[thirdparty/openssl.git] / doc / man3 / OSSL_ENCODER_CTX_new_for_pkey.pod

=pod

=head1 NAME

OSSL_ENCODER_CTX_new_for_pkey,
OSSL_ENCODER_CTX_set_cipher,
OSSL_ENCODER_CTX_set_passphrase,
OSSL_ENCODER_CTX_set_pem_password_cb,
OSSL_ENCODER_CTX_set_passphrase_cb,
OSSL_ENCODER_CTX_set_passphrase_ui
- Encoder routines to encode EVP_PKEYs

=head1 SYNOPSIS

 #include <openssl/encoder.h>

 OSSL_ENCODER_CTX *
 OSSL_ENCODER_CTX_new_for_pkey(const EVP_PKEY *pkey, int selection,
                               const char *output_type,
                               const char *output_structure,
                               const char *propquery);

 int OSSL_ENCODER_CTX_set_cipher(OSSL_ENCODER_CTX *ctx,
                                 const char *cipher_name,
                                 const char *propquery);
 int OSSL_ENCODER_CTX_set_passphrase(OSSL_ENCODER_CTX *ctx,
                                     const unsigned char *kstr,
                                     size_t klen);
 int OSSL_ENCODER_CTX_set_pem_password_cb(OSSL_ENCODER_CTX *ctx,
                                          pem_password_cb *cb, void *cbarg);
 int OSSL_ENCODER_CTX_set_passphrase_ui(OSSL_ENCODER_CTX *ctx,
                                        const UI_METHOD *ui_method,
                                        void *ui_data);
 int OSSL_ENCODER_CTX_set_passphrase_cb(OSSL_ENCODER_CTX *ctx,
                                        OSSL_PASSPHRASE_CALLBACK *cb,
                                        void *cbarg);

=head1 DESCRIPTION

OSSL_ENCODER_CTX_new_for_pkey() is a utility function that creates a
B<OSSL_ENCODER_CTX>, finds all applicable encoder implementations and sets
them up, so almost all the caller has to do next is call functions like
L<OSSL_ENCODER_to_bio(3)>.  I<output_type> determines the final output
encoding, and I<selection> can be used to select what parts of the I<pkey>
should be included in the output.  I<output_type> is further discussed in
L</Output types> below, and I<selection> is further described in
L</Selections>.

Internally, OSSL_ENCODER_CTX_new_for_pkey() uses the names from the
L<EVP_KEYMGMT(3)> implementation associated with I<pkey> to build a list of
applicable encoder implementations that are used to process the I<pkey> into
the encoding named by I<output_type>, with the outermost structure named by
I<output_structure> if that's relevant.  All these implementations are
implicitly fetched, with I<propquery> for finer selection.

If no suitable encoder implementation is found,
OSSL_ENCODER_CTX_new_for_pkey() still creates a B<OSSL_ENCODER_CTX>, but
with no associated encoder (L<OSSL_ENCODER_CTX_get_num_encoders(3)> returns
zero).  This helps the caller to distinguish between an error when creating
the B<OSSL_ENCODER_CTX> and missing encoder implementation, and allows it to
act accordingly.

OSSL_ENCODER_CTX_set_cipher() tells the implementation what cipher
should be used to encrypt encoded keys.  The cipher is given by
name I<cipher_name>.  The interpretation of that I<cipher_name> is
implementation dependent.  The implementation may implement the cipher
directly itself or by other implementations, or it may choose to fetch
it.  If the implementation supports fetching the cipher, then it may
use I<propquery> as properties to be queried for when fetching.
I<cipher_name> may also be NULL, which will result in unencrypted
encoding.

OSSL_ENCODER_CTX_set_passphrase() gives the implementation a
pass phrase to use when encrypting the encoded private key.
Alternatively, a pass phrase callback may be specified with the
following functions.

OSSL_ENCODER_CTX_set_pem_password_cb(), OSSL_ENCODER_CTX_set_passphrase_ui()
and OSSL_ENCODER_CTX_set_passphrase_cb() sets up a callback method that the
implementation can use to prompt for a pass phrase, giving the caller the
choice of preferred pass phrase callback form.  These are called indirectly,
through an internal L<OSSL_PASSPHRASE_CALLBACK(3)> function.

=head2 Output types

The possible B<EVP_PKEY> output types depends on the available
implementations.

OpenSSL has built in implementations for the following output types:

=over 4

=item C<TEXT>

The output is a human readable description of the key.
L<EVP_PKEY_print_private(3)>, L<EVP_PKEY_print_public(3)> and
L<EVP_PKEY_print_params(3)> use this for their output.

