EVP_MAC-CMAC(7ossl)

📦
version 15.1 · 3 versions
, in freebsd 15.1

✨ NAME ✨

EVP_MAC-CMAC — the CMAC EVP_MAC implementation, bestie 💅 (this is the 7ossl manual page, so you know it's the real deal from OpenSSL)

🎀 SYNOPSIS 🎀

So like. You want CMAC. Through the EVP_MAC API. That's it, that's the whole vibe 🦋

💖 DESCRIPTION 💖

Okay so picture this: this implementation gives you support for computing CMAC MACs through the EVP_MAC API. Slay.

And the way it does that? It uses EVP_CIPHER functions to get access to the underlying cipher. Iconic behavior, no cap 🔥

👑 Identity

This implementation is identified with this name and these properties, and you use them with EVP_MAC_fetch():

"CMAC", "provider=default" or "provider=fips"

That's the whole identity check. Main character energy fr fr ✨

🌸 Supported parameters

The general description of these parameters lives in "PARAMETERS" in EVP_MAC(3) — go peek if you want the big picture, bestie.

The following parameter can be set with EVP_MAC_CTX_set_params():

  • "key" (OSSL_MAC_PARAM_KEY) <octet string> — Sets the MAC key. Setting this parameter is literally identical to passing a key to EVP_MAC_init(3). Same thing, different font 💅
  • "cipher" (OSSL_MAC_PARAM_CIPHER) <UTF8 string> — Sets the name of the underlying cipher to be used. Heads up though: the mode of the cipher must be CBC. Not optional. That's the rule 🙈
  • "properties" (OSSL_MAC_PARAM_PROPERTIES) <UTF8 string> — Sets the properties to be queried when trying to fetch the underlying cipher. This one must be given together with the cipher naming parameter to be considered valid — they're a package deal, iykyk 🫶
  • "encrypt-check" (OSSL_CIPHER_PARAM_FIPS_ENCRYPT_CHECK) <integer> — This option is used by the OpenSSL FIPS provider. If required, this parameter should be set before EVP_MAC_init(). The default value of 1 causes an error when an unapproved Triple-DES encryption operation is triggered. Setting this to 0 will ignore the error and set the approved "fips-indicator" to 0. And real talk: this option breaks FIPS compliance if it causes the approved "fips-indicator" to return 0 💀
Ok bestie, that FIPS compliance thing? Not a drill. Say it with me: the option breaks FIPS compliance if it makes "fips-indicator" return 0.

The following parameters can be retrieved with EVP_MAC_CTX_get_params():

  • "size" (OSSL_MAC_PARAM_SIZE) <unsigned integer> — The "size" parameter can also be retrieved with EVP_MAC_CTX_get_mac_size(). And the length of the "size" parameter is equal to that of an unsigned int. Little details, but they eat ⭐
  • "block-size" (OSSL_MAC_PARAM_BLOCK_SIZE) <unsigned integer> — Gets the MAC block size. The "block-size" parameter can also be retrieved with EVP_MAC_CTX_get_block_size(). Two ways in, same destination, we love a shortcut 🌈
  • "fips-indicator" (OSSL_CIPHER_PARAM_FIPS_APPROVED_INDICATOR) <integer> — This option is used by the OpenSSL FIPS provider. It's a getter that returns 1 if the operation is FIPS approved, or 0 otherwise. This may be used after calling EVP_MAC_final(). And yeah — it may return 0 if the "encrypt-check" option is set to 0. Cause and effect, babes 🍓

🦋 SEE ALSO 🦋

Go read them, they're all connected, it's giving lore ✨

Copyright 2018-2024 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>.

And that's the page, bestie 🎀🫶 — brought to you by version 3.5.6, dated 2026-04-07, filed under EVP_MAC-CMAC(7ossl). Go forth and CMAC responsibly 💅✨

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