EVP_PKEY-X25519(7ossl)

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version 15.1 · 3 versions
, in freebsd 15.1

💅 EVP_PKEY-X25519 — the 7ossl manual, but make it make sense

okay so real talk, bestie — this whole page is about the OpenSSL manual EVP_PKEY-X25519(7ossl), and it covers a whole friend group of keytypes, not just the one in the title. We're talking:

  • EVP_PKEY-X25519
  • EVP_PKEY-X448
  • EVP_PKEY-ED25519
  • EVP_PKEY-ED448
  • EVP_KEYMGMT-X25519
  • EVP_KEYMGMT-X448
  • EVP_KEYMGMT-ED25519
  • EVP_KEYMGMT-ED448

and it's all about EVP_PKEY X25519, X448, ED25519 and ED448 keytype and algorithm support. iykyk ✨

🌸 NAME 🌸

So the full cast list is EVP_PKEY-X25519, EVP_PKEY-X448, EVP_PKEY-ED25519, EVP_PKEY-ED448, EVP_KEYMGMT-X25519, EVP_KEYMGMT-X448, EVP_KEYMGMT-ED25519 and EVP_KEYMGMT-ED448 — and their whole thing is EVP_PKEY X25519, X448, ED25519 and ED448 keytype and algorithm support. iconic lineup fr fr 👑

✨ DESCRIPTION ✨

okay so the X25519, X448, ED25519 and ED448 keytypes are implemented in OpenSSL's default and FIPS providers. Both of those implementations support the associated key, and that key contains the public key pub and the private key priv. that's the whole vibe 💖

🔑 Keygen Parameters

  • "dhkem-ikm" (OSSL_PKEY_PARAM_DHKEM_IKM) <octet string> — DHKEM needs you to generate a keypair using an input key material (a seed, basically). Use this to specify the key material used for generation of the private key. ⚠️ this value should not be reused for other purposes — one and done, bestie. It should have a length of at least 32 for X25519, and 56 for X448. This is only supported by X25519 and X448.
  • "fips-indicator" (OSSL_PKEY_PARAM_FIPS_APPROVED_INDICATOR) <integer> — this getter is only supported by X25519 and X448 for the FIPS provider. and here's the tea: since X25519 and X448 are unapproved in FIPS 140-3, this getter returns 0. 💀 no cap.

See "Common Information Parameters" in provider-keymgmt(7) for further information.

🫶 friendly reminder: use EVP_PKEY_CTX_set_params() after calling EVP_PKEY_keygen_init().

🦋 Common X25519, X448, ED25519 and ED448 parameters

On top of the common parameters that all keytypes should support (peep "Common parameters" in provider-keymgmt(7)), the implementation of these keytypes also supports the following. slay 🌈

  • "group" (OSSL_PKEY_PARAM_GROUP_NAME) <UTF8 string> — this one is only supported by X25519 and X448. The group name must be "x25519" or "x448" respectively for those algorithms. ngl it's only present for consistency with other key exchange algorithms and is typically not needed. lowkey just vibes ✌️
  • "pub" (OSSL_PKEY_PARAM_PUB_KEY) <octet string> — the public key value. that's it, that's the tweet 💅
  • "priv" (OSSL_PKEY_PARAM_PRIV_KEY) <octet string> — the private key value. keep it secret, keep it safe 🙈
  • "encoded-pub-key" (OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY) <octet string> — used for getting and setting the encoding of a public key for the X25519 and X448 key types. Public keys are expected be encoded in a format as defined by RFC7748. ⭐

🎀 ED25519 and ED448 parameters

  • "mandatory-digest" (OSSL_PKEY_PARAM_MANDATORY_DIGEST) <UTF8 string> — the empty string, signifying that no digest may be specified. literally the empty string, do not come with a digest, it's giving "no thoughts head empty" 🧚

👑 CONFORMING TO 👑

certified standards-compliant behavior, we love to see it 💜

🔥 EXAMPLES 🔥

You can get an EVP_PKEY context by calling:

EVP_PKEY_CTX *pctx =
    EVP_PKEY_CTX_new_from_name(NULL, "X25519", NULL);

EVP_PKEY_CTX *pctx =
    EVP_PKEY_CTX_new_from_name(NULL, "X448", NULL);

EVP_PKEY_CTX *pctx =
    EVP_PKEY_CTX_new_from_name(NULL, "ED25519", NULL);

EVP_PKEY_CTX *pctx =
    EVP_PKEY_CTX_new_from_name(NULL, "ED448", NULL);

and an X25519 key can be generated like this:

pkey = EVP_PKEY_Q_keygen(NULL, NULL, "X25519");

an X448, ED25519, or ED448 key can be generated likewise. same energy, different string 🦋✨

💖 SEE ALSO 💖

go read those, bestie, they're literally the supporting cast 🫶

Copyright 2020-2024 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>.

aaaand that's the whole page, mwah 💋 this was version 3.5.6, dated 2026-04-07, signing off from EVP_PKEY-X25519(7ossl) — go forth and generate keys, main character energy only 🌟🎀

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