https://github.com/azeemba/sour16

Toy version of the sweet32 attack
https://github.com/azeemba/sour16

attack birthday-attack cryptography rot13 toy

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Toy version of the sweet32 attack

• Host: GitHub
• URL: https://github.com/azeemba/sour16
• Owner: azeemba
• Created: 2017-11-24T00:45:03.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2017-11-24T00:47:01.000Z (almost 7 years ago)
• Last Synced: 2024-04-17T03:21:14.840Z (7 months ago)
• Topics: attack, birthday-attack, cryptography, rot13, toy
• Language: Python
• Size: 17.6 KB
• Stars: 13
• Watchers: 3
• Forks: 4
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
sour16

======

This is a toy version of the sweet32 attack: https://sweet32.info/

The attack is an example of a birthday attack which exploits crypto algorithms

with small block sizes in CBC mode. The attack requires generation of a lot of

encrypted blocks with known plaintext. After the generation, identical

encrypted blocks can be identified and used to identify the plaintext value of

the blocks with unknown plaintext.

sour16 uses `rot13` as its base encryption algorithm. Though basically any

hashing/encryption algorithm with customizable block size and chained in CBC

mode would work here.

Similarly to sweet32, sour16 generates a lot of encrypted HTTP packets where

the only unknown is a cookie value. Then uses the attack to retrieve the cookie

value.

## Scripts

### Packet Generation: 

`generate_packets.py`: The script allows you to generate encrypted packets and

dump them to a file. It supports `-N` flag to change number of packets

generated (in the 1000s). It also allows configuration of the cookie value or

the block size.

Example command:

```sh

./generate_packets.py --count 30 --cookie "SECRET COOKIE" --block-size 4 30k-32bit.out

# creates a file called 30k-32bit.out

# creates 30,000 encrypted packets with a 4 bytes (32 bit) block size

# each packet has the cookie set to "SECRET COOKIE"

```

### Retrieving cookie by finding identical blocks

`sour16.py`: This is the script that executes the actual attack and requires a

file that is generated using the `generate_packets.py` script. Since the block

size can vary, the script needs to know the block size used for the encryption

as well.

Example command:

```

./sour16.py --block-size 4 30k-32bit.out

Retrieved the entire cookie! SECRET COOKIE

```

As shown above, the cookie was succesfully retrieved!

## Stats

`find_expected_packet_counts.py` runs many cycles of encrypt-decrypt for

varying block size to figure out how many packets are needed on average. The

numbers below are very course but give a rought idea of packet count as a

function of block size.

|Block size| Block size| Num Packets| File size| Block count|

|---|---|---|---|---|

|2 byte| 16 bits| 40 packets| 28KB| 28k blocks|

|3 byte| 24 bits| 1000 packets| 700KB| 364k blocks|

|4 byte| 32 bits| 12500 packets| 8.4MB| 2.8M blocks|

|5 byte| 40 bits| 250,000 packets| 174MB| 35M blocks|