1=pod 2 3=head1 NAME 4 5CMS_encrypt - create a CMS envelopedData structure 6 7=head1 SYNOPSIS 8 9 #include <openssl/cms.h> 10 11 CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in, 12 const EVP_CIPHER *cipher, unsigned int flags); 13 14=head1 DESCRIPTION 15 16CMS_encrypt() creates and returns a CMS 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 certificates carrying RSA, Diffie-Hellman or EC keys are supported by this 23function. 24 25EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use 26because most clients will support it. 27 28The algorithm passed in the B<cipher> parameter must support ASN1 encoding of 29its parameters. 30 31Many browsers implement a "sign and encrypt" option which is simply an S/MIME 32envelopedData containing an S/MIME signed message. This can be readily produced 33by storing the S/MIME signed message in a memory BIO and passing it to 34CMS_encrypt(). 35 36The following flags can be passed in the B<flags> parameter. 37 38If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are 39prepended to the data. 40 41Normally the supplied content is translated into MIME canonical format (as 42required by the S/MIME specifications) if B<CMS_BINARY> is set no translation 43occurs. This option should be used if the supplied data is in binary format 44otherwise the translation will corrupt it. If B<CMS_BINARY> is set then 45B<CMS_TEXT> is ignored. 46 47OpenSSL will by default identify recipient certificates using issuer name 48and serial number. If B<CMS_USE_KEYID> is set it will use the subject key 49identifier value instead. An error occurs if all recipient certificates do not 50have a subject key identifier extension. 51 52If the B<CMS_STREAM> flag is set a partial B<CMS_ContentInfo> structure is 53returned suitable for streaming I/O: no data is read from the BIO B<in>. 54 55If the B<CMS_PARTIAL> flag is set a partial B<CMS_ContentInfo> structure is 56returned to which additional recipients and attributes can be added before 57finalization. 58 59The data being encrypted is included in the CMS_ContentInfo structure, unless 60B<CMS_DETACHED> is set in which case it is omitted. This is rarely used in 61practice and is not supported by SMIME_write_CMS(). 62 63=head1 NOTES 64 65If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is 66B<not> complete and outputting its contents via a function that does not 67properly finalize the B<CMS_ContentInfo> structure will give unpredictable 68results. 69 70Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(), 71PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization 72can be performed by obtaining the streaming ASN1 B<BIO> directly using 73BIO_new_CMS(). 74 75The recipients specified in B<certs> use a CMS KeyTransRecipientInfo info 76structure. KEKRecipientInfo is also supported using the flag B<CMS_PARTIAL> 77and CMS_add0_recipient_key(). 78 79The parameter B<certs> may be NULL if B<CMS_PARTIAL> is set and recipients 80added later using CMS_add1_recipient_cert() or CMS_add0_recipient_key(). 81 82=head1 RETURN VALUES 83 84CMS_encrypt() returns either a CMS_ContentInfo structure or NULL if an error 85occurred. The error can be obtained from ERR_get_error(3). 86 87=head1 SEE ALSO 88 89L<ERR_get_error(3)>, L<CMS_decrypt(3)> 90 91=head1 HISTORY 92 93The B<CMS_STREAM> flag was first supported in OpenSSL 1.0.0. 94 95=head1 COPYRIGHT 96 97Copyright 2008-2018 The OpenSSL Project Authors. All Rights Reserved. 98 99Licensed under the OpenSSL license (the "License"). You may not use 100this file except in compliance with the License. You can obtain a copy 101in the file LICENSE in the source distribution or at 102L<https://www.openssl.org/source/license.html>. 103 104=cut 105