BIO_NEW_CMS(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

🎀 NAME 🎀 — the vibe check

okay so bestie, welcome to BIO_NEW_CMS(3ossl) — that’s the OpenSSL manual page for this absolutely iconic little thing: BIO_new_CMS, aka the CMS streaming filter BIO 💅✨

✨ SYNOPSIS ✨

#include <openssl/cms.h>

BIO *BIO_new_CMS(BIO *out, CMS_ContentInfo *cms);

💖 DESCRIPTION 💖

So BIO_new_CMS() returns a streaming filter BIO chain based on cms. The output of the filter is written to out. Any data written to the chain is automatically translated to a BER format CMS structure of the appropriate type. She’s literally doing the translation for you, no cap 🫶

🌸 NOTES 🌸

The chain returned by this function behaves like a standard filter BIO. It supports non blocking I/O. Content is processed and streamed on the fly and not all held in memory at once: so it is possible to encode very large structures. After all content has been written through the chain, BIO_flush() must be called to finalise the structure. 🧚

⚠️ bestie, do not forget this: the CMS_STREAM flag must be included in the corresponding flags parameter of the cms creation function.

If an application wishes to write additional data to out, BIOs should be removed from the chain using BIO_pop() and freed with BIO_free() until out is reached. If no additional data needs to be written, BIO_free_all() can be called to free up the whole chain. 🎀

Any content written through the filter is used verbatim: no canonical translation is performed.

It is possible to chain multiple BIOs to, for example, create a triple wrapped signed, enveloped, signed structure. In this case it is the applications responsibility to set the inner content type of any outer CMS_ContentInfo structures. 👑

Large numbers of small writes through the chain should be avoided as this will produce an output consisting of lots of OCTET STRING structures. Prepending a BIO_f_buffer() buffering BIO will prevent this. 💡

💀 BUGS 💀

There is currently no corresponding inverse BIO: i.e. one which can decode a CMS structure on the fly. Yeah… that’s the situation, bestie 😭

🌈 RETURN VALUES 🌈

BIO_new_CMS() returns a BIO chain when successful or NULL if an error occurred. The error can be obtained from ERR_get_error(3). 🙈

🦋 SEE ALSO 🦋

⭐ HISTORY ⭐

The BIO_new_CMS() function was added in OpenSSL 1.0.0. vintage icon behavior, honestly 💜

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>.

That’s the whole vibe — OpenSSL 3.5.0, dated 2026-09-25. bye bestie, go stream those CMS structures responsibly 💅✨

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