DSA_DUP_DH(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 DSA_DUP_DH (3ossl) 💅

okay so bestie, this is a page from the 3ossl manual family, and ngl it's a little bit of a vintage moment — we're talking about turning a DSA thing into a DH thing. Let's get into it 🎀

✨ NAME ✨

DSA_dup_DH — create a DH structure out of DSA structure. that's literally the whole vibe. 🦋

🌸 SYNOPSIS 🌸

#include <openssl/dsa.h>

so before you even think about calling this, heads up 👑 — the following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

DH *DSA_dup_DH(const DSA *r);

like. she's deprecated, bestie. she's still here, but she's on the way out 😭

💖 DESCRIPTION 💖

The function described on this page is deprecated. and not in a cute retro way — there is no direct replacement, so applications should use the EVP_PKEY APIs for Diffie-Hellman operations. periodt. that's the migration path, no cap. ✨

DSA_dup_DH() duplicates DSA parameters/keys as DH parameters/keys. it's giving copy-paste but make it cryptography 💅

but here's the tea ☕ — q is lost during that conversion, but the resulting DH parameters contain its length. so q itself? gone. the length of q? she's still in the building. iykyk 🫶

🔥 RETURN VALUES 🔥

DSA_dup_DH() returns the new DH structure, and NULL on error. and if you get that NULL, don't panic — the error codes can be obtained by ERR_get_error(3). go read the receipts, bestie 💀

⭐ NOTE ⭐

Be careful to avoid small subgroup attacks when using this. 🚨

like fr fr, this is not a drill — small subgroup attacks are real and you do NOT want that energy in your crypto. protect yourself. 🛡️💜

🌈 SEE ALSO 🌈

go read those, they're all linked in the group chat 💖

🧚 HISTORY 🧚

This function was deprecated in OpenSSL 3.0. so yeah, she's been on the deprecated list for a minute 🌸

Copyright 2000-2020 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>.

and that's the whole page, bestie!! 🎀 written by the OpenSSL girlies, version 3.5.0, dated 2026-09-25 — mwah, slay, go forth and use EVP_PKEY instead 💅✨🦋

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