=pod

=head1 NAME

PKCS7_decrypt - decrypt content from a PKCS#7 envelopedData structure

=head1 SYNOPSIS

 #include <openssl/pkcs7.h>

 int PKCS7_decrypt(PKCS7 *p7, EVP_PKEY *pkey, X509 *cert, BIO *data, int flags);

=head1 DESCRIPTION

PKCS7_decrypt() extracts and decrypts the content from a PKCS#7 envelopedData
structure. B<pkey> is the private key of the recipient, B<cert> is the
recipients certificate, B<data> is a BIO to write the content to and
B<flags> is an optional set of flags.

=head1 NOTES

OpenSSL_add_all_algorithms() (or equivalent) should be called before using this
function or errors about unknown algorithms will occur.

Although the recipients certificate is not needed to decrypt the data it is needed
to locate the appropriate (of possible several) recipients in the PKCS#7 structure.

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

If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are deleted
from the content. If the content is not of type B<text/plain> then an error is
returned.

=head1 RETURN VALUES

PKCS7_decrypt() returns either 1 for success or 0 for failure.
The error can be obtained from ERR_get_error(3)

=head1 BUGS

PKCS7_decrypt() must be passed the correct recipient key and certificate. It would
be better if it could look up the correct key and certificate from a database.

The lack of single pass processing and need to hold all data in memory as
mentioned in PKCS7_sign() also applies to PKCS7_verify().

=head1 SEE ALSO

L<ERR_get_error(3)>, L<PKCS7_encrypt(3)>

=cut
