=pod

=head1 NAME

CMS_EnvelopedData_create_ex, CMS_EnvelopedData_create,
CMS_AuthEnvelopedData_create, CMS_AuthEnvelopedData_create_ex
- Create CMS envelope

=head1 SYNOPSIS

 #include <openssl/cms.h>

 CMS_ContentInfo *
 CMS_EnvelopedData_create_ex(const EVP_CIPHER *cipher, OSSL_LIB_CTX *libctx,
                             const char *propq);
 CMS_ContentInfo *CMS_EnvelopedData_create(const EVP_CIPHER *cipher);

 CMS_ContentInfo *
 CMS_AuthEnvelopedData_create_ex(const EVP_CIPHER *cipher, OSSL_LIB_CTX *libctx,
                                 const char *propq);
 CMS_ContentInfo *CMS_AuthEnvelopedData_create(const EVP_CIPHER *cipher);

=head1 DESCRIPTION

CMS_EnvelopedData_create_ex() creates a B<CMS_ContentInfo> structure
with a type B<NID_pkcs7_enveloped>. I<cipher> is the symmetric cipher to use.
The library context I<libctx> and the property query I<propq> are used when
retrieving algorithms from providers.

CMS_AuthEnvelopedData_create_ex() creates a B<CMS_ContentInfo>
structure with a type B<NID_id_smime_ct_authEnvelopedData>. B<cipher> is the
symmetric AEAD cipher to use. Currently only AES variants with GCM mode are
supported. The library context I<libctx> and the property query I<propq> are
used when retrieving algorithms from providers.

The algorithm passed in the I<cipher> parameter must support ASN1 encoding of
its parameters.

The recipients can be added later using L<CMS_add1_recipient_cert(3)> or
L<CMS_add0_recipient_key(3)>.

The B<CMS_ContentInfo> structure needs to be finalized using L<CMS_final(3)>
and then freed using L<CMS_ContentInfo_free(3)>.

CMS_EnvelopedData_create() and CMS_AuthEnvelopedData_create() are similar to
CMS_EnvelopedData_create_ex() and CMS_AuthEnvelopedData_create_ex()
but use default values of NULL for
the library context I<libctx> and the property query I<propq>.

=head1 NOTES

Although CMS_EnvelopedData_create_ex(), and CMS_EnvelopedData_create(),
CMS_AuthEnvelopedData_create_ex(), and CMS_AuthEnvelopedData_create() allocate
a new B<CMS_ContentInfo> structure, they are not usually used in applications.
The wrappers L<CMS_encrypt(3)> and L<CMS_decrypt(3)> are often used instead.

=head1 RETURN VALUES

If the allocation fails, CMS_EnvelopedData_create_ex(),
CMS_EnvelopedData_create(), CMS_AuthEnvelopedData_create_ex(), and
CMS_AuthEnvelopedData_create() return NULL and set an error code that can be
obtained by L<ERR_get_error(3)>. Otherwise they return a pointer to the newly
allocated structure.

=head1 SEE ALSO

L<ERR_get_error(3)>, L<CMS_encrypt(3)>, L<CMS_decrypt(3)>, L<CMS_final(3)>

=head1 HISTORY

The CMS_EnvelopedData_create_ex() method was added in OpenSSL 3.0.

=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
