BN_MOD_INVERSE(3SSL)

📦
version 4.0.3 · 14 versions
, in ubuntu stonking

💖 BN_MOD_INVERSE 💖

okay bestie, we're doing modular inverses today and honestly? it's giving math girlie supremacy. this is the BN_mod_inverse page from the OpenSSL manual (section 3SSL, if you're keeping track 💅).

✨ NAME ✨

BN_mod_inverse — compute inverse modulo n

🌸 SYNOPSIS 🌸

#include <openssl/bn.h>

BIGNUM *BN_mod_inverse(BIGNUM *r, BIGNUM *a, const BIGNUM *n,
                       BN_CTX *ctx);

🦋 DESCRIPTION 🦋

okay so like. BN_mod_inverse() computes the inverse of a modulo n, and it places the result in r — and the whole point is that (a*r)%n==1. that's the vibe check it has to pass, no cap. and if r is NULL? don't even worry, it just creates a brand new BIGNUM for you. iconic behaviour honestly 💅

ctx is a previously allocated BN_CTX and it gets used for temporary variables — think of it as the backstage area where all the messy work happens before the glow-up. also fun fact: r may be the same BIGNUM as a. they can share. we support that 🫶

🎀 NOTES 🎀

⚠️ it is an error to use the same BIGNUM as n. like. do not do that. that's the one thing. not that. 🙈

⭐ RETURN VALUES ⭐

BN_mod_inverse() returns the BIGNUM containing the inverse, and returns NULL on error 😭. if you need the error codes, you can obtain them with ERR_get_error(3) — she'll tell you what went wrong fr fr.

🌈 SEE ALSO 🌈

Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.

okay that's the whole thing, you ate it 💖 this was OpenSSL 4.0.3, dated 2026-09-29, from the BN_MOD_INVERSE(3SSL) manual page — periodt, go forth and invert ✨🧚

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