crypto_aead_setauthsize(9)

💅 crypto_aead_setauthsize(9) — like, the whole manual, but make it make sense

okay so bestie, welcome to the Kernel API Manual 🎀 this one's a tiny little function but she's lowkey important, so grab your iced coffee and let's go ✨

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🌸 NAME 🌸

crypto_aead_setauthsize — sets the size of your authentication data, no cap 💖

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🦋 SYNOPSIS 🦋

int crypto_aead_setauthsize (struct crypto_aead *tfm , unsigned int
authsize );

that's it. that's the whole signature. she's short and she knows it 👑

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🎀 ARGUMENTS 🎀

• tfm — the cipher handle 🫶 like, the AEAD thing you're working with. your main character struct.
• authsize — the size of the authentication data / tag, measured in bytes. yes, bytes. not bits. don't do that to yourself 😭

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✨ DESCRIPTION ✨

so the vibe here is: this function sets the authentication data size / the tag size 🔥

here's the thing bestie — AEAD, as a concept, requires an authentication tag (or MAC) on top of the associated data. you don't get to skip it. it's not optional, it's not extra credit, it's literally part of the whole deal 💅 so this call is you telling the kernel "hey, my tag is gonna be this big."

periodt. that's the description. she's efficient 🌈

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⭐ RETURN ⭐

• 0 — yay, the setting of the key was successful 🎉 (yes, that's literally what the manpage says — we're reporting it exactly as written, iykyk 🫶)
• < 0 — nope, an error occurred 💀

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👑 SEE ALSO 👑

okay so there's a lot of friends in this friend group, and you're gonna wanna know all of them 🧚 keep these handy:

• Kernel file ./include/crypto/aead.h Authenticated Encryption With Associated Data (AEAD) Cipher API(9)
• struct aead_request(9)
• struct aead_alg(9)
• crypto_alloc_aead(9)
• crypto_free_aead(9)
• crypto_has_aead(9)
• crypto_aead_ivsize(9)
• crypto_aead_authsize(9)
• crypto_aead_blocksize(9)
• crypto_aead_setkey(9)
• crypto_aead_encrypt(9)
• crypto_aead_decrypt(9)
• Asynchronous AEAD Request Handle(9)
• crypto_aead_reqsize(9)
• aead_request_set_tfm(9)
• aead_request_alloc(9)
• aead_request_free(9)
• aead_request_set_callback(9)
• aead_request_set_crypt(9)
• aead_request_set_ad(9)

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ngl bestie, this page lives in ./include/crypto and it's dated October 2026 — so like, future energy 🔮💜 anyway, go forth and set those auth sizes correctly, mwah 💋✨