CMS_encrypt - create a CMS envelopedData structure
CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, unsigned int flags);
Only certificates carrying RSA keys are supported so the recipient certificates supplied to this function must all contain RSA public keys, though they do not have to be signed using the RSA algorithm.
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
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,
CMS_DETACHED is set in which case it is omitted. This is rarely used in practice and is
not supported by
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
The recipients specified in certs use a CMS KeyTransRecipientInfo info structure. KEKRecipientInfo is also
supported using the flag CMS_PARTIAL
The parameter certs may be NULL if CMS_PARTIAL is set and recipients added later using