=item C<DER>

The output is the DER encoding of the I<selection> of the I<pkey>.

=item C<PEM>

The output is the I<selection> of the I<pkey> in PEM format.

=back

=head2 Selections

I<selection> can be any one of the values described in
L<EVP_PKEY_fromdata(3)/Selections>.

These are only 'hints' since the encoder implementations are free to
determine what makes sense to include in the output, and this may depend on
the desired output.  For example, an EC key in a PKCS#8 structure doesn't
usually include the public key.

=head1 RETURN VALUES

OSSL_ENCODER_CTX_new_for_pkey() returns a pointer to an B<OSSL_ENCODER_CTX>,
or NULL if it couldn't be created.

OSSL_ENCODER_CTX_set_cipher(), OSSL_ENCODER_CTX_set_passphrase(),
OSSL_ENCODER_CTX_set_pem_password_cb(), OSSL_ENCODER_CTX_set_passphrase_ui()
and OSSL_ENCODER_CTX_set_passphrase_cb() all return 1 on success, or 0 on
failure.

=head1 SEE ALSO

L<provider(7)>, L<OSSL_ENCODER(3)>, L<OSSL_ENCODER_CTX(3)>

=head1 HISTORY

The functions described here were added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2019-2022 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
Commit	Line	Data
ece9304c RL	1	=pod
	2
	3	=head1 NAME
	4
fe75766c	5	OSSL_ENCODER_CTX_new_for_pkey,
ece9304c RL	6	OSSL_ENCODER_CTX_set_cipher,
ece9304c RL	7	OSSL_ENCODER_CTX_set_passphrase,
b8975c68	8	OSSL_ENCODER_CTX_set_pem_password_cb,
ece9304c	9	OSSL_ENCODER_CTX_set_passphrase_cb,
b8975c68	10	OSSL_ENCODER_CTX_set_passphrase_ui
ece9304c RL	11	- Encoder routines to encode EVP_PKEYs
	12
	13	=head1 SYNOPSIS
	14
	15	#include <openssl/encoder.h>
	16
b8975c68	17	OSSL_ENCODER_CTX *
fe75766c TM	18	OSSL_ENCODER_CTX_new_for_pkey(const EVP_PKEY *pkey, int selection,
	19	const char *output_type,
	20	const char *output_structure,
	21	const char *propquery);
ece9304c RL	22
	23	int OSSL_ENCODER_CTX_set_cipher(OSSL_ENCODER_CTX *ctx,
	24	const char *cipher_name,
	25	const char *propquery);
	26	int OSSL_ENCODER_CTX_set_passphrase(OSSL_ENCODER_CTX *ctx,
	27	const unsigned char *kstr,
	28	size_t klen);
b8975c68 RL	29	int OSSL_ENCODER_CTX_set_pem_password_cb(OSSL_ENCODER_CTX *ctx,
b8975c68 RL	30	pem_password_cb cb, void cbarg);
ece9304c RL	31	int OSSL_ENCODER_CTX_set_passphrase_ui(OSSL_ENCODER_CTX *ctx,
	32	const UI_METHOD *ui_method,
	33	void *ui_data);
b8975c68 RL	34	int OSSL_ENCODER_CTX_set_passphrase_cb(OSSL_ENCODER_CTX *ctx,
	35	OSSL_PASSPHRASE_CALLBACK *cb,
	36	void *cbarg);
ece9304c RL	37
	38	=head1 DESCRIPTION
	39
fe75766c	40	OSSL_ENCODER_CTX_new_for_pkey() is a utility function that creates a
b8975c68 RL	41	B<OSSL_ENCODER_CTX>, finds all applicable encoder implementations and sets
b8975c68 RL	42	them up, so almost all the caller has to do next is call functions like
140eee2b RL	43	L<OSSL_ENCODER_to_bio(3)>. I<output_type> determines the final output
	44	encoding, and I<selection> can be used to select what parts of the I<pkey>
	45	should be included in the output. I<output_type> is further discussed in
	46	L</Output types> below, and I<selection> is further described in
	47	L</Selections>.
b8975c68	48
fe75766c	49	Internally, OSSL_ENCODER_CTX_new_for_pkey() uses the names from the
b8975c68 RL	50	L<EVP_KEYMGMT(3)> implementation associated with I<pkey> to build a list of
b8975c68 RL	51	applicable encoder implementations that are used to process the I<pkey> into
b9a2afdf RL	52	the encoding named by I<output_type>, with the outermost structure named by
b9a2afdf RL	53	I<output_structure> if that's relevant. All these implementations are
cbcbac64	54	implicitly fetched, with I<propquery> for finer selection.
b8975c68 RL	55
b8975c68 RL	56	If no suitable encoder implementation is found,
fe75766c	57	OSSL_ENCODER_CTX_new_for_pkey() still creates a B<OSSL_ENCODER_CTX>, but
