DES - Data Encryption Standard ================================= .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is DES?** DES stands for Data Encryption Standard. It’s a symmetric-key block cipher used to encrypt and decrypt data. DES was one of the earliest encryption standards adopted for securing sensitive information in government and commercial systems. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Why is DES useful?** * DES was a foundational encryption method that helped shape modern cryptography. * It was useful because: * Encrypted data to prevent unauthorized access * Enabled secure communication over untrusted networks * Standardized encryption across industries and governments * Although now considered insecure, DES led to stronger algorithms like AES .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How it works** * Key generation – 56-bit secret key (plus 8 parity bits = 64 bits total) * Encryption – Plaintext is split into 64-bit blocks, encrypted using 16 transformation rounds * Transmission/Storage – Ciphertext is securely sent or stored * Decryption – Same key is used to reverse the encryption process .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Where is DES used?** * Though largely obsolete, DES was used in: * Banking systems – Encrypting ATM PINs and financial data * Smart cards – Early secure authentication methods * Legacy systems – Some still use DES or Triple DES (3DES) * VPNs and secure tunnels – Former use in IPsec and SSL/TLS .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Which OSI layer does this protocol belong to?** * DES operates at the Presentation Layer (Layer 6) * Handles encryption and decryption, affecting how data is formatted for the application * Ensures confidentiality before the data reaches the application layer .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`DES Version&RFC Details ` * :ref:`DES Basic Setup on Ubuntu using IPv4 ` * :ref:`DES Basic Setup on Ubuntu using IPv6 ` * :ref:`DES Protocol Packet Details ` * :ref:`DES Usecases ` * :ref:`DES Basic Features ` * :ref:`DES Feature : Symmetric Key Cipher ` * :ref:`DES Feature : Block Cipher ` * :ref:`DES Feature : Key Size ` * :ref:`DES Feature : Feistel Structure ` * :ref:`DES Feature : Initial & Final Permutations ` * :ref:`DES Feature : Subkeys Generation ` * :ref:`DES Feature : S-Boxes ` * :ref:`DES Feature : Fast in Hardware ` * :ref:`DES Feature : Vulnerable to Brute Force ` * :ref:`DES Feature : Superseded by AES ` * :ref:`Reference links ` .. _DES_step1: .. tab-set:: .. tab-item:: Learnings in this section * In this section, you are going to learn .. _DES_step2: .. tab-set:: .. tab-item:: Terminology * Terminology .. _DES_step3: .. tab-set:: .. tab-item:: Version Info * Version Info .. _DES_step5: .. tab-set:: .. tab-item:: DES Version&RFC Details .. csv-table:: :file: ./DES/des_rfc_details.csv :widths: 10,10,10,30 :header-rows: 1 .. _DES_step20: .. tab-set:: .. tab-item:: DES Basic Setup on Ubuntu using IPv4 * Setup .. _DES_step21: .. tab-set:: .. tab-item:: DES Basic Setup on Ubuntu using IPv6 * Setup .. _DES_step6: .. tab-set:: .. tab-item:: DES Protocol Packet Details **DES Encryption Packet** .. csv-table:: :file: ./DES/des_packet1_details.csv :widths: 10,20,30,10 :header-rows: 1 **DES Decryption Packet** .. csv-table:: :file: ./DES/des_packet2_details.csv :widths: 10,20,30,10 :header-rows: 1 .. _DES_step7: .. tab-set:: .. tab-item:: DES Usecases .. csv-table:: :file: ./DES/des_usecases.csv :widths: 10,20,30 :header-rows: 1 .. _DES_step8: .. tab-set:: .. tab-item:: DES Basic Features .. csv-table:: :file: ./DES/des_features.csv :widths: 10,10,30 :header-rows: 1 .. _DES_step9: .. tab-set:: .. tab-item:: DES Feature : Symmetric Key Cipher **Symmetric Key Cipher - Testcases** .. csv-table:: :file: ./DES/des_feature1_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step10: .. tab-set:: .. tab-item:: DES Feature : Block Cipher **Block Cipher - Testcases** .. csv-table:: :file: ./DES/des_feature2_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step11: .. tab-set:: .. tab-item:: DES Feature : Key Size **Key size - Testcases** .. csv-table:: :file: ./DES/des_feature3_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step12: .. tab-set:: .. tab-item:: DES Feature : Feistel Structure **Feistel Structure - Testcases** .. csv-table:: :file: ./DES/des_feature4_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step13: .. tab-set:: .. tab-item:: DES Feature : Initial & Final Permutations **Initial & Final Permutations - Testcases** .. csv-table:: :file: ./DES/des_feature5_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step14: .. tab-set:: .. tab-item:: DES Feature : Subkeys Generation **Subkeys Generation - Testcases** .. csv-table:: :file: ./DES/des_feature6_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step15: .. tab-set:: .. tab-item:: DES Feature : S-Boxes **S-Boxes - Testcases** .. csv-table:: :file: ./DES/des_feature7_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step16: .. tab-set:: .. tab-item:: DES Feature : Fast in Hardware **Fast in Hardware - Testcases** .. csv-table:: :file: ./DES/des_feature8_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step17: .. tab-set:: .. tab-item:: DES Feature : Vulnerable ro Brute Force **Vulnerable ro Brute Force - Testcases** .. csv-table:: :file: ./DES/des_feature9_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step18: .. tab-set:: .. tab-item:: DES Feature : Superseded by AES **Superseded by AES - Testcases** .. csv-table:: :file: ./DES/des_feature10_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _DES_step19: .. tab-set:: .. tab-item:: Reference links * Reference links