Add cryptography

ExpandApplication/AsymmetricCiphers.py

@@ -0,0 +1,27 @@
+from fastecdsa import curve, ecdsa, keys
+from fastecdsa.encoding.der import DEREncoder
+
+message = "a message to sign via ECDSA"  # 一些訊息
+
+print("使用預設曲線P256跟雜湊函數SHA2")
+private_key = keys.gen_private_key(curve.P256)
+public_key = keys.get_public_key(private_key, curve.P256)
+print("私密金鑰: " + str(private_key))
+print("公開金鑰: " + str(public_key))
+print(type(public_key))
+
+print("產生數位簽章，為兩個整數r跟s")
+r, s = ecdsa.sign(message, private_key)
+print(r)
+print(s)
+
+print("編碼數位簽章，使用DEREncoder為r跟s做編碼以利傳輸")
+encoded = DEREncoder.encode_signature(r, s)
+b = "數位簽章: "
+for i in encoded:
+    b += str(hex(i)) + " "
+print(b)
+decoded_r, decoded_s = DEREncoder.decode_signature(encoded)
+valid = ecdsa.verify((decoded_r, decoded_s), message, public_key)
+if r == decoded_r and s == decoded_s and valid:
+    print("成功")

ExpandApplication/SymmetricCiphers.py

@@ -0,0 +1,150 @@
+import json
+from base64 import b64encode
+from base64 import b64decode
+from Crypto.Cipher import AES
+from Crypto.Util.Padding import pad
+from Crypto.Util.Padding import unpad
+from Crypto.Random import get_random_bytes
+
+
+class stream_ciphers():
+    def __init__(self, key=None, encrypt_method="aes-256-cfb", iv=None,
+                 segment_size=8, nonce=None, initial_value=None,
+                 counter=None):
+        self.__key = key
+        self.__encrypt_method = encrypt_method
+        self.__iv = iv
+        self.__segment_size = segment_size
+        self.__nonce = nonce
+        self.__initial_value = initial_value
+        self.__counter = counter
+        self.__items = None
+
+    def encrypt(self, message="test"):
+        """aaa."""
+        cipher, iv, segment_size, nonce, initial_value, counter = next(
+            self.encrypt_method)
+        message = message.encode('utf8')
+        if self.__items[2] == "cfb":
+            ct_bytes = cipher.encrypt(pad(message, AES.block_size))
+        else:
+            ct_bytes = cipher.encrypt(message)
+
+        ct_b64 = b64encode(ct_bytes).decode('utf-8')
+
+        result = {
+            'iv': self.__iv,
+            'segment_size': self.__segment_size,
+            'nonce': self.__nonce,
+            'initial_value': self.__initial_value,
+            'counter': self.__counter,
+            'ciphertext': ct_b64,
+        }
+
+        result = json.dumps(result)
+        yield result.encode('utf8')
+
+    def decrypt(self, cipher_message):
+        # We assume that the key was securely shared beforehand
+        try:
+            cipher_message = cipher_message.encode('utf8')
+            b64 = json.loads(cipher_message)
+
+            iv = b64decode(b64['iv'])
+            segment_size = b64decode(b64['segment_size'])
+            nonce = b64decode(b64['nonce'])
+            initial_value = b64decode(b64['initial_value'])
+            counter = b64decode(b64['counter'])
+            ct = b64decode(b64['ciphertext'])
+
+            self.reset_encrypt_method(
+                key=self.__key,
+                encrypt_method=self.__encrypt_method,
+                iv=iv,
+                segment_size=segment_size,
+                nonce=nonce,
+                initial_value=initial_value,
+                counter=counter
+                )
+
+            cipher, iv, segment_size, nonce, initial_value, counter = next(
+                self.encrypt_method)
+
+            if self.__items[2] == "cfb":
+                pt = unpad(cipher.decrypt(ct), AES.block_size)
