RSA

rsa.py

@@ -0,0 +1,19 @@
+from Crypto.PublicKey import RSA
+from Crypto.Cipher import PKCS1_OAEP
+import binascii
+
+keyPair = RSA.generate(1024)
+pubKey = keyPair.public_key()
+print(f"Public Key: (n={hex(pubKey.n)},e={hex(pubKey.e)})")
+pubKeyPEM = pubKey.exportKey()
+print(pubKeyPEM.decode('ascii'))
+
+print(f"Private Key: (n={hex(pubKey.n)},e={hex(keyPair.d)})")
+privKeyPEM = keyPair.exportKey()
+print(privKeyPEM.decode('ascii'))
+
+msg = b"SIES Nerul"
+msg =  msg.encode("utf-8")
+encryptor = PKCS1_OAEP(pubKey)
+encrypted = encryptor.encrypt(msg)
+print("Encrypted: ",binascii.hexlify(encrypted))

rsa2.py

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+import math
+def gcd(a,h):
+    temp = 0
+    while(1):
+        temp = a%h
+        if(temp==0):
+            return h
+        a=h
+        h=temp
+p=3
+q=7
+n=p*q
+e=2
+phi=(p-1)*(q-1)
+
+while (e<phi):
+    if(gcd(e,phi)==1):
+        break
+    else:
+        e+=1
+
+k=2
+d = (1+(k*phi))/e
+msg = 12.0
+print("Message Data = ",msg)
+
+c = pow(msg,e)
+c = math.fmod(c,n)
+print("Encrypted Data = ",c)
+
+m = pow(c,d)
+m = math.fmod(m,n)
+print("Original Message sent = ",m)

rsa3.py

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+import random
+import math
+
+prime = set()
+public_key = None
+private_key = None
+n = None
+
+def primefiller():
+    seive = [True]*250
+    seive[0]=False
+    seive[1]=False
+    for i in range(2,250):
+        for j in range(i*2,250,i):
+            seive[j]=False
+
+    for i in range(len(seive)):
+        if seive[i]:
+            prime.add(i)
+
+def pickrandomprime():
+    global prime
+    k = random.randint(0,len(prime)-1)
+    it=iter(prime)
+    for _ in range(k):
+        next(it)
+
+    ret = next(it)
+    prime.remove(ret)
+    return ret
+
+def setkeys():
+    global public_key,private_key,n
+    prime1 = pickrandomprime()
+    prime2 = pickrandomprime()
+    n = prime1*prime2
+    fi = (prime1-1)*(prime2-1)
+    e=2
+    while True:
+        if math.gcd(e,fi)==1:
+            break
+        e+=1
+    public_key=e
+    d=2
+    while True:
+        if (d*e)%fi==1:
+            break
+        d+=1
+    private_key=d
+
+def encrypt(message):
+    global public_key,n
+    e = public_key
+    encrypted_text=1
+    while e>0:
+        encrypted_text *= message
+        encrypted_text %=n
+        e-=1
+    return encrypted_text
+
+def decrypt(encrypted_text):
+    global private_key,n
+    d = private_key
+    decrypted=1
+    while d>0:
+        decrypted *= encrypted_text
+        decrypted %=n
+        d-=1
+    return decrypted
+
+def encoder(message):
+    encoded = []
+    for letter in message:
+        encoded.append(encrypt(ord(letter)))
+    return encoded
+
+def decoder(encoded):
+    s=''
+    for num in encoded:
+        s+=chr(decrypt(num))
+    return s
+
+if __name__=="__main__":
+    primefiller()
+    setkeys()
+    message = "Shubham"
+    coded = encoder(message)
+    print("Initial Message")
+    print(message)
+    print("The encoded message encrypted by public key:")
+    print(''.join(str(p) for p in coded))
+    print("The decoded message decrypted by public key:")
+    print(''.join(str(p) for p in decoder(coded)))