doc/man7/EVP_KEM-EC.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 EVP_KEM-EC
   6 - EVP_KEM EC keytype and algorithm support
   7
   8 =head1 DESCRIPTION
   9
  10 The B<EC> keytype and its parameters are described in L<EVP_PKEY-EC(7)>.
  11 See L<EVP_PKEY_encapsulate(3)> and L<EVP_PKEY_decapsulate(3)> for more info.
  12
  13 =head2 EC KEM parameters
  14
  15 =over 4
  16
  17 =item "operation" (B<OSSL_KEM_PARAM_OPERATION>)<UTF8 string>
  18
  19 The OpenSSL EC Key Encapsulation Mechanisms only supports the
  20 following operation:
  21
  22 =over 4
  23
  24 =item "DHKEM" (B<OSSL_KEM_PARAM_OPERATION_DHKEM>)
  25
  26 The encapsulate function generates an ephemeral keypair. It produces keymaterial
  27 by doing an ECDH key exchange using the ephemeral private key and a supplied
  28 recipient public key. A HKDF operation using the keymaterial and a kem context
  29 then produces a shared secret. The shared secret and the ephemeral public key
  30 are returned.
  31 The decapsulate function uses the recipient private key and the
  32 ephemeral public key to produce the same keymaterial, which can then be used to
  33 produce the same shared secret.
  34 See L<https://www.rfc-editor.org/rfc/rfc9180.html#name-dh-based-kem-dhkem>
  35
  36 =back
  37
  38 This can be set using either EVP_PKEY_CTX_set_kem_op() or
  39 EVP_PKEY_CTX_set_params().
  40
  41 =item "ikme" (B<OSSL_KEM_PARAM_IKME>) <octet string>
  42
  43 Used to specify the key material used for generation of the ephemeral key.
  44 This value should not be reused for other purposes.
  45 It can only be used for the curves "P-256", "P-384" and "P-521" and should
  46 have a length of at least the size of the encoded private key
  47 (i.e. 32, 48 and 66 for the listed curves).
  48 If this value is not set, then a random ikm is used.
  49
  50 =back
  51
  52 =head1 CONFORMING TO
  53
  54 =over 4
  55
  56 =item RFC9180
  57
  58 =back
  59
  60 =head1 SEE ALSO
  61
  62 L<EVP_PKEY_CTX_set_kem_op(3)>,
  63 L<EVP_PKEY_encapsulate(3)>,
  64 L<EVP_PKEY_decapsulate(3)>
  65 L<EVP_KEYMGMT(3)>,
  66 L<EVP_PKEY(3)>,
  67 L<provider-keymgmt(7)>
  68
  69 =head1 HISTORY
  70
  71 This functionality was added in OpenSSL 3.2.
  72
  73 =head1 COPYRIGHT
  74
  75 Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
  76
  77 Licensed under the Apache License 2.0 (the "License").  You may not use
  78 this file except in compliance with the License.  You can obtain a copy
  79 in the file LICENSE in the source distribution or at
  80 L<https://www.openssl.org/source/license.html>.
  81
  82 =cut