TLS protocol

Task 1: Diffie–Hellman key exchange

Implementation of this task is in the file dh.py, since the exchange algorithm itself is a part of the Agent class, this file contains only the basic calculations.

Tests are in the file dh_test.py.

Task 2: Diffie–Hellman key

Implemented in helpers.py.

Task 3: Bulk cipher

Implemented in aes.py with custom functions for padding and unpadding, encryption and decryption. Checked with bulk_cipher.py example.

Task 4: Implement simple SSL/TLS setup

Implemented in agent.py, implementation checked with tls_101.py.

Task 5: Man-in-the-middle

Implemented in mitm.py, implementation checked with itls_101.py.

Task 6: RSA

Implemented in rsa.py with tests in rsa_test.py.

Task 7: RSA broadcast attack

Implemented in rsa.py as well, tests also in rsa_test.py. Files test_message and message_captured used in the tests.

The message is Even experts make mistakes. Crypto is extremely difficult to get right.

How Chinese remainder theorem is helping you here?

• this attack is based on the usage of small e and the fact that when an eavesdropper is able to capture at least three cipher texts of the same message m, they are able to "decrypt" it with CRT
• Because we know the remainder of the encrypted m^e modulo three different prime numbers (n1, n2, n3), using the CRT we are able to compute c' = m^e mod n1*n2*n3. Since m^e < n1*n2*n3 we can compute e-th root of m in integers.

Task 8: Bleichenbacher's RSA attack

Not implemented.

Task 9: DSA

Not implemented.

Task 10 (Bonus): DSA domain parameters

Not implemented.