+            else:
+                pt = cipher.decrypt(ct)
+
+            yield pt
+
+        except:
+            print("Incorrect decryption")
+
+    @property
+    def encrypt_method(self):
+        if self.__key is None:
+            self.__key = get_random_bytes(16)
+        else:
+            self.__key = self.__key
+
+        if len(self.__key) % 8 != 0:
+            raise ValueError('金鑰長度必須是符合8的倍數')
+
+        self.__items = items = self.__encrypt_method.split("-")
+        if items[1] == len(self.__key) * 16:
+            raise ValueError('不符合金鑰設定的位元長度')
+
+        if items[0] == "aes":
+            if items[2] == "ecb":
+                cipher = AES.new(self.__key, AES.MODE_ECB)
+
+            elif items[2] == "cbc":
+                cipher = AES.new(self.__key, AES.MODE_CBC, iv=self.__iv)
+                self.__iv = b64encode(cipher.iv).decode('utf-8')
+
+            elif items[2] == "ctr":
+                cipher = AES.new(self.__key, AES.MODE_CTR, nonce=self.__nonce,
+                                 initial_value=self.__initial_value,
+                                 counter=self.__counter)
+                self.__nonce = b64encode(cipher.nonce).decode('utf-8')
+
+            elif items[2] == "cfb":
+                cipher = AES.new(self.__key, AES.MODE_CFB, iv=self.__iv,
+                                 segment_size=self.__segment_size)
+                self.__iv = b64encode(cipher.iv).decode('utf-8')
+
+            elif items[2] == "ofb":
+                cipher = AES.new(self.__key, AES.MODE_OFB, iv=self.__iv)
+                self.__iv = b64encode(cipher.iv).decode('utf-8')
+
+            elif items[2] == "openpgp":
+                cipher = AES.new(self.__key, AES.MODE_OPENPGP)
+
+            else:
+                raise ValueError('沒有此加密演算法')
+
+        else:
+            raise ValueError('沒有此加密演算法')
+
+        iv = self.__iv
+        segment_size = self.__segment_size
+        nonce = self.__nonce
+        initial_value = self.__initial_value
+        counter = self.__counter
+        yield cipher, iv, segment_size, nonce, initial_value, counter
+
+    def reset_encrypt_method(self, key=None, encrypt_method="aes-256-cfb",
+                             iv=None, segment_size=None, nonce=None,
+                             initial_value=None, counter=None):
+        self.__key = key
+        self.__encrypt_method = encrypt_method
+        self.__iv = iv
+        self.__segment_size = segment_size
+        self.__nonce = nonce
+        self.__initial_value = initial_value
+        self.__counter = counter
+
+
+sc = stream_ciphers()
+print(next(sc.encrypt()))
+print(next(sc.encrypt()))

README.md

@@ -1,3 +1,41 @@
-# Talk
-利用Python撰寫的點對點或中央談話程式。
+Talk
+===
+利用Python撰寫的點對點或中央談話程式，可以選擇使用不同的加密演算法保護傳輸的資料。
 Peer-to-peer or central talk program written in Python.
+
+使用Python3.6，並且使用以下套件:
+- fastecdsa
+- pycryptodome
+- socket
+
+支援的加密演算法:
+- 「對稱性加密演算法」(Symmetric ciphers)
+    - 「串流加密法」(Stream ciphers)
+      - ciphers
+        - ChaCha20
+        - XChaCha20
+        - Salsa20
+      - authentication (MAC)
+        - Poly1305
+    - 「區塊加密法」(Block ciphers)
+      - Ciphers
+        - AES
+      - Classic modes of operation
+        - ECB mode
+        - CBC mode
+        - CTR mode
+        - CFB mode
+        - OFB mode
+        - OpenPGP mode
+      - Modern modes of operation
+        - CCM mode
+        - EAX mode
+        - GCM mode
+        - SIV mode
+        - OCB mode
+
+- 「非對稱性加密演算法」(Asymmetric ciphers):
+  - RSA
+  - ECC
+
+- Hybrid ciphers:結合兩者