def decrypt_message(ciphertext):
"""Decrypts the ciphertext."""
ciphertext_binary = helper.convert_text_to_binary(ciphertext)
ciphertext_binary = pad_with_zeros(ciphertext_binary)
ciphertext_len = len(ciphertext_binary)
plaintext_binary = []
for i in range(0, ciphertext_len, 64):
block = ciphertext_binary[i:i + 64]
decrypted_block = decrypt_block(block)
plaintext_binary.append(decrypted_block)
plaintext_binary = ''.join(plaintext_binary)
plaintext = helper.convert_binary_to_text(plaintext_binary)
plaintext = remove_padding_chars(plaintext)
return plaintext
def encrypt_message(plaintext):
"""Encrypts the plaintext."""
plaintext_binary = helper.convert_text_to_binary(plaintext)
plaintext_binary = pad_with_zeros(plaintext_binary)
plaintext_len = len(plaintext_binary)
round_keys = get_round_keys()
ciphertext_binary = []
for i in range(0, plaintext_len, 64):
block = plaintext_binary[i:i + 64]
encrypted_block = encrypt_block(block, round_keys)
ciphertext_binary.append(encrypted_block)
ciphertext_binary = ''.join(ciphertext_binary)
ciphertext = helper.convert_binary_to_text(ciphertext_binary)
return ciphertext
def encrypt_message(plaintext):
"""Encrypts the plaintext."""
plaintext_binary = convert_text_to_binary(plaintext)
block_len = int(len(plaintext_binary)//2)
left_portion = plaintext_binary[0:block_len]
right_portion = plaintext_binary[block_len::]
num_rounds = 2
keys = get_keys()
for i in range(num_rounds):
right_portion_len = len(right_portion)
random_key = keys['K{}'.format(i + 1)]
temp = string_xor(right_portion, random_key)
new_left_portion = right_portion
right_portion = string_xor(temp, left_portion)
left_portion = new_left_portion
ciphertext = left_portion + right_portion
return convert_binary_to_text(ciphertext)
def decrypt_message(ciphertext):
"""Decrypts the ciphertext."""
ciphertext_binary = convert_text_to_binary(ciphertext)
block_len = int(len(ciphertext_binary) // 2)
left_portion = ciphertext_binary[0:block_len]
right_portion = ciphertext_binary[block_len::]
num_rounds = 2
keys = get_keys()
num_keys = len(keys)
for i in range(num_rounds):
left_portion_len = len(left_portion)
random_key = keys['K{}'.format(num_keys - i)]
temp = string_xor(left_portion, random_key)
new_right_portion = left_portion
left_portion = string_xor(temp, right_portion)
right_portion = new_right_portion
plaintext = left_portion + right_portion
return convert_binary_to_text(plaintext)
with open('diffie_hellman/keys.json') as f:
keys = json.load(f)
return keys
def decrypt_num(input_num):
"""Decrypts a number."""
keys = get_keys()
sender_public_key = keys['sender_public_key']
private_key = keys['receiver_secret_key']
prime_num = keys['prime_number']
super_key = pow(sender_public_key, private_key, prime_num)
decrypted_num = (input_num - super_key + 2 * prime_num) % prime_num
return decrypted_num
if __name__ == '__main__':
ciphertext = take_input()
encrypted_binary = helper.convert_text_to_binary(ciphertext)
encrypted_num = int(encrypted_binary, 2)
decrypted_num = decrypt_num(encrypted_num)
bit_len = decrypted_num.bit_length()
if bit_len % 8 != 0:
bit_len = (bit_len // 8 + 1) * 8
decrypted_binary = format(decrypted_num, '0{}b'.format(bit_len))
decrypted_message = helper.convert_binary_to_text(decrypted_binary)
print("Decrypted message is {}".format(repr(decrypted_message)))