Provided by: openssl_3.3.1-2ubuntu2_amd64 bug

NAME
       EVP_KEM-X25519, EVP_KEM-X448 - EVP_KEM X25519 and EVP_KEM X448 keytype and algorithm
       support


DESCRIPTION
       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.

   X25519 and X448 KEM parameters
       "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.


CONFORMING TO
       RFC9180


SEE ALSO
       EVP_PKEY_CTX_set_kem_op(3), EVP_PKEY_encapsulate(3), EVP_PKEY_decapsulate(3)
       EVP_KEYMGMT(3), EVP_PKEY(3), provider-keymgmt(7)


HISTORY
       This functionality was added in OpenSSL 3.2.


COPYRIGHT
       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>.