b8975c68 RL	58	with no associated encoder (L<OSSL_ENCODER_CTX_get_num_encoders(3)> returns
	59	zero). This helps the caller to distinguish between an error when creating
	60	the B<OSSL_ENCODER_CTX> and missing encoder implementation, and allows it to
ece9304c RL	61	act accordingly.
	62
	63	OSSL_ENCODER_CTX_set_cipher() tells the implementation what cipher
	64	should be used to encrypt encoded keys. The cipher is given by
	65	name I<cipher_name>. The interpretation of that I<cipher_name> is
b8975c68	66	implementation dependent. The implementation may implement the cipher
ece9304c RL	67	directly itself or by other implementations, or it may choose to fetch
	68	it. If the implementation supports fetching the cipher, then it may
	69	use I<propquery> as properties to be queried for when fetching.
	70	I<cipher_name> may also be NULL, which will result in unencrypted
	71	encoding.
	72
	73	OSSL_ENCODER_CTX_set_passphrase() gives the implementation a
	74	pass phrase to use when encrypting the encoded private key.
	75	Alternatively, a pass phrase callback may be specified with the
	76	following functions.
	77
b8975c68 RL	78	OSSL_ENCODER_CTX_set_pem_password_cb(), OSSL_ENCODER_CTX_set_passphrase_ui()
	79	and OSSL_ENCODER_CTX_set_passphrase_cb() sets up a callback method that the
	80	implementation can use to prompt for a pass phrase, giving the caller the
e304aa87	81	choice of preferred pass phrase callback form. These are called indirectly,
318a9dfa	82	through an internal L<OSSL_PASSPHRASE_CALLBACK(3)> function.
ece9304c	83
140eee2b RL	84	=head2 Output types
	85
	86	The possible B<EVP_PKEY> output types depends on the available
	87	implementations.
	88
	89	OpenSSL has built in implementations for the following output types:
	90
	91	=over 4
	92
	93	=item C<TEXT>
	94
	95	The output is a human readable description of the key.
	96	L<EVP_PKEY_print_private(3)>, L<EVP_PKEY_print_public(3)> and
	97	L<EVP_PKEY_print_params(3)> use this for their output.
	98
	99	=item C<DER>
	100
	101	The output is the DER encoding of the I<selection> of the I<pkey>.
	102
	103	=item C<PEM>
	104
	105	The output is the I<selection> of the I<pkey> in PEM format.
	106
	107	=back
	108
	109	=head2 Selections
	110
00b8706c SL	111	I<selection> can be any one of the values described in
00b8706c SL	112	L<EVP_PKEY_fromdata(3)/Selections>.
140eee2b	113
00b8706c	114	These are only 'hints' since the encoder implementations are free to
140eee2b RL	115	determine what makes sense to include in the output, and this may depend on
	116	the desired output. For example, an EC key in a PKCS#8 structure doesn't
	117	usually include the public key.
	118
ece9304c RL	119	=head1 RETURN VALUES
ece9304c RL	120
fe75766c TM	121	OSSL_ENCODER_CTX_new_for_pkey() returns a pointer to an B<OSSL_ENCODER_CTX>,
fe75766c TM	122	or NULL if it couldn't be created.
ece9304c	123
b8975c68 RL	124	OSSL_ENCODER_CTX_set_cipher(), OSSL_ENCODER_CTX_set_passphrase(),
	125	OSSL_ENCODER_CTX_set_pem_password_cb(), OSSL_ENCODER_CTX_set_passphrase_ui()
	126	and OSSL_ENCODER_CTX_set_passphrase_cb() all return 1 on success, or 0 on
	127	failure.
ece9304c	128
ece9304c RL	129	=head1 SEE ALSO
	130
	131	L<provider(7)>, L<OSSL_ENCODER(3)>, L<OSSL_ENCODER_CTX(3)>
	132
	133	=head1 HISTORY
	134
	135	The functions described here were added in OpenSSL 3.0.
	136
	137	=head1 COPYRIGHT
	138
fecb3aae	139	Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
ece9304c RL	140
	141	Licensed under the Apache License 2.0 (the "License"). You may not use
	142	this file except in compliance with the License. You can obtain a copy
	143	in the file LICENSE in the source distribution or at
	144	L<https://www.openssl.org/source/license.html>.
	145
	146	=cut