Add the modules for encryption, decryption.

cryptography_s_des_exploring/sdes/decrypt.py

@@ -0,0 +1,38 @@
+from cryptography_s_des_exploring.sdes.keys import generate_subkeys
+from cryptography_s_des_exploring.sdes.sdes import apply_table, function, IP, s0, expansion, s1, IP_inv
+from cryptography_s_des_exploring.sdes.blocks import decode, decode_bytes
+
+
+def decrypt_block(key: str, block: str):
+    """
+    Encrypt the 8-bit block with 10-bit key.
+
+    key is a binary which represented with a 10 character string.
+    block is a binary which represented with 8 character string.
+    """
+
+    key1, key2 = generate_subkeys(key)
+
+    temp = apply_table(block, IP)
+    temp = function(expansion, s0, s1, key2, temp)
+    temp = temp[4:] + temp[:4]
+    temp = function(expansion, s0, s1, key1, temp)
+    plaintext = apply_table(temp, IP_inv)
+
+    return plaintext
+
+
+def decrypt(key: str, message: str):
+    """
+    Encrypt the message with the 10-bit key.
+    The message is split into 8-bit blocks.
+
+    key is a binary which represented with a 10 character string.
+    """
+
+    decoded = decode_bytes(message)
+
+    decrypted = list(map(lambda b: decrypt_block(key, b), decoded))
+
+    return decode(decrypted)
+

cryptography_s_des_exploring/sdes/encrypt.py

@@ -0,0 +1,38 @@
+from cryptography_s_des_exploring.sdes.keys import generate_subkeys
+from cryptography_s_des_exploring.sdes.sdes import apply_table, function, IP, s0, expansion, s1, IP_inv
+from cryptography_s_des_exploring.sdes.blocks import encode, encode_bytes
+
+
+def encrypt_block(key: str, block: str):
+    """
+    Encrypt the 8-bit block with 10-bit key.
+
+    key is a binary which represented with a 10 character string.
+    block is a binary which represented with 8 character string.
+    """
+
+    key1, key2 = generate_subkeys(key)
+
+    temp = apply_table(block, IP)
+    temp = function(expansion, s0, s1, key1, temp)
+    temp = temp[4:] + temp[:4]
+    temp = function(expansion, s0, s1, key2, temp)
+    ciphertext = apply_table(temp, IP_inv)
+
+    return ciphertext
+
+
+def encrypt(key: str, message: str):
+    """
+    Encrypt the message with the 10-bit key.
+    The message is split into 8-bit blocks.
+
+    key is a binary which represented with a 10 character string.
+    """
+
+    encoded = encode(message)
+
+    encrypted = list(map(lambda b: encrypt_block(key, b), encoded))
+
+    return encode_bytes(encrypted)
+