CMS_encrypt(3)

NAME

        CMS_encrypt - create a CMS envelopedData structure

SYNOPSIS

        #include <openssl/cms.h>

        CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, unsigned int flags);

DESCRIPTION

       CMS_encrypt() creates and returns a CMS EnvelopedData 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.

NOTES

       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.

       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 certifi-
       cates 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().

NOTES

       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
       results.

       Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(),
       PEM_write_bio_CMS_stream() finalize the structure. Alternatively final-
       ization 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_PAR-
       TIAL 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_add0_recipi-
       ent_key().

RETURN VALUES

       CMS_encrypt() returns either a CMS_ContentInfo structure or NULL if an
       error occurred. The error can be obtained from ERR_get_error(3).

SEE ALSO

       ERR_get_error(3), CMS_decrypt(3)

HISTORY

       CMS_decrypt() was added to OpenSSL 0.9.8 The CMS_STREAM flag was first
       supported in OpenSSL 1.0.0.

1.0.2t                            2019-09-10                    CMS_encrypt(3)