Comprehensive Tutorial on Simplified Data Encryption Standard (S-DES) by Amit Kumar

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simplified data encryption standard (s-des) algorithm: a comprehensive tutorial with python code

this tutorial delves into the simplified data encryption standard (s-des), a simplified version of the data encryption standard (des) algorithm. while des is a complex block cipher used for robust encryption, s-des is designed for educational purposes, allowing us to understand the fundamental principles of block ciphers without getting bogged down in the intricacies of des.

**understanding s-des:**

s-des is a symmetric-key block cipher. this means that the same key is used for both encryption and decryption. it operates on 8-bit blocks of plaintext and uses a 10-bit key. the encryption and decryption processes involve a series of rounds, each consisting of permutation, substitution, and xor operations.

**key concepts:**

* **symmetric-key cipher:** uses the same key for encryption and decryption.
* **block cipher:** operates on fixed-size blocks of data (in s-des, 8 bits).
* **key generation:** a 10-bit key is transformed into two 8-bit subkeys (k1 and k2) used in different rounds.
* **permutation:** rearranging the order of bits.
* **substitution:** replacing bits based on a predefined lookup table (s-boxes).
* **xor (exclusive or):** a logical operation that outputs 1 if the inputs are different, and 0 if they are the same.

**s-des algorithm overview:**

the s-des algorithm consists of the following steps:

1. **key generation:** generate two subkeys (k1 and k2) from the initial 10-bit key.
2. **initial permutation (ip):** rearrange the bits of the 8-bit plaintext using a predefined permutation table.
3. **round 1:**
* **feistel function (fk):** applies a combination of expansion/permutation, xor with k1, s-box substitution, and permutation.
* **swap:** swaps the left and right halves of the data.
4. **round 2:**
* **feistel function (fk):** applies the same feistel function as in round 1, but xoring with k2 instead of k1.
* **swap (not in this ...

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Simplified Data Encryption Standard
S-DES
Amit Kumar
data encryption
cryptography
symmetric key encryption
block cipher
encryption algorithm
security
data privacy
key generation
plaintext
ciphertext
digital security
information protection