NAME

       EVP_KEM-EC - EVP_KEM EC keytype and algorithm support

DESCRIPTION

       The EC keytype and its parameters are described in EVP_PKEY-EC(7).  See
       EVP_PKEY_encapsulate(3) and EVP_PKEY_decapsulate(3) for more info.

   EC KEM parameters
       "operation" (OSSL_KEM_PARAM_OPERATION)<UTF8 string>
           The OpenSSL EC Key Encapsulation Mechanisms only supports the following operation:

           "DHKEM" (OSSL_KEM_PARAM_OPERATION_DHKEM)
               The encapsulate function generates an ephemeral keypair. It produces keymaterial
               by doing an ECDH 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 can only be used for the curves "P-256",
           "P-384" and "P-521" and should have a length of at least the size of the encoded
           private key (i.e. 32, 48 and 66 for the listed curves).  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>.