added python encryption + rsa encryption

Author: Pl4tt

python/cryptography/rsa_encryption.py

@@ -0,0 +1,63 @@
+# !!! not built for production, only a pseudo random prime generator and low prime numbers
+import sympy
+
+
+A = 50
+
+def generate_key_pair():
+    p = sympy.randprime(A, 4*A)
+    q = sympy.randprime(A, 4*A)
+
+    n = p*q
+    phi = (p-1) * (q-1)
+
+    e = 65537
+
+    d = pow(e, -1, phi)
+    # (e*d)%phi = 1
+
+    public_key = (n, e)
+    private_key = (p, q, d)
+
+    return public_key, private_key
+
+def encrypt(key, raw_text):
+    n = key[0]
+    e = key[1]
+    encrypted_text = ""
+
+    for char in raw_text:
+        intchar = ord(char)
+        encrypted_text += chr(intchar**e % n)
+    
+    return encrypted_text
+
+def decrypt(key, enc_text):
+    n = key[0]*key[1]
+    d = key[2]
+    decrypted_text = ""
+
+    for char in enc_text:
+        intchar = ord(char)
+        decrypted_text += chr(intchar**d % n)
+
+    return decrypted_text
+
+
+
+if __name__ == "__main__":
+    # TEST CASES
+    ka_public, ka_private = generate_key_pair()
+    kb_public, kb_private = generate_key_pair()
+
+    raw_text = "Hello World!"
+    encrypt_msg = encrypt(ka_public, raw_text)
+    decrypt_msg = decrypt(ka_private, encrypt_msg)
+    assert raw_text == decrypt_msg
+    print(raw_text, encrypt_msg, decrypt_msg)
+
+    raw_text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789/*-+.^'"
+    encrypt_msg = encrypt(kb_public, raw_text)
+    decrypt_msg = decrypt(kb_private, encrypt_msg)
+    assert raw_text == decrypt_msg
+    print(raw_text, encrypt_msg, decrypt_msg)