SETKEY(3POSIX)

💖 SETKEY(3POSIX) 💖

okay bestie, welcome to the POSIX Programmer's Manual ✨ this one's setkey from section 3POSIX, and she's a whole mood.

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🌸 PROLOG 🌸

heads up, bestie: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux at all. so like… check before you commit, fr fr. 💀

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👑 NAME 👑

setkey — set encoding key (CRYPT) 🎀

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✨ SYNOPSIS ✨

#include <stdlib.h>

void setkey(const char *key);

look at her. simple. iconic. no return value, no drama. 🫶

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🦋 DESCRIPTION 🦋

So setkey() gives you access to an implementation-defined encoding algorithm. iykyk — that means the standard is NOT telling you which algorithm, that's on your implementation. 💅

The argument of setkey() is an array of length 64 bytes containing only the bytes with numerical value of 0 and 1. yes literally just 0s and 1s, she's binary-coded, very demure. 🎀

If this string is divided into groups of 8, the low-order bit in each group is ignored — this gives a 56-bit key which is used by the algorithm. That's THE key, bestie. It's the one that shall be used with the algorithm to encode a string block passed to encrypt(). 🔥

Some technical caveats, and these are important so listen up:

• The setkey() function shall not change the setting of errno if successful.
• An application wishing to check for error situations should set errno to 0 before calling setkey().
• If errno is non-zero on return, an error has occurred.

And the big one: the setkey() function need not be thread-safe. so like… don't be chaotic about it. 😭

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💜 RETURN VALUE 💜

No values are returned. nothing. zero. nada. she's a void function and she's at peace with it. 🧚

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🌈 ERRORS 🌈

The setkey() function shall fail if:

• ENOSYS — The functionality is not supported on this implementation. aka she said "not available in your area" 😭

The following sections are informative.

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🍓 EXAMPLES 🍓

None. (no examples, bestie, the standard said "figure it out" 💀)

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🌸 APPLICATION USAGE 🌸

Decoding need not be implemented in all environments. And here's the tea 🫖 — this is related to government restrictions in some countries on encryption and decryption routines. Historical practice has been to ship a different version of the encryption library without the decryption feature in the routines supplied. Thus the exported version of encrypt() does encoding but not decoding. so the decode side just… wasn't there. not me finding that out 😭

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💅 RATIONALE 💅

None. she has no reasoning to offer. valid. periodt. ✨

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⭐ FUTURE DIRECTIONS ⭐

A future version of the standard may mark this interface as obsolete or remove it altogether. so like… cherish her while you can 🥺

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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 🫶 brought to you by the one and only IEEE/The Open Group, dated 2017 — mwah, slay, go forth and encode 💅✨🎀