Finished up challenges

chals/crypto/easy_rsa/challenge.yml

@@ -16,18 +16,17 @@ description: |-
   TODO: some description
 
   **author**: Sophia
-value: 250
+value: 200
 type: dynamic
 tags: 
   - easy
 extra:
-  initial: 250
+  initial: 200
   decay: 50
   minimum: 50
 flags:
   - sigpwny{rsA_FtW:P}
 files:
   - chal.py
-  - gen.py
 hints:
   - I noticed a [library](https://pycryptodome.readthedocs.io/en/latest/src/public_key/rsa.html) included in the source code...

chals/crypto/easy_rsa/gen.py

@@ -1 +1,26 @@
-#add later
+from Crypto.PublicKey import RSA
+from Crypto.Cipher import PKCS1_v1_5
+import sympy
+
+flags = ["sigpwn","y{rsA_","FtW:P}"]
+
+# Randomly generating two primes
+p = 70979368125456165107
+q = 62874279226076849807
+e = 65539
+n = p*q #4462776610810429874302099425257433084349  
+totn = int(sympy.totient(n))
+d = pow(e,-1,totn) #2524360373456480207131100680183211940587
+
+# Generate public and private keys
+pubkey = RSA.construct((n,e))
+cipher = PKCS1_v1_5.new(pubkey)
+priv = RSA.construct((n,e,d))
+ciph = PKCS1_v1_5.new(priv)
+
+# Prints encryption for each flag chunk
+for flag in flags:
+    ciphertext = cipher.encrypt(flag.encode('utf-8'))
+    print(ciphertext)
+    plaintext = ciph.decrypt(ciphertext, None)
+    print(plaintext.decode("utf-8")) 

chals/crypto/safe-cracking/challenge.yml → chals/crypto/safe_cracking/challenge.yml

@@ -8,12 +8,12 @@ description: |-
   `nc chal.cryptoctf.sigpwny.com 7001`
 
   **author**: Sophia
-value: 150
+value: 200
 type: dynamic
 tags:
   - easy
 extra:
-  initial: 150
+  initial: 200
   decay: 50
   minimum: 50
 flags:

chals/crypto/safe-cracking/server.py → chals/crypto/safe_cracking/server.py

@@ -20,7 +20,7 @@ def print_notes():
     print("The shared key of each problem corresponds to one part of the safe combination.")
     print("1. Anna and Beatrice perform a Diffie-Hellman key exchange where p = 17 and g = 3. Privately, Anna selects 5 and Beatrice chooses 11. What's their shared secret key?")
     print("2. The two perform another key exchange. Now, p = 157 and g = 2. Anna's new private key is 67, while Beatrice's public key is 73. What is Anna's public key?")
-    print("3. Anna forgot her private key and wants to solve for it. However, we know the following:\n\tTheir shared secret key, s, is equal to xx.\n\tThe values of p and g are 67 and 2, respectively.\n\tThe result of Anna's public key is x.\n") #finish later
+    print("3. Anna forgot her private key and wants to solve for it. However, we know the following:\n\tTheir shared secret key, s, is equal to 605790.\n\tThe values of p and g are 3042161 and 5, respectively.\n\tThe result of Beatrice's private key is 73.\n") 
     print("Get ready to start guessing!")
     time.sleep(1)
 
@@ -33,7 +33,8 @@ def main():
         print_notes()
     else:
         print("Might want to view the notes...")
-
+        time.sleep(1)
+        print("Get ready to start guessing!")
     if prompt():
         print("You have unlocked the safe! Please don't take anything except for this flag:", FLAG)
     else:

chals/crypto/safe_cracking/sol.py

@@ -0,0 +1,30 @@
+# PART 1 and PART 2
+# Multiple ways of getting here, can just use an online generator 
+
+# --- PART 3 ---
+# Part 3: Finding A
+
+p = 3042161
+b = 73
+shared_secret = 605790
+
+def find_base(p, b, shared_secret):
+    for base in range(1, p):
+        if pow(base, b, p) == shared_secret:
+            return base
+    return None
+
+# Part 3: Finding a
+base = 5
+A = find_base(p, b, shared_secret)
+
+def find_exponent(p, base, A):
+    for x in range(1, p):
+        if pow(base, x, p) == A:
+            return x
+    return None
+
+a = find_exponent(p, base, A)
+
+print("Third number to unlock safe:", a)
+