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CMS_ENCRYPT(3ossl)		    OpenSSL		    CMS_ENCRYPT(3ossl)

       CMS_encrypt_ex, CMS_encrypt - create a CMS envelopedData	structure

	#include <openssl/cms.h>

	CMS_ContentInfo	*CMS_encrypt_ex(STACK_OF(X509) *certs, BIO *in,
					const EVP_CIPHER *cipher, unsigned int flags,
					OSSL_LIB_CTX *libctx, const char *propq);
	CMS_ContentInfo	*CMS_encrypt(STACK_OF(X509) *certs, BIO	*in,
				     const EVP_CIPHER *cipher, unsigned	int flags);

       CMS_encrypt_ex()	creates	and returns a CMS EnvelopedData	or
       AuthEnvelopedData structure. certs is a list of recipient certificates.
       in is the content to be encrypted. cipher is the	symmetric cipher to
       use.  flags is an optional set of flags.	The library context libctx and
       the property query propq	are used internally when retrieving algorithms
       from providers.

       Only certificates carrying RSA, Diffie-Hellman or EC keys are supported
       by this function.

       EVP_des_ede3_cbc() (triple DES) is the algorithm	of choice for S/MIME
       use because most	clients	will support it.

       The algorithm passed in the cipher parameter must support ASN1 encoding
       of its parameters. If the cipher	mode is	GCM, then an AuthEnvelopedData
       structure containing MAC	is used. Otherwise an EnvelopedData structure
       is used.	Currently the AES variants with	GCM mode are the only
       supported AEAD algorithms.

       Many browsers implement a "sign and encrypt" option which is simply an
       S/MIME envelopedData containing an S/MIME signed	message. This can be
       readily produced	by storing the S/MIME signed message in	a memory BIO
       and passing it to CMS_encrypt().

       The following flags can be passed in the	flags parameter.

       If the CMS_TEXT flag is set MIME	headers	for type text/plain are
       prepended to the	data.

       Normally	the supplied content is	translated into	MIME canonical format
       (as required by the S/MIME specifications) if CMS_BINARY	is set no
       translation occurs. This	option should be used if the supplied data is
       in binary format	otherwise the translation will corrupt it. If
       CMS_BINARY is set then CMS_TEXT is ignored.

       OpenSSL will by default identify	recipient certificates using issuer
       name and	serial number. If CMS_USE_KEYID	is set it will use the subject
       key identifier value instead. An	error occurs if	all recipient
       certificates do not have	a subject key identifier extension.

       If the CMS_STREAM flag is set a partial CMS_ContentInfo structure is
       returned	suitable for streaming I/O: no data is read from the BIO in.

       If the CMS_PARTIAL flag is set a	partial	CMS_ContentInfo	structure is
       returned	to which additional recipients and attributes can be added
       before finalization.

       The data	being encrypted	is included in the CMS_ContentInfo structure,
       unless CMS_DETACHED is set in which case	it is omitted. This is rarely
       used in practice	and is not supported by	SMIME_write_CMS().

       If the flag CMS_STREAM is set the returned CMS_ContentInfo structure is
       not complete and	outputting its contents	via a function that does not
       properly	finalize the CMS_ContentInfo structure will give unpredictable

       Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(),
       PEM_write_bio_CMS_stream() finalize the structure. Alternatively
       finalization can	be performed by	obtaining the streaming	ASN1 BIO
       directly	using BIO_new_CMS().

       The recipients specified	in certs use a CMS KeyTransRecipientInfo info
       structure. KEKRecipientInfo is also supported using the flag
       CMS_PARTIAL and CMS_add0_recipient_key().

       The parameter certs may be NULL if CMS_PARTIAL is set and recipients
       added later using CMS_add1_recipient_cert() or

       CMS_encrypt() is	similar	to CMS_encrypt_ex() but	uses default values of
       NULL for	the library context libctx and the property query propq.

       CMS_encrypt_ex()	and CMS_encrypt() return either	a CMS_ContentInfo
       structure or NULL if an error occurred. The error can be	obtained from

       ERR_get_error(3), CMS_decrypt(3)

       The function CMS_encrypt_ex() was added in OpenSSL 3.0.

       The CMS_STREAM flag was first supported in OpenSSL 1.0.0.

       Copyright 2008-2020 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the Apache License 2.0 (the "License").  You may not use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at

3.0.0+quic			  2021-09-08		    CMS_ENCRYPT(3ossl)


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