1=pod 2 3=head1 NAME 4 5PKCS7_encrypt - create a PKCS#7 envelopedData structure 6 7=head1 SYNOPSIS 8 9 #include <openssl/pkcs7.h> 10 11 PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, 12 int flags); 13 14=head1 DESCRIPTION 15 16PKCS7_encrypt() creates and returns a PKCS#7 envelopedData structure. B<certs> 17is a list of recipient certificates. B<in> is the content to be encrypted. 18B<cipher> is the symmetric cipher to use. B<flags> is an optional set of flags. 19 20=head1 NOTES 21 22Only RSA keys are supported in PKCS#7 and envelopedData so the recipient 23certificates supplied to this function must all contain RSA public keys, though 24they do not have to be signed using the RSA algorithm. 25 26EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use 27because most clients will support it. 28 29Some old "export grade" clients may only support weak encryption using 40 or 64 30bit RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc() 31respectively. 32 33The algorithm passed in the B<cipher> parameter must support ASN1 encoding of 34its parameters. 35 36Many browsers implement a "sign and encrypt" option which is simply an S/MIME 37envelopedData containing an S/MIME signed message. This can be readily produced 38by storing the S/MIME signed message in a memory BIO and passing it to 39PKCS7_encrypt(). 40 41The following flags can be passed in the B<flags> parameter. 42 43If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are 44prepended to the data. 45 46Normally the supplied content is translated into MIME canonical format (as 47required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation 48occurs. This option should be used if the supplied data is in binary format 49otherwise the translation will corrupt it. If B<PKCS7_BINARY> is set then 50B<PKCS7_TEXT> is ignored. 51 52If the B<PKCS7_STREAM> flag is set a partial B<PKCS7> structure is output 53suitable for streaming I/O: no data is read from the BIO B<in>. 54 55=head1 NOTES 56 57If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not> 58complete and outputting its contents via a function that does not 59properly finalize the B<PKCS7> structure will give unpredictable 60results. 61 62Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(), 63PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization 64can be performed by obtaining the streaming ASN1 B<BIO> directly using 65BIO_new_PKCS7(). 66 67=head1 RETURN VALUES 68 69PKCS7_encrypt() returns either a PKCS7 structure or NULL if an error occurred. 70The error can be obtained from ERR_get_error(3). 71 72=head1 SEE ALSO 73 74L<ERR_get_error(3)>, L<PKCS7_decrypt(3)> 75 76=head1 HISTORY 77 78The B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0. 79 80=head1 COPYRIGHT 81 82Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved. 83 84Licensed under the OpenSSL license (the "License"). You may not use 85this file except in compliance with the License. You can obtain a copy 86in the file LICENSE in the source distribution or at 87L<https://www.openssl.org/source/license.html>. 88 89=cut 90