EVP_KEM-X25519, EVP_KEM-X448 - EVP_KEM X25519 and EVP_KEM X448
keytype and algorithm support
The X25519 and <X448> keytype and its parameters are
described in EVP_PKEY-X25519(7). See EVP_PKEY_encapsulate(3)
and EVP_PKEY_decapsulate(3) for more info.
- "operation" (OSSL_KEM_PARAM_OPERATION)<UTF8
string>
- The OpenSSL X25519 and X448 Key Encapsulation Mechanisms only support the
following operation:
- "DHKEM" (OSSL_KEM_PARAM_OPERATION_DHKEM)
- The encapsulate function generates an ephemeral keypair. It produces
keymaterial by doing an X25519 or X448 key exchange using the ephemeral
private key and a supplied recipient public key. A HKDF operation using
the keymaterial and a kem context then produces a shared secret. The
shared secret and the ephemeral public key are returned. The decapsulate
function uses the recipient private key and the ephemeral public key to
produce the same keymaterial, which can then be used to produce the same
shared secret. See
<https://www.rfc-editor.org/rfc/rfc9180.html#name-dh-based-kem-dhkem>
This can be set using either EVP_PKEY_CTX_set_kem_op() or
EVP_PKEY_CTX_set_params().
- "ikme" (OSSL_KEM_PARAM_IKME) <octet string>
- Used to specify the key material used for generation of the ephemeral key.
This value should not be reused for other purposes. It should have a
length of at least 32 for X25519, and 56 for X448. If this value is not
set, then a random ikm is used.
EVP_PKEY_CTX_set_kem_op(3), EVP_PKEY_encapsulate(3),
EVP_PKEY_decapsulate(3) EVP_KEYMGMT(3), EVP_PKEY(3),
provider-keymgmt(7)
This functionality was added in OpenSSL 3.2.
Copyright 2022 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>.