aes_xts_preparekey(9)

✨ aes_xts_preparekey ✨ (section 9, from the Kernel API Manual, bestie 💅)

okay so listen — this is aes_xts_preparekey, and it's literally the glow-up your raw key needs before it can do AES-XTS encryption and decryption. 🎀

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🌸 NAME 🌸

aes_xts_preparekey — prepare a key for AES-XTS encryption and decryption. that's it, that's the job, and it ate. 💖

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✨ SYNOPSIS ✨

int aes_xts_preparekey (struct aes_xts_key *key , const u8 *in_key ,
size_t key_len , int flags );

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🦋 ARGUMENTS 🦋

• key — (output) the key structure to initialize. this is your main character struct, the one getting all dressed up. 👑
• in_key — the raw AES-XTS key. the before picture. 🙈
• key_len — length of the raw key, in bytes. sizes matter, ikyk. 📏
• flags — optional flag XTS_FORBID_WEAK_KEYS, which does exactly what it says on the tin: it forbids keys whose two halves are the same. no identical-twin keys on its watch, no cap. 🚫

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💜 DESCRIPTION 💜

okay so here's the self-care routine: users should use memzero_explicit to zeroize the key struct at the end of its lifetime. wipe it down, cleanse it, keep it out of memory's camera roll. 🧖‍♀️

but — and this is the plot twist — if this function fails, zeroization is unnecessary. nothing to scrub if nothing ever got set up, periodt. 💀

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🌈 CONTEXT 🌈

Any context. any. it's giving low-maintenance icon, fr fr. ✨

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🔥 RETURN 🔥

• 0 on success. slay, we love a clean win. 🎉
• -EINVAL if the key is rejected, and there are two whole reasons that can happen:
  • because its length isn't 32, 64, or (when FIPS mode isn't enabled) 48; or
  • because its two halves are the same and either XTS_FORBID_WEAK_KEYS is given or FIPS mode is enabled. 🔴

ngl, get the length or the halves wrong and it's an instant -EINVAL, no second chances. read the requirements before you slide into the function call. 😭

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👀 SEE ALSO 👀

Kernel file ./include/crypto/aes-xts.h, struct aes_xts_key(9), aes_xts_encrypt(9), aes_xts_decrypt(9) — go read the whole friend group, they're all iconic. 🫶

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and that's the page, bestie! 💖 signed off by ./include/crypto, dated October 2026 — mwah, catch you in section 9. 💅⭐🌸