SMIME_WRITE_CMS(3ossl)

📦
version 15.1 · 3 versions
, in freebsd 15.1

✨ NAME ✨

okay bestie, this page is SMIME_WRITE_CMS(3ossl) and it's literally about SMIME_write_CMS — converting a CMS structure to S/MIME format. slay.

💻 SYNOPSIS 💻

#include <openssl/cms.h>

int SMIME_write_CMS(BIO *out, CMS_ContentInfo *cms, BIO *data, int flags);

🌸 DESCRIPTION 🌸

SMIME_write_CMS() adds the appropriate MIME headers to a CMS structure to produce an S/MIME message. iconic behavior, honestly.

out is the BIO to write the data to. cms is the appropriate CMS_ContentInfo structure. If streaming is enabled then the content must be supplied in the data argument. flags is an optional set of flags.

🚩 NOTES 🚩

here are the flags you can pass in the flags parameter, bestie:

  • CMS_DETACHED — if this is set then cleartext signing will be used. this option only makes sense for SignedData where CMS_DETACHED is also set when CMS_sign() is called.
  • CMS_TEXT — if this flag is set, MIME headers for type text/plain are added to the content. this only makes sense if CMS_DETACHED is also set.
  • CMS_STREAM — if this flag is set, streaming is performed. this flag should only be set if CMS_STREAM was also set in the previous call to a CMS_ContentInfo creation function.

if cleartext signing is being used and CMS_STREAM is not set, then the data must be read twice: once to compute the signature in CMS_sign() and once to output the S/MIME message. no cap, it's giving two-pass behavior.

if streaming is performed, the content is output in BER format using indefinite length constructed encoding — except in the case of signed data with detached content, where the content is absent and DER format is used. ✨

💀 BUGS 💀

not me exposing the flaw 😭: SMIME_write_CMS() always base64 encodes CMS structures, and there should be an option to disable this.

🎀 RETURN VALUES 🎀

SMIME_write_CMS() returns 1 for success or 0 for failure. periodt.

🦋 SEE ALSO 🦋

the legal tea ☕, exactly as it needs to be:

Copyright 2008-2016 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 <https://www.openssl.org/source/license.html>.

okay that's the whole manual page, bestie 💖 — this one's from OpenSSL 3.5.6, dated 2026-04-07. mwah, go write some S/MIME ✨💅

📦 where this page comes from