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=head1 NAME

CMS_EncryptedData_decrypt, CMS_EnvelopedData_decrypt
- Decrypt CMS EncryptedData or EnvelopedData

=head1 SYNOPSIS

 #include <openssl/cms.h>

 int CMS_EncryptedData_decrypt(CMS_ContentInfo *cms,
                               const unsigned char *key, size_t keylen,
                               BIO *dcont, BIO *out, unsigned int flags);

 BIO *CMS_EnvelopedData_decrypt(CMS_EnvelopedData *env, BIO *detached_data,
                                EVP_PKEY *pkey, X509 *cert,
                                ASN1_OCTET_STRING *secret, unsigned int flags,
                                OSSL_LIB_CTX *libctx, const char *propq);

=head1 DESCRIPTION

CMS_EncryptedData_decrypt() decrypts a I<cms> EncryptedData object using the
symmetric I<key> of size I<keylen> bytes. I<out> is a BIO to write the content
to and I<flags> is an optional set of flags.
I<dcont> is used in the rare case where the encrypted content is detached. It
will normally be set to NULL.

The following flags can be passed in the I<flags> parameter.

If the B<CMS_TEXT> flag is set MIME headers for type C<text/plain> are deleted
from the content. If the content is not of type C<text/plain> then an error is
returned.

CMS_EnvelopedData_decrypt() decrypts, similarly to CMS_decrypt(3),
a CMS EnvelopedData object I<env> using the symmetric key I<secret> if it
is not NULL, otherwise the private key of the recipient I<pkey>.
If I<pkey> is given, it is recommended to provide also the associated
certificate in I<cert> - see L<CMS_decrypt(3)> and the NOTES on I<cert> there.
The optional parameters I<flags> and I<dcont> are used as described above.
The optional parameters library context I<libctx> and property query I<propq>
are used when retrieving algorithms from providers.

=head1 RETURN VALUES

CMS_EncryptedData_decrypt() returns 0 if an error occurred otherwise returns 1.

CMS_EnvelopedData_decrypt() returns NULL if an error occurred,
otherwise a BIO containing the decypted content.

=head1 SEE ALSO

L<ERR_get_error(3)>, L<CMS_EncryptedData_encrypt(3)>, L<CMS_decrypt(3)>

=head1 HISTORY

CMS_EnvelopedData_decrypt() was added in OpenSSL 3.2.

=head1 COPYRIGHT

Copyright 2020 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>.

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