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openssl/doc/man7/EVP_KEM-EC.pod

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Add HPKE DHKEM provider support for EC, X25519 and X448. The code is derived from @sftcd's work in PR #17172. This PR puts the DHKEM algorithms into the provider layer as KEM algorithms for EC and ECX. This PR only implements the DHKEM component of HPKE as specified in RFC 9180. crypto/hpke/hpke_util.c has been added for fuctions that will be shared between DHKEM and HPKE. API's for EVP_PKEY_auth_encapsulate_init() and EVP_PKEY_auth_decapsulate_init() have been added to support authenticated encapsulation. auth_init() functions were chosen rather that a EVP_PKEY_KEM_set_auth() interface to support future algorithms that could possibly need different init functions. Internal code has been refactored, so that it can be shared between the DHKEM and other systems. Since DHKEM operates on low level keys it needs to be able to do low level ECDH and ECXDH calls without converting the keys back into EVP_PKEY/EVP_PKEY_CTX form. See ossl_ecx_compute_key(), ossl_ec_public_from_private() DHKEM requires API's to derive a key using a seed (IKM). This did not sit well inside the DHKEM itself as dispatch functions. This functionality fits better inside the EC and ECX keymanagers keygen, since they are just variations of keygen where the private key is generated in a different manner. This should mainly be used for testing purposes. See ossl_ec_generate_key_dhkem(). It supports this by allowing a settable param to be passed to keygen (See OSSL_PKEY_PARAM_DHKEM_IKM). The keygen calls code within ec and ecx dhkem implementation to handle this. See ossl_ecx_dhkem_derive_private() and ossl_ec_dhkem_derive_private(). These 2 functions are also used by the EC/ECX DHKEM implementations to generate the sender ephemeral keys. Reviewed-by: Hugo Landau <hlandau@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/19068)
2022-08-26 09:54:35 +08:00
=pod
=head1 NAME
EVP_KEM-EC
- EVP_KEM EC keytype and algorithm support
=head1 DESCRIPTION
The B<EC> keytype and its parameters are described in L<EVP_PKEY-EC(7)>.
See L<EVP_PKEY_encapsulate(3)> and L<EVP_PKEY_decapsulate(3)> for more info.
=head2 EC KEM parameters
=over 4
=item "operation" (B<OSSL_KEM_PARAM_OPERATION>)<UTF8 string>
The OpenSSL EC Key Encapsulation Mechanisms only supports the
following operation:
=over 4
=item "DHKEM" (B<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 L<https://www.rfc-editor.org/rfc/rfc9180.html#name-dh-based-kem-dhkem>
=back
This can be set using either EVP_PKEY_CTX_set_kem_op() or
EVP_PKEY_CTX_set_params().
=item "ikme" (B<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.
=back
=head1 CONFORMING TO
=over 4
=item RFC9180
=back
=head1 SEE ALSO
L<EVP_PKEY_CTX_set_kem_op(3)>,
L<EVP_PKEY_encapsulate(3)>,
L<EVP_PKEY_decapsulate(3)>
L<EVP_KEYMGMT(3)>,
L<EVP_PKEY(3)>,
L<provider-keymgmt(7)>
Add HISTORY section to EVP_KEM-EC document. Reviewed-by: Hugo Landau <hlandau@openssl.org> Reviewed-by: Paul Dale <pauli@openssl.org> (Merged from https://github.com/openssl/openssl/pull/19699)
2022-11-17 05:30:14 +08:00
=head1 HISTORY
This functionality was added in OpenSSL 3.2.
Add HPKE DHKEM provider support for EC, X25519 and X448. The code is derived from @sftcd's work in PR #17172. This PR puts the DHKEM algorithms into the provider layer as KEM algorithms for EC and ECX. This PR only implements the DHKEM component of HPKE as specified in RFC 9180. crypto/hpke/hpke_util.c has been added for fuctions that will be shared between DHKEM and HPKE. API's for EVP_PKEY_auth_encapsulate_init() and EVP_PKEY_auth_decapsulate_init() have been added to support authenticated encapsulation. auth_init() functions were chosen rather that a EVP_PKEY_KEM_set_auth() interface to support future algorithms that could possibly need different init functions. Internal code has been refactored, so that it can be shared between the DHKEM and other systems. Since DHKEM operates on low level keys it needs to be able to do low level ECDH and ECXDH calls without converting the keys back into EVP_PKEY/EVP_PKEY_CTX form. See ossl_ecx_compute_key(), ossl_ec_public_from_private() DHKEM requires API's to derive a key using a seed (IKM). This did not sit well inside the DHKEM itself as dispatch functions. This functionality fits better inside the EC and ECX keymanagers keygen, since they are just variations of keygen where the private key is generated in a different manner. This should mainly be used for testing purposes. See ossl_ec_generate_key_dhkem(). It supports this by allowing a settable param to be passed to keygen (See OSSL_PKEY_PARAM_DHKEM_IKM). The keygen calls code within ec and ecx dhkem implementation to handle this. See ossl_ecx_dhkem_derive_private() and ossl_ec_dhkem_derive_private(). These 2 functions are also used by the EC/ECX DHKEM implementations to generate the sender ephemeral keys. Reviewed-by: Hugo Landau <hlandau@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/19068)
2022-08-26 09:54:35 +08:00
=head1 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
L<https://www.openssl.org/source/license.html>.
=cut
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