aes_cmac_preparekey(9)

💅 aes_cmac_preparekey(9) — the Kernel API Manual glow-up

okay bestie so you're in the Kernel API Manual (section 9, kernel space, very demure, very mindful) and you want to prepare a key for AES-CMAC. Say less. 🎀

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✨ NAME ✨

aes_cmac_preparekey — literally just prepare a key for AES-CMAC, that's the whole vibe 🌸

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🦋 SYNOPSIS 🦋

int aes_cmac_preparekey (struct aes_cmac_key *key , const u8 *in_key ,
size_t key_len );

look at that signature. iconic. no notes. 💅

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💜 ARGUMENTS 💜

• key — (output) the key struct you're initializing. it's giving "fill me in bestie" 🫶
• in_key — the raw AES key. the actual key-key. 🔥
• key_len — length of the raw key, in bytes. and ngl, only these three values are supported: AES_KEYSIZE_128, AES_KEYSIZE_192, and AES_KEYSIZE_256. pick one, no freestyling 🚫

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🌈 DESCRIPTION 🌈

so on success, the caller should make sure the prepared key gets zeroized at the end of its lifetime — like, wipe it, don't leave it lying around. you can do this e.g. by calling aes_cmac_zeroize_key or kfree_sensitive. hydrate, moisturize, zeroize. ✨

seriously though, zeroize it. that's the whole point of the note. 🧚

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⭐ CONTEXT ⭐

Any context. yes queen, literally anywhere, no restrictions 💀👑

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🔥 RETURN 🔥

• 0 on success 🎉
• -EINVAL if the given key length is invalid 🙈

and that's it — no other errors are possible. so if you're a caller who always passes a valid key length, you don't even need to check for errors. main character energy fr fr. 💖

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👑 SEE ALSO 👑

Kernel file ./include/crypto/aes-cbc-macs.h, struct aes_cmac_key(9), aes_cmac_zeroize_key(9), struct aes_cmac_ctx(9), aes_cmac_zeroize_ctx(9), aes_xcbcmac_preparekey(9), aes_cmac_init(9), aes_cmac_update(9), aes_cmac_final(9), aes_cmac(9)

go read the whole aes-cmac cinematic universe, iykyk 🍓

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okay that's the page!! brought to you by the good people at ./include/crypto, dated October 2026 — slay, periodt, and don't forget to zeroize your keys 💅💖✨