DSA_GET0_PQG(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 DSA_GET0_PQG(3ossl) — okay bestie, let's get into it ✨

So we're looking at DSA_GET0_PQG(3ossl) from the OpenSSL manual, and it's literally the page for getting and setting data in a DSA object. No cap, it's giving "let me peek at my params and keys, and also set them, but make it deprecated." The manual name is DSA_GET0_PQG(3ossl) in case you were wondering — and yes, it's a whole vibe.

💖 NAME 💖

DSA_get0_pqg, DSA_set0_pqg, DSA_get0_key, DSA_set0_key, DSA_get0_p, DSA_get0_q, DSA_get0_g, DSA_get0_pub_key, DSA_get0_priv_key, DSA_clear_flags, DSA_test_flags, DSA_set_flags, DSA_get0_engine — these are literally the routines for getting and setting data in a DSA object. That's the whole thing. Periodt.

✨ SYNOPSIS ✨

First things first, you gotta include the header:

#include <openssl/dsa.h>

But like, heads up bestie — the following functions have been deprecated since OpenSSL 3.0, and they can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7). So they're giving "still here but on thin ice" energy.

Here's the full lineup, exactly as it appears:

void DSA_get0_pqg(const DSA *d,
                  const BIGNUM **p, const BIGNUM **q, const BIGNUM **g);
int DSA_set0_pqg(DSA *d, BIGNUM *p, BIGNUM *q, BIGNUM *g);
void DSA_get0_key(const DSA *d,
                  const BIGNUM **pub_key, const BIGNUM **priv_key);
int DSA_set0_key(DSA *d, BIGNUM *pub_key, BIGNUM *priv_key);
const BIGNUM *DSA_get0_p(const DSA *d);
const BIGNUM *DSA_get0_q(const DSA *d);
const BIGNUM *DSA_get0_g(const DSA *d);
const BIGNUM *DSA_get0_pub_key(const DSA *d);
const BIGNUM *DSA_get0_priv_key(const DSA *d);
void DSA_clear_flags(DSA *d, int flags);
int DSA_test_flags(const DSA *d, int flags);
void DSA_set_flags(DSA *d, int flags);
ENGINE *DSA_get0_engine(DSA *d);

🌈 DESCRIPTION 🌈

Okay so all of the functions on this page are deprecated, and applications should instead use EVP_PKEY_get_bn_param(3). That's the glow-up replacement. But let's still understand what these iconic icons do.

A DSA object contains the parameters p, q, and g. It also contains a public key (pub_key) and optionally a private key (priv_key). Like, that's the whole lineup.

Getting the p, q, g parameters 💅

The p, q, and g parameters can be obtained by calling DSA_get0_pqg(). If the parameters have not yet been set, then *p, *q, and *g will be set to NULL. Otherwise they are set to pointers to their respective values. These point directly to the internal representations of the values, and therefore should not be freed directly. That means don't touch, don't free, don't even look at them wrong — they're owned by the DSA object, bestie.

Setting the p, q, g values 🎀

The p, q, and g values can be set by calling DSA_set0_pqg() and passing the new values for p, q, and g as parameters to the function. Calling this function transfers the memory management of the values to the DSA object, and therefore the values that have been passed in should not be freed directly after this function has been called. The DSA object owns them now. No take-backs.

Getting the public and private key values 🦋

To get the public and private key values, use the DSA_get0_key() function. A pointer to the public key will be stored in *pub_key, and a pointer to the private key will be stored in *priv_key. Either may be NULL if they have not been set yet, although if the private key has been set then the public key must be. The values point to the internal representation of the public key and private key values. This memory should not be freed directly. Same energy as before — do not free.

Setting the public and private key values 🌸

The public and private key values can be set using DSA_set0_key(). The public key must be non-NULL the first time this function is called on a given DSA object. The private key may be NULL. On subsequent calls, either may be NULL, which means the corresponding DSA field is left untouched. As for DSA_set0_pqg(), this function transfers the memory management of the key values to the DSA object, and therefore they should not be freed directly after this function has been called. Yes, this is the third time I'm saying "do not free" — it's important, okay?

Grabbing individual values separately 💜

Any of the values p, q, g, priv_key, and pub_key can also be retrieved separately by the corresponding function DSA_get0_p(), DSA_get0_q(), DSA_get0_g(), DSA_get0_priv_key(), and DSA_get0_pub_key(), respectively. Like, if you just want q without the whole pqg drama, you're covered.

Flags, flags, flags 🚩

DSA_set_flags() sets the flags in the flags parameter on the DSA object. Multiple flags can be passed in one go (bitwise ORed together). Any flags that are already set are left set. It's additive, not destructive — we love that.

DSA_test_flags() tests to see whether the flags passed in the flags parameter are currently set in the DSA object. Multiple flags can be tested in one go. All flags that are currently set are returned, or zero if none of the flags are set. It's giving "tell me what's up."

DSA_clear_flags() clears the specified flags within the DSA object. Bye bye, flags.

Engine handle 🧚

DSA_get0_engine() returns a handle to the ENGINE that has been set for this DSA object, or NULL if no such ENGINE has been set. That's it. That's the function.

💀 NOTES 💀

Okay, this is important so listen up, bestie. Values retrieved with DSA_get0_key() are owned by the DSA object used in the call and may therefore not be passed to DSA_set0_key(). If needed, duplicate the received value using BN_dup() and pass the duplicate. Do not skip the multiply. The same applies to DSA_get0_pqg() and DSA_set0_pqg(). So like, don't try to recycle the same pointer and hope for the best — that's not the move.

🫶 RETURN VALUES 🫶

DSA_set0_pqg() and DSA_set0_key() return 1 on success or 0 on failure. Binary. Iconic.

DSA_test_flags() returns the current state of the flags in the DSA object.

DSA_get0_engine() returns the ENGINE set for the DSA object or NULL if no ENGINE has been set.

👑 SEE ALSO 👑

Go check out these other pages, bestie — they're all linked in spirit:

EVP_PKEY_get_bn_param(3), DSA_new(3), DSA_new(3) — yes, it's listed twice in the original, so I'm listing it twice, no shame — DSA_generate_parameters(3), DSA_generate_key(3), DSA_dup_DH(3), DSA_do_sign(3), DSA_set_method(3), DSA_SIG_new(3), DSA_sign(3), DSA_size(3), DSA_meth_new(3).

🦋 HISTORY 🦋

The functions described here were added in OpenSSL 1.1.0 and deprecated in OpenSSL 3.0. It's giving "we had a good run but now we're deprecated" and honestly? We respect the journey.

Copyright 2016-2018 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. This manual page is from OpenSSL version 3.5.0, dated 2026-09-25 — so like, it's recent but the functions inside are deprecated. The way that works is honestly a little iconic. 💅✨

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