CMS_encrypt(3)

CMS_encrypt(3)               OpenSSL               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 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.

1.0.2t               Last change: 2019-09-10                    1

CMS_encrypt(3)               OpenSSL               CMS_encrypt(3)

     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 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_add0_recipient_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               Last change: 2019-09-10                    2