openssl/doc/man3/OSSL_SERIALIZER_CTX.pod
Richard Levitte 0d003c52d3 SERIALIZER: New API for serialization of objects through providers
Serialization is needed to be able to take a provider object (such as
the provider side key data) and output it in PEM form, DER form, text
form (for display), and possibly other future forms (XML? JSON? JWK?)

The idea is that a serializer should be able to handle objects it has
intimate knowledge of, as well as object data in OSSL_PARAM form.  The
latter will allow libcrypto to serialize some object with a different
provider than the one holding the data, if exporting of that data is
allowed and there is a serializer that can handle it.

We will provide serializers for the types of objects we know about,
which should be useful together with any other provider that provides
implementations of the same type of object.

Serializers are selected by method name and a couple of additional
properties:

- format        used to tell what format the output should be in.
                Possibilities could include "format=text",
                "format=pem", "format=der", "format=pem-pkcs1"
                (traditional), "format=der-pkcs1" (traditional)
- type          used to tell exactly what type of data should be
                output, for example "type=public" (the public part of
                a key), "type=private" (the private part of a key),
                "type=domainparams" (domain parameters).

This also adds a passphrase callback function type,
OSSL_PASSPHRASE_CALLBACK, which is a bit like OSSL_CALLBACK, but it
takes a few extra arguments to place the result in.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10394)
2019-11-29 20:54:48 +01:00

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=pod
=head1 NAME
OSSL_SERIALIZER_CTX,
OSSL_SERIALIZER_CTX_new,
OSSL_SERIALIZER_CTX_get_serializer,
OSSL_SERIALIZER_settable_ctx_params,
OSSL_SERIALIZER_CTX_set_params,
OSSL_SERIALIZER_CTX_free
- Serializer context routines
=head1 SYNOPSIS
#include <openssl/serializer.h>
typedef struct ossl_serializer_ctx_st OSSL_SERIALIZER_CTX;
OSSL_SERIALIZER_CTX *OSSL_SERIALIZER_CTX_new(OSSL_SERIALIZER *ser);
const OSSL_SERIALIZER *
OSSL_SERIALIZER_CTX_get_serializer(OSSL_SERIALIZER_CTX *ctx);
const OSSL_PARAM *OSSL_SERIALIZER_settable_ctx_params(OSSL_SERIALIZER *ser);
int OSSL_SERIALIZER_CTX_set_params(OSSL_SERIALIZER_CTX *ctx,
const OSSL_PARAM params[]);
void OSSL_SERIALIZER_CTX_free(OSSL_SERIALIZER_CTX *ctx);
=head1 DESCRIPTION
B<OSSL_SERIALIZER_CTX> is a context with which B<OSSL_SERIALIZER>
operations are performed. The context typically holds values, both
internal and supplied by the application, which are useful for the
implementations supplied by providers.
OSSL_SERIALIZER_CTX_new() creates a B<OSSL_SERIALIZER_CTX> associated
with the serializer I<ser>. NULL is a valid I<ser>, the context will
be created anyway, it's just not very useful. This is intentional, to
distinguish between errors in allocating the context or assigning it
values on one hand, and the lack of serializer support on the other.
=begin comment
The above distinction makes it possible for other routines to sense if
they need to report an error or fall back on other methods to
serialize.
=end comment
OSSL_SERIALIZER_CTX_get_serializer() gets the serializer method
currently associated with the context I<ctx>.
OSSL_SERIALIZER_settable_ctx_params() returns an L<OSSL_PARAM(3)>
array of parameter descriptors.
OSSL_SERIALIZER_CTX_set_params() attempts to set parameters specified
with an L<OSSL_PARAM(3)> array I<params>. Parameters that the
implementation doesn't recognise should be ignored.
OSSL_SERIALIZER_CTX_free() frees the given context I<ctx>.
=head1 RETURN VALUES
OSSL_SERIALIZER_CTX_new() returns a pointer to a
B<OSSL_SERIALIZER_CTX>, or NULL if the context structure couldn't be
allocated.
OSSL_SERIALIZER_CTX_get_serializer() returns a pointer to the
serializer method associated with I<ctx>. NULL is a valid return
value and signifies that there is no associated serializer method.
OSSL_SERIALIZER_settable_ctx_params() returns an L<OSSL_PARAM(3)>
array, or NULL if none is available.
OSSL_SERIALIZER_CTX_set_params() returns 1 if all recognised
parameters were valid, or 0 if one of them was invalid or caused some
other failure in the implementation.
=head1 SEE ALSO
L<provider(7)>, L<OSSL_SERIALIZER(3)>
=head1 HISTORY
The functions described here were added in OpenSSL 3.0.
=head1 COPYRIGHT
Copyright 2019 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