DiffieHellman

This project partially implements the HTTPS protocol using key exchange through Diffie Hellman and message simmetric encryption through AES.

Python 3.9.0

Useful commands

You can make use of the available Makefile targets to:

Install dependencies

The following command installs all python dependencies on a virtual environment:

$ make install

checking for 'python3'...ok
Collecting antiorm==1.2.1
  Using cached antiorm-1.2.1.tar.gz (171 kB)
Collecting cffi==1.15.0
...
Successfully installed PyYAML-6.0 antiorm-1.2.1 ...

Test the code

The following command tests code behavior using unittest:

$ make test

checking for 'python3'...ok
....
-----------------------------------
Ran 4 tests in 0.050s

OK

Clean the state

The following command cleans the state kept on a SQLite database:

$ make clean

OK

Run the code

This project is able to establish secure communication between two points A and B.

Notice that Diffie Hellman's point of failure is known (man-in-the-middle attack).

To achieve secure communication, first you need to exchange keys between two communication points, and then encrypt/decrypt the messages along the conversation.

Exchange keys

To exchange keys, use mode exch.

First, you need to generate your own secret integer (a), which will be stored, and generate a public hexadecimal (A) to be exchanged with your receiver.

You can also receive a public hexadecimal (B) from your receiver, and generate a key (key), which also will be stored for further communication.

To achieve this goals, first you need to create a argument file (yaml) with a public prime number (p) and its generator (g):

p:  "B10B8F96A080E01DDE92DE5EAE5D54EC52C99FBCFB06A3C\
    69A6A9DCA52D23B616073E28675A23D189838EF1E2EE652C\
    013ECB4AEA906112324975C3CD49B83BFACCBDD7D90C4BD7\
    098488E9C219A73724EFFD6FAE5644738FAA31A4FF55BCCC\
    0A151AF5F0DC8B4BD45BF37DF365C1A65E68CFDA76D4DA70\
    8DF1FB2BC2E4A4371"

g:  "A4D1CBD5C3FD34126765A442EFB99905F8104DD258AC507\
    FD6406CFF14266D31266FEA1E5C41564B777E690F5504F21\
    3160217B4B01B886A5E91547F9E2749F4D7FBD7D3B9A92EE\
    1909D0D2263F80A76A6A24C087A091F531DBF0A0169B6A28\
    AD662A4D18E73AFA32D779D5918D08BC8858F4DCEF97C2A2\
    4855E6EEB22B3B2E5"

Notice: the larger are 'p' and 'g' values, safer is the communication

Generating your puplic and private identifiers

The following command generates your private integer (a) and public hex (A):

$ ./run.sh mode exch --A --argfile args.yaml

A: 3d87e93b6227cf6361bd060b2bc68bff0b285390307a02d1fc02554e65dcac3d727ee62b6cd1b042c311f2960bcc7d7d9cc0d6a05bafbc687f6fcebc72d76cee0b154a1fca0d34154634e83a7e3fd42f5e4e576d3c5f4754ffd0e7a5543cca6c413545e6e95a6a848d58ed971c881e1b2a8887fac09b36b1f7e7b5cb52c6d804

Notice the usage of --argfile <p_g_yaml_file_path> and --A arguments

Generating the communication key

The following command generates the communication key (key), used to encrypt communication messages:

$ ./run.sh mode exch --argfile args.yaml --key 2D3811A7F1AC7A364DAAF2BE4A8F28A12E701FDB0B6E03660617C95A52A46CADCC3B309B928F74ACC2353CA652E26539A095A778FA7FC6A0B3AA76A1665E16DCCAFF58E451B184BA2B4A3CC16D3C2B376B3B6601CD0F98C811EEA3E4362616EA5EA83EA567936DD73B804398E55A08018CD21BE083A4F26490BAF3ED8CB70C13

key: 115eb4313a6f6e1e225b88dc6f630914

Notice the usage of --argfile <p_g_yaml_file_path> and --key arguments

Notice: The value passed for the --key argument must be generated by your receiver (B).

Exchange messages

To exchange messages, use mode talk.

The AES simmetric encrtyption algorithm is used to encrypt and decrypt the messages exchanged.

To achieve the goal of encrypting and decrypting messages you have to execute the steps described at Exchange keys section.

Ecnrypt a message (sender)

The following command encrypts a plaintext message:

$  ./run.sh mode talk --send 'hello world!'

encrypted: 224ac30c8f66c5c7bfc5fa54c30ff4272ee9abb036680c8efe07b4519c21567c

Notice the usage of --send <message> argument

Ecnrypt an inverted message (sender)

The following command encrypts a plaintext inverted message:

$  ./run.sh mode talk --sendinv 'hello world!'

encrypted: 70340ecb967b22a711449be99e9e0d57cda64149c42ae3f0427f593baf3ae9e1

Notice the usage of --sendinv <message> argument

Decrypt a message (receiver)

The following command decrypts an encrypted message using this project:

$ ./run.sh mode talk --recv 224ac30c8f66c5c7bfc5fa54c30ff4272ee9abb036680c8efe07b4519c21567c

decrypted: hello world!

Notice the usage of --recv <message> argument

henriquekops/DiffieHellman