000000..f2f440e
--- /dev/null
+++ b/paillier-service/problem.yml
@@ -0,0 +1,8 @@
+title: Paillier Service
+author: neptunia
+hint: https://en.wikipedia.org/wiki/Paillier_cryptosystem
+category: Cryptography
+autogen: false
+programming: false
+value: 400
+  
\ No newline at end of file