Updated: 2021/Apr/14

SMIME_read_CMS(3)                   OpenSSL                  SMIME_read_CMS(3)

       SMIME_read_CMS - parse S/MIME message

       libcrypto, -lcrypto

        #include <openssl/cms.h>

        CMS_ContentInfo *SMIME_read_CMS(BIO *in, BIO **bcont);

       SMIME_read_CMS() parses a message in S/MIME format.

       in is a BIO to read the message from.

       If cleartext signing is used then the content is saved in a memory bio
       which is written to *bcont, otherwise *bcont is set to NULL.

       The parsed CMS_ContentInfo structure is returned or NULL if an error

       If *bcont is not NULL then the message is clear text signed. *bcont can
       then be passed to CMS_verify() with the CMS_DETACHED flag set.

       Otherwise the type of the returned structure can be determined using

       To support future functionality if bcont is not NULL *bcont should be
       initialized to NULL. For example:

        BIO *cont = NULL;
        CMS_ContentInfo *cms;

        cms = SMIME_read_CMS(in, &cont);

       The MIME parser used by SMIME_read_CMS() is somewhat primitive.  While
       it will handle most S/MIME messages more complex compound formats may
       not work.

       The parser assumes that the CMS_ContentInfo structure is always base64
       encoded and will not handle the case where it is in binary format or
       uses quoted printable format.

       The use of a memory BIO to hold the signed content limits the size of
       message which can be processed due to memory restraints: a streaming
       single pass option should be available.

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

       ERR_get_error(3), CMS_type(3), SMIME_read_CMS(3), CMS_sign(3),
       CMS_verify(3), CMS_encrypt(3), CMS_decrypt(3)

       Copyright 2008-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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

1.1.1i                            2018-09-23                 SMIME_read_CMS(3)