5 CMS_encrypt_ex, CMS_encrypt - create a CMS envelopedData structure
9 #include <openssl/cms.h>
11 CMS_ContentInfo *CMS_encrypt_ex(STACK_OF(X509) *certs, BIO *in,
12 const EVP_CIPHER *cipher, unsigned int flags,
13 OSSL_LIB_CTX *libctx, const char *propq);
14 CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in,
15 const EVP_CIPHER *cipher, unsigned int flags);
19 CMS_encrypt_ex() creates and returns a CMS EnvelopedData or
20 AuthEnvelopedData structure. I<certs> is a list of recipient certificates.
21 I<in> is the content to be encrypted. I<cipher> is the symmetric cipher to use.
22 I<flags> is an optional set of flags. The library context I<libctx> and the
23 property query I<propq> are used internally when retrieving algorithms from
26 Only certificates carrying RSA, Diffie-Hellman or EC keys are supported by this
29 EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use
30 because most clients will support it.
32 The algorithm passed in the B<cipher> parameter must support ASN1 encoding of
33 its parameters. If the cipher mode is GCM, then an AuthEnvelopedData structure
34 containing MAC is used. Otherwise an EnvelopedData structure is used. Currently
35 the AES variants with GCM mode are the only supported AEAD algorithms.
37 Many browsers implement a "sign and encrypt" option which is simply an S/MIME
38 envelopedData containing an S/MIME signed message. This can be readily produced
39 by storing the S/MIME signed message in a memory BIO and passing it to
42 The following flags can be passed in the B<flags> parameter.
44 If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are
45 prepended to the data.
47 Normally the supplied content is translated into MIME canonical format (as
48 required by the S/MIME specifications) if B<CMS_BINARY> is set no translation
49 occurs. This option should be used if the supplied data is in binary format
50 otherwise the translation will corrupt it. If B<CMS_BINARY> is set then
51 B<CMS_TEXT> is ignored.
53 OpenSSL will by default identify recipient certificates using issuer name
54 and serial number. If B<CMS_USE_KEYID> is set it will use the subject key
55 identifier value instead. An error occurs if all recipient certificates do not
56 have a subject key identifier extension.
58 If the B<CMS_STREAM> flag is set a partial B<CMS_ContentInfo> structure is
59 returned suitable for streaming I/O: no data is read from the BIO B<in>.
61 If the B<CMS_PARTIAL> flag is set a partial B<CMS_ContentInfo> structure is
62 returned to which additional recipients and attributes can be added before
65 The data being encrypted is included in the CMS_ContentInfo structure, unless
66 B<CMS_DETACHED> is set in which case it is omitted. This is rarely used in
67 practice and is not supported by SMIME_write_CMS().
69 If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is
70 B<not> complete and outputting its contents via a function that does not
71 properly finalize the B<CMS_ContentInfo> structure will give unpredictable
74 Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(),
75 PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization
76 can be performed by obtaining the streaming ASN1 B<BIO> directly using
79 The recipients specified in B<certs> use a CMS KeyTransRecipientInfo info
80 structure. KEKRecipientInfo is also supported using the flag B<CMS_PARTIAL>
81 and CMS_add0_recipient_key().
83 The parameter B<certs> may be NULL if B<CMS_PARTIAL> is set and recipients
84 added later using CMS_add1_recipient_cert() or CMS_add0_recipient_key().
86 CMS_encrypt() is similar to CMS_encrypt_ex() but uses default values
87 of NULL for the library context I<libctx> and the property query I<propq>.
91 CMS_encrypt_ex() and CMS_encrypt() return either a CMS_ContentInfo
92 structure or NULL if an error occurred. The error can be obtained from
97 L<ERR_get_error(3)>, L<CMS_decrypt(3)>
101 The function CMS_encrypt_ex() was added in OpenSSL 3.0.
103 The B<CMS_STREAM> flag was first supported in OpenSSL 1.0.0.
107 Copyright 2008-2020 The OpenSSL Project Authors. All Rights Reserved.
109 Licensed under the Apache License 2.0 (the "License"). You may not use
110 this file except in compliance with the License. You can obtain a copy
111 in the file LICENSE in the source distribution or at
112 L<https://www.openssl.org/source/license.html>.