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📛 NAME

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

🚀 Quick Reference

Use Case	Command	Description
🔑 Generate X25519 key pair	openssl genpkey -algorithm X25519 -out priv.pem	Create a private key for X25519 key exchange
🔑 Generate X448 key pair	openssl genpkey -algorithm X448 -out priv.pem	Create a private key for X448 key exchange
🤝 Derive shared secret (X25519)	EVP_PKEY_derive_init() + EVP_PKEY_derive_set_peer() + EVP_PKEY_derive()	Compute shared secret using X25519 keys
🤝 Derive shared secret (X448)	Same API with X448 keys	Compute shared secret using X448 keys
🧩 Set padding parameter	OSSL_EXCHANGE_PARAM_PAD	Control padding of the shared secret output

📖 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.

3.0.2 2026-06-02 EVP_KEYEXCH-X25519(7SSL)

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