5 CMS_encrypt - create a CMS envelopedData structure
9 #include <openssl/cms.h>
11 CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in,
12 const EVP_CIPHER *cipher, unsigned int flags);
16 CMS_encrypt() creates and returns a CMS EnvelopedData structure. B<certs>
17 is a list of recipient certificates. B<in> is the content to be encrypted.
18 B<cipher> is the symmetric cipher to use. B<flags> is an optional set of flags.
20 Only certificates carrying RSA, Diffie-Hellman or EC keys are supported by this
23 EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use
24 because most clients will support it.
26 The algorithm passed in the B<cipher> parameter must support ASN1 encoding of
29 Many browsers implement a "sign and encrypt" option which is simply an S/MIME
30 envelopedData containing an S/MIME signed message. This can be readily produced
31 by storing the S/MIME signed message in a memory BIO and passing it to
34 The following flags can be passed in the B<flags> parameter.
36 If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are
37 prepended to the data.
39 Normally the supplied content is translated into MIME canonical format (as
40 required by the S/MIME specifications) if B<CMS_BINARY> is set no translation
41 occurs. This option should be used if the supplied data is in binary format
42 otherwise the translation will corrupt it. If B<CMS_BINARY> is set then
43 B<CMS_TEXT> is ignored.
45 OpenSSL will by default identify recipient certificates using issuer name
46 and serial number. If B<CMS_USE_KEYID> is set it will use the subject key
47 identifier value instead. An error occurs if all recipient certificates do not
48 have a subject key identifier extension.
50 If the B<CMS_STREAM> flag is set a partial B<CMS_ContentInfo> structure is
51 returned suitable for streaming I/O: no data is read from the BIO B<in>.
53 If the B<CMS_PARTIAL> flag is set a partial B<CMS_ContentInfo> structure is
54 returned to which additional recipients and attributes can be added before
57 The data being encrypted is included in the CMS_ContentInfo structure, unless
58 B<CMS_DETACHED> is set in which case it is omitted. This is rarely used in
59 practice and is not supported by SMIME_write_CMS().
61 If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is
62 B<not> complete and outputting its contents via a function that does not
63 properly finalize the B<CMS_ContentInfo> structure will give unpredictable
66 Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(),
67 PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization
68 can be performed by obtaining the streaming ASN1 B<BIO> directly using
71 The recipients specified in B<certs> use a CMS KeyTransRecipientInfo info
72 structure. KEKRecipientInfo is also supported using the flag B<CMS_PARTIAL>
73 and CMS_add0_recipient_key().
75 The parameter B<certs> may be NULL if B<CMS_PARTIAL> is set and recipients
76 added later using CMS_add1_recipient_cert() or CMS_add0_recipient_key().
80 CMS_encrypt() returns either a CMS_ContentInfo structure or NULL if an error
81 occurred. The error can be obtained from ERR_get_error(3).
85 L<ERR_get_error(3)>, L<CMS_decrypt(3)>
89 The B<CMS_STREAM> flag was first supported in OpenSSL 1.0.0.
93 Copyright 2008-2018 The OpenSSL Project Authors. All Rights Reserved.
95 Licensed under the Apache License 2.0 (the "License"). You may not use
96 this file except in compliance with the License. You can obtain a copy
97 in the file LICENSE in the source distribution or at
98 L<https://www.openssl.org/source/license.html>.