SETKEY(3P)

🌸 SETKEY(3P) — POSIX Programmer's Manual 🌸

okay bestie, welcome to the POSIX Programmer's Manual, this is the SETKEY(3P) page and it's giving niche but powerful, iykyk 💅

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✨ PROLOG ✨

Real talk first, no cap: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux at all. Yeah, it might just not exist there. 💀

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🎀 NAME 🎀

setkey — set encoding key (CRYPT). That's the whole vibe, that's the assignment.

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🦋 SYNOPSIS 🦋

#include <stdlib.h>

void setkey(const char *key);

short. sweet. iconic.

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💖 DESCRIPTION 💖

So the setkey() function provides access to an implementation-defined encoding algorithm. Key word: implementation-defined, meaning it's whatever the implementation says it is, not something this page is going to define for you. 🫶

The argument of setkey() is an array of length 64 bytes containing only the bytes with numerical value of 0 and 1. Like, literally just zeros and ones in there, that's the rule, don't come with anything else. If this string is divided into groups of 8, the low-order bit in each group is ignored 🙈 — which gives you a 56-bit key that the algorithm actually uses. That's the key that shall be used with the algorithm to encode a string block passed to encrypt().

The setkey() function shall not change the setting of errno if successful. So if you're an application wishing to check for error situations, bestie, you should set errno to 0 before calling setkey(). Then if errno is non-zero on return, an error has occurred. Simple as that, that's the vibe check. ✅

Also — and this is important — the setkey() function need not be thread-safe. So like, don't just be yeeting it across threads and expecting everything to slay. 😭

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🌈 RETURN VALUE 🌈

No values are returned. Nothing. Void. It's giving silent but doing the work. 💅

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⭐ ERRORS ⭐

The setkey() function shall fail if:

• ENOSYS — The functionality is not supported on this implementation. literally it's just not here, sorry babe 😔

The following sections are informative. (i.e. the rest is tea, not law ☕)

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🍓 EXAMPLES 🍓

None. Nada. Zero. The examples section said "not me having nothing to show" 💀

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🧚 APPLICATION USAGE 🧚

Decoding need not be implemented in all environments. And why, you ask? It's related to government restrictions in some countries on encryption and decryption routines. 🌍 Big geopolitical energy for a little C function, I know.

Historical practice has been to ship a different version of the encryption library without the decryption feature in the routines supplied. So the exported version of encrypt() does encoding but not decoding. That's just how it's been done, periodt.

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🔥 RATIONALE 🔥

None. The rationale section is empty, it said "I have no notes" 💅

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👑 FUTURE DIRECTIONS 👑

A future version of the standard may mark this interface as obsolete or remove it altogether. So like... enjoy it while it lasts bestie, this one's on the chopping block potentially. 😭

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💜 SEE ALSO 💜

• crypt()
• encrypt()
• The Base Definitions volume of POSIX.1‐2017, <stdlib.h>

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🌸 COPYRIGHT 🌸

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page, bestie 💖 this one came to you from IEEE/The Open Group, 2017 — the SETKEY(3P) era, and honestly? iconic. stay encoded, stay safe, mwah 🫶✨