This is a small command line utility for generating and encrypting messages using the provided 64bit key. This is just a simplified implementation of DES(ECB mode) that I've done in order to satisfy my curiosity on how to implement a crypto cipher top to bottom. The padding strategy we use is PKCS5. We don't use like in openssl a password salt combination and also we don't verify if the imput key or that one we generate is weak or not.
I used as a reference implementing DES the following document.
➜ des master ✗ make
➜ des master ✗ ./main --help
des encryption cipher in ECB mode and using PKCS5.0 padding
des -k des.key [-g] input
--help, -h print out the help message
--decrypt, -d decrypt the input
--generate-key, -g generate random 64bit key
--key, -k input key for enc and dec➜ des master ✗ ./main --generate-key des.key
➜ des master ✗ echo -n "This is just a simple plaintext that we want to encrypt" | ./main --key des.key > encrypted.txt
➜ des master ✗ hexdump -C encrypted.txt
00000000 6e 44 22 a0 ab b0 dd 69 f0 53 20 6c 47 c4 35 d9 |nD"....i.S lG.5.|
00000010 e1 46 9f f8 8d 0c 70 84 30 da 7c 64 d2 fb de 10 |.F....p.0.|d....|
00000020 a3 20 60 31 fd 01 88 d3 cb f6 2d 32 48 50 f0 08 |. `1......-2HP..|
00000030 b9 9b 15 f8 5b 03 6c 59 |....[.lY|
00000038➜ des master ✗ cat encrypted.txt | ./main --key des.key --decrypt > decrypted.txt
➜ des master ✗ hexdump -C decrypted.txt
00000000 54 68 69 73 20 69 73 20 6a 75 73 74 20 61 20 73 |This is just a s|
00000010 69 6d 70 6c 65 20 70 6c 61 69 6e 74 65 78 74 20 |imple plaintext |
00000020 74 68 61 74 20 77 65 20 77 61 6e 74 20 74 6f 20 |that we want to |
00000030 65 6e 63 72 79 70 74 |encrypt|
00000037