SLAA547C July   2013  – July 2021 MSP430FR5739

 

  1. 1Software Benchmarks
    1. 1.1 AES Benchmarks
    2. 1.2 DES Benchmarks
    3. 1.3 SHA-2 Benchmarks
  2. 2Using Library Functions
    1. 2.1 AES 128
      1. 2.1.1 Encrypting With AES 128
      2. 2.1.2 Decrypting With AES 128
    2. 2.2 DES
      1. 2.2.1 Setting the Key Schedule for DES
      2. 2.2.2 Encrypting and Decryption With DES
      3. 2.2.3 Encryption and Decryption With DES CBC Mode
    3. 2.3 3DES
      1. 2.3.1 Encrypting and Decrypting With Triple DES
    4. 2.4 SHA-2
      1. 2.4.1 Hashing With SHA-256
      2. 2.4.2 Hashing With SHA-224
  3. 3Overview of Library Functions
    1. 3.1 AES 128
      1.      aes_enc_dec
      2.      aes_encrypt
    2. 3.2 DES and 3DES
      1.      Des_Key
      2.      Des_Enc
      3.      Des_Dec
      4.      DES_ENC_CBC
      5.      DES_DEC_CBC
      6.      TripleDES_ENC
      7.      TripleDES_DEC
      8.      TripleDES_ENC_CBC
      9.      TripleDES_DEC_CBC
    3. 3.3 SHA-256 and SHA-224
      1.      SHA_256
  4. 4Cryptographic Standard Definitions
    1. 4.1 AES
      1. 4.1.1 Basic Concept of Algorithm
      2. 4.1.2 Structure of Key and Input Data
      3. 4.1.3 Substitute Bytes (Subbytes Operation)
      4. 4.1.4 Shift Rows (Shiftrows Operation)
      5. 4.1.5 Mix Columns (Mixcolumns Operation)
      6. 4.1.6 Add Round Key (Addroundkey Operation)
      7. 4.1.7 Key Expansion (Keyexpansion Operation)
    2. 4.2 DES and 3DES
      1. 4.2.1 DES Algorithm Structure
      2. 4.2.2 The Function Block
      3. 4.2.3 Key Schedule
      4. 4.2.4 Triple DES
      5. 4.2.5 Cipher Block Chaining (CBC) Mode
    3. 4.3 SHA-256 and SHA-224
      1. 4.3.1 Message Padding and Parsing
      2. 4.3.2 SHA-256 Algorithm
      3. 4.3.3 Equations Found in SHA-256 Algorithm
      4. 4.3.4 SHA-224
  5. 5References
    1.     Revision History

4.2 DES and 3DES

The Data Encryption Standard (DES) was developed in the 1970s by IBM and adopted as a standard by NIST by 1976. The DES algorithm itself has since then been declared insecure by NIST; however, it is believed to be reasonably secure in the form of Triple DES.

The DES algorithm consists of 16 rounds of data manipulation preceded by an initial permutation and followed by the inverse of the initial permutation. Figure 4-9 has a visual description of the algorithm structure. After the initial permutation, the data block is split in half into left and right blocks. The right block is sent through a function block with a round key and then is used as the left block for the next round. The left block is XORed with the result of the function block, the result of which is used as the right block in the next round. This is continued until the last round where the left and right blocks do not switch sides. At this point, the data is put through the inverse of the initial permutation resulting in the wanted cipher text.