openssl/doc/man7/EVP_PKEY-X25519.pod
slontis 78c44b0594 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)
2022-09-23 09:24:47 +01:00

121 lines
3.2 KiB
Plaintext

=pod
=head1 NAME
EVP_PKEY-X25519, EVP_PKEY-X448, EVP_PKEY-ED25519, EVP_PKEY-ED448,
EVP_KEYMGMT-X25519, EVP_KEYMGMT-X448, EVP_KEYMGMT-ED25519, EVP_KEYMGMT-ED448
- EVP_PKEY X25519, X448, ED25519 and ED448 keytype and algorithm support
=head1 DESCRIPTION
The B<X25519>, B<X448>, B<ED25519> and B<ED448> keytypes are
implemented in OpenSSL's default and FIPS providers. These implementations
support the associated key, containing the public key I<pub> and the
private key I<priv>.
=head2 Keygen Parameters
=over 4
=item "dhkem-ikm" (B<OSSL_PKEY_PARAM_DHKEM_IKM>) <octet string>
DHKEM requires the generation of a keypair using an input key material (seed).
Use this to specify the key material used for generation of the private 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.
This is only supported by X25519 and X448.
=back
Use EVP_PKEY_CTX_set_params() after calling EVP_PKEY_keygen_init().
=head2 Common X25519, X448, ED25519 and ED448 parameters
In addition to the common parameters that all keytypes should support (see
L<provider-keymgmt(7)/Common parameters>), the implementation of these keytypes
support the following.
=over 4
=item "group" (B<OSSL_PKEY_PARAM_GROUP_NAME>) <UTF8 string>
This is only supported by X25519 and X448. The group name must be "x25519" or
"x448" respectively for those algorithms. This is only present for consistency
with other key exchange algorithms and is typically not needed.
=item "pub" (B<OSSL_PKEY_PARAM_PUB_KEY>) <octet string>
The public key value.
=item "priv" (B<OSSL_PKEY_PARAM_PRIV_KEY>) <octet string>
The private key value.
=item "encoded-pub-key" (B<OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY>) <octet string>
Used for getting and setting the encoding of a public key for the B<X25519> and
B<X448> key types. Public keys are expected be encoded in a format as defined by
RFC7748.
=back
=head2 ED25519 and ED448 parameters
=over 4
=item "mandatory-digest" (B<OSSL_PKEY_PARAM_MANDATORY_DIGEST>) <UTF8 string>
The empty string, signifying that no digest may be specified.
=back
=head1 CONFORMING TO
=over 4
=item RFC 8032
=item RFC 8410
=back
=head1 EXAMPLES
An B<EVP_PKEY> context can be obtained by calling:
EVP_PKEY_CTX *pctx =
EVP_PKEY_CTX_new_from_name(NULL, "X25519", NULL);
EVP_PKEY_CTX *pctx =
EVP_PKEY_CTX_new_from_name(NULL, "X448", NULL);
EVP_PKEY_CTX *pctx =
EVP_PKEY_CTX_new_from_name(NULL, "ED25519", NULL);
EVP_PKEY_CTX *pctx =
EVP_PKEY_CTX_new_from_name(NULL, "ED448", NULL);
An B<X25519> key can be generated like this:
pkey = EVP_PKEY_Q_keygen(NULL, NULL, "X25519");
An B<X448>, B<ED25519>, or B<ED448> key can be generated likewise.
=head1 SEE ALSO
L<EVP_KEYMGMT(3)>, L<EVP_PKEY(3)>, L<provider-keymgmt(7)>,
L<EVP_KEYEXCH-X25519(7)>, L<EVP_KEYEXCH-X448(7)>,
L<EVP_SIGNATURE-ED25519(7)>, L<EVP_SIGNATURE-ED448(7)>
=head1 COPYRIGHT
Copyright 2020-2021 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