EVP_PKEY_TODATA(3SSL)

📦
version 4.0.3 · 13 versions
, in ubuntu stonking

✨ EVP_PKEY_TODATA ✨

(that's the 3SSL manual section, bestie — OpenSSL's lil corner of the docs 💅)

okay so picture this: you've got an EVP_PKEY and you're like "girl, what are you actually made of?" — that's literally what these functions are for. they pull the raw key values out as an array of OSSL_PARAM(3) so you can actually look at them. iconic behavior honestly. 🎀

🌸 NAME 🌸

EVP_PKEY_todata, EVP_PKEY_export — functions to return keys as an array of key parameters

🦋 SYNOPSIS 🦋

#include <openssl/evp.h>

int EVP_PKEY_todata(const EVP_PKEY *pkey, int selection, OSSL_PARAM **params);
int EVP_PKEY_export(const EVP_PKEY *pkey, int selection,
                    OSSL_CALLBACK *export_cb, void *export_cbarg);

💖 DESCRIPTION 💖

so the whole vibe of the functions in this page? extracting EVP_PKEY key values as an array of OSSL_PARAM(3). that's it, that's the gig. ✨

  • EVP_PKEY_todata() — pulls the values out of a key pkey, guided by selection. and like, what even is selection? it's described over in "Selections" in EVP_PKEY_fromdata(3), go peek. when you're done with the stuff it hands back, you gotta free the returned parameters in *params using OSSL_PARAM_free(3) or OSSL_PARAM_clear_free(3). no leaks, we don't do that here. 🫶
  • EVP_PKEY_export() — same energy as EVP_PKEY_todata() honestly, but it uses a callback export_cb that gets passed the value of export_cbarg. wanna know more about the callback? it's all in openssl-core.h(7). ⚠️ big important note though: the OSSL_PARAM(3) array that gets passed to the callback is not persistent after the callback returns. meaning once it's gone, it's gone. if you care about any of those items, you have to preserve them yourself — or just use EVP_PKEY_todata() if you need persistence. don't say I didn't warn you. 😭

👑 NOTES 👑

these functions only work with key management methods coming from a provider. no provider, no party. 🙈

they're the mirror function to EVP_PKEY_fromdata(3) — like, one goes in, one comes out. symmetric queen behavior. 💅

also: LMS support is disabled by default at compile-time. to turn it on, specify the enable-lms build configuration option. 🔧

🌈 RETURN VALUES 🌈

  • EVP_PKEY_todata() and EVP_PKEY_export() return 1 for success and 0 for failure.

that's it. binary. slay or flop. ⭐

💜 SEE ALSO 💜

🧚 HISTORY 🧚

  • these functions were added in OpenSSL 3.0.
  • support for ML-DSA, ML-KEM and SLH-DSA was added in OpenSSL 3.5.
  • support for LMS was added in OpenSSL 3.6.

glow-up after glow-up, fr fr. 🔥

Copyright 2021-2026 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 page bestie, you're officially educated 💖 this was OpenSSL 4.0.3, dated 2026-09-29, and it lives in the EVP_PKEY_TODATA(3SSL) manual. go forth and extract those key params, main character. 🌸✨💅

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