tomato-testing/docs/updates/Crypto.md
Green Sky b2ae9530a4 Squashed 'external/toxcore/c-toxcore/' changes from e29e185c03..f1df709b87
f1df709b87 feat: add ngc events
1b6c907235 refactor: Make event dispatch ordered by receive time.
b7f9367f6f test: Upgrade cppcheck, fix some warnings.
766e62bc89 chore: Use `pkg_search_module` directly in cmake.
00ff078f91 cleanup: Use target_link_libraries directly in cmake.
c58928cc89 chore: Add `IMPORTED_TARGET` to pkg-config packages.
895a6af122 cleanup: Remove NaCl support.
41dfb1c1c0 fix: unpack enum function names in event impl generator
447666d1a1 chore: Disable targets for cross-compilation.
572924e924 chore: Build a docker image with coverage info in it.
415cb78f5e cleanup: Some portability/warning fixes for Windows builds.
425216d9ec fix: Correct a use-after-free and fix some memory leaks.
4b1cfa3e08 refactor: Change all enum-like `#define` sequences into enums.
d3c2704fa9 chore: Fix make_single_file to support core-only.
0ce46b644e refactor: Change the `TCP_PACKET_*` defines into an enum.
22cd38ad50 adopt event impl generation tool to #2392
f31ea1088a add the event impl generation tool
4e603bb613 refactor: Use `enum-from-int` rule from tokstyle.
19d8f180d6 chore: Update github actions `uses`.
6a895be0c7 test: Make esp32 build actually try to instantiate tox.
65d09c9bfb cleanup: Remove test net support.
REVERT: e29e185c03 feat: add ngc events

git-subtree-dir: external/toxcore/c-toxcore
git-subtree-split: f1df709b8792da4c0e946d826b11df77d565064d
2023-12-27 12:37:22 +01:00

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Markdown

Encryption library used: https://doc.libsodium.org/
When running the program for the first time the crypto_box_keypair() function is used to
generate the users public-private key pair. (32 bytes each)
The generated public key is set as the client_id of the peer.
Adding a friend
---------------
Alice adds Bob to her friend list by adding his 32 byte public key (client_id) to her friend list.
2 cases:
case 1: Alice adds the public key of Bob, then Bob waits for Alice to attempt to connect to him.
case 2: Bob and Alice add their respective public keys to their friend lists at the same time.
case 1:
Alice sends an onion data (see: Prevent_tracking.txt) packet to Bob with the encrypted part containing the friend request like so:
```
[char with a value of 32][nospam number (4 bytes)][Message]
```
Ex message: hello Bob it's me Alice -_- add me pl0x.
For more info on the nospam see: Spam_Prevention.txt
Bob receives the request and decrypts the message using the function crypto_box_open()
If the message decrypts successfully:
If Alice is already in Bob's friend list: case 2
If Alice is not in Bob's friend list and the nospam is good: Bob is prompt to add Alice and is shown the message from her.
If Bob accepts Alice friend request he adds her public key to his friend list.
case 2:
Bob and Alice both have the others public key in their friend list, they are ready for the next step: Connecting to an already added friend
In the next step only crypto_box() is used for encryption and only crypto_box_open() for decryption (just like in the last step.)
Connecting to an already added friend
-------------------------------------
see: Tox_middle_level_network_protocol.txt
Crypto request packets
--------------------------------------
```
[char with a value of 32][Bob (The receiver's) Public key (client_id) (32 bytes))][Alice's (The sender's) Public key (client_id) (32 bytes)][Random nonce (24 bytes)][Encrypted message]
```
The encrypted message is encrypted with crypto_box() (using Bob's public key, Alice's private key and the nonce (randomly generated 24 bytes)) and is a message from Alice in which she tells Bob who she is.
Each node can route the request to the receiver if they are connected to him. This is to bypass bad NATs.