page_des(3)

✨ page_des — DES, the Data Encryption Standard crypto interface ✨

okay bestie, buckle up, we're talking about DES 💖 this is the Heimdal crypto library page for it, and yes it's giving "vintage but problematic." The library functions live over here: DES crypto functions.

DES was created by IBM, then modififed by the NSA (yeah, them 🙈), and then adopted by NBS (which is now NIST) and published as FIPS PUB 46 — later updated by FIPS 46-1.

🚨 MAJOR PSA: since 19th May 2005, DES was withdrawn by NIST and should no longer be used. Like, at all. Periodt. 💀 For replacement encryption algorithms and interfaces, go look at EVP - generic crypto interface instead, fr fr.

Wanna read the whole interesting history of DES? It's honestly iconic drama. Wikipedia's got you: http://www.wikipedia.org/wiki/Data_Encryption_Standard 🦋

🔑 DES key generation 🔑

so to generate a DES key safely, you literally have to use the code-snippet below. why?? because DES_random_key() can fail with an abort() in case of a failure to start the random generator 😭 not the vibe.

There's a replacement function, DES_new_random_key(), BUT — plot twist — that function does not exist in OpenSSL. 🫠

DES_cblock key;
do {
    if (RAND_rand(&key, sizeof(key)) != 1)
         goto failure;
    DES_set_odd_parity(key);
} while (DES_is_weak_key(&key));

📜 DES implementation history 📜

okay story time 🎀 There was no complete BSD licensed, fast, GPL compatible implementation of DES out there, so Love wrote the part that was missing — fast key schedule setup — and adapted the interface to the orignal libdes. slay 💅

The document that got the whole thing started for real was 'Efficient Implementation of the Data Encryption Standard' by Dag Arne Osvik. The PC1 transformation never got to working 🙈 — instead, table-lookup was used for all key schedule setup. That document was super useful because it de-mystified other implementations for me. king behavior honestly 👑

The core DES function (SBOX + P transformation) is from Richard Outerbridge's public domain DES implementation. My sanity is saved thanks to his work. Thank you Richard 🫶

Version 7.8.0 · Tue Nov 15 2022 · Heimdal crypto library · page_des(3) — and that's the whole page bestie, ty for coming to my TED talk, stay encrypted and stay away from DES 💖✨🎀🦋