man > EVP_KEYEXCH-X25519(7)

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📛 NAME

EVP_KEYEXCH-X25519, EVP_KEYEXCH-X448 – X25519 and X448 Key Exchange algorithm support

🚀 Quick Reference

Use Case	Command / API	Description
Generate X25519 key pair	openssl genpkey -algorithm X25519 -out key.pem	Create a private key (includes public key)
Extract public key	openssl pkey -in key.pem -pubout -out pub.pem	Obtain the peer’s public key
Derive shared secret	openssl pkeyutl -derive -inkey key.pem -peerkey peer.pub -out secret.bin	Perform X25519/X448 ECDH
API key generation	EVP_PKEY_keygen(ctx, &pkey) with EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, NID_X25519)	Programmatic key pair creation
API key derivation	EVP_PKEY_derive_init(ctx) → EVP_PKEY_derive(ctx, secret, &secretlen)	Obtain shared secret in code

📖 DESCRIPTION

Key exchange support for the X25519 and X448 key types.

🔑 Key Exchange Parameters

• "pad" (OSSL_EXCHANGE_PARAM_PAD) <unsigned integer>
  See “Common Key Exchange parameters” in provider-keyexch(7).

💡 EXAMPLES

Keys for the host and peer can be generated as shown in “Examples” in EVP_PKEY-X25519(7).

The code to generate a shared secret is identical to “Examples” in EVP_KEYEXCH-DH(7).

🔗 SEE ALSO

EVP_PKEY-FFC(7), EVP_PKEY-DH(7), EVP_PKEY(3), provider-keyexch(7), provider-keymgmt(7), OSSL_PROVIDER-default(7), OSSL_PROVIDER-FIPS(7)

© COPYRIGHT

Copyright 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>.

📛 NAME 🚀 Quick Reference 📖 DESCRIPTION 💡 EXAMPLES 🔗 SEE ALSO © COPYRIGHT