DS-DEA

An implementation of the Simplified Data Encryption Standard (S-DES) and Double Simplified Data Encryption Algorithm (DS-DEA).

This implementation includes code to run meet-in-the-middle and brute force attacks on a hardcoded set of plaintext/ciphertext pairs listed in the following section.

Installation and Usage

After cloning the repository, check to ensure you have swift installed on your system with: swift --version. If you do not have version 5.1.4 or greater, instructions to install are here.

Once installed, enter the top-level project directory. Run the code with the following command:

swift run DSDEA test|mitm|brute|decrypt

Attack Tests

The following plaintext/ciphertext pairs listed below correspond to a key pair combination:

0x42/0x52, 0x72/0xf0, 0x75/0xbe, 0x74/0x69, 0x65/0x8a

The keys can be determined using the provided code. See below for expected results.

Found Keys

The keys found for the provided plaintext/ciphertext pairs are:

• Key 1: 0b1100111111
• Key 2: 0b0101010011

or in hexadecimal:

• Key 1: 0x33F
• Key 2: 0x153

Below are the time for one run of each of meet-in-the-middle and brute force attacks:

• MITM: 1.176 seconds
• Brute Force: 3:30.07 minutes

Weak Keys

There are 4 weak keys for S-DES:

0b0000000000
0b1111111111
0b0111101000
0b1000010111

or in hexadecimal:

0x000
0x3FF
0x1E8
0x217

These keys will produce the same round key for all rounds.