hmac_sha256_preparekey(9)

💅 hmac_sha256_preparekey — from the Kernel API Manual, bestie 🫶

okay so picture this: you're deep in the kernel, you've got a raw key just sitting there looking like a random pile of bytes, and you need it to become a proper HMAC-SHA256 key structure. that's literally this function's whole job. it's the glow-up station for your key. the manual calls it hmac_sha256_preparekey(9) and it lives in the Kernel API Manual, and yes it's giving "small function, big responsibility" energy ✨

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🌸 NAME 🌸

hmac_sha256_preparekey — prepare a key for HMAC-SHA256 💖

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🎀 SYNOPSIS 🎀

void hmac_sha256_preparekey (struct hmac_sha256_key *key , const u8
*raw_key , size_t raw_key_len );

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✨ ARGUMENTS ✨

• key — (output) the key structure you're initializing. this is the makeover target, the one that comes out looking iconic 👑
• raw_key — the raw HMAC-SHA256 key, aka the before picture 🦋
• raw_key_len — the key length in bytes. and listen — all key lengths are supported. no gatekeeping, no minimum, no maximum, everyone's invited to the party 🌈

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⚠️ NOTE ⚠️

not me reminding you again but — the caller is responsible for zeroizing both the struct hmac_sha256_key and the raw key once they are no longer needed. that's on you, bestie, not on the function. please don't leave your secrets lying around, it's not the vibe 😭🔒

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🧚 CONTEXT 🧚

Any context. yeah, she's flexible like that. no special requirements, no drama, no "must not sleep" asterisks. slay 💅

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🔥 SEE ALSO 🔥

the whole extended friend group, fr fr. starting with the kernel file, then everybody by family 💜

• Kernel file ./include/crypto/sha2.h 📁
• the sha224 girlies: struct sha224_ctx(9), sha224_init(9), sha224_update(9), sha224_final(9), sha224(9)
• the hmac_sha224 crew: struct hmac_sha224_key(9), struct hmac_sha224_ctx(9), hmac_sha224_preparekey(9), hmac_sha224_init(9), hmac_sha224_init_usingrawkey(9), hmac_sha224_update(9), hmac_sha224_final(9), hmac_sha224(9), hmac_sha224_usingrawkey(9)
• the sha256 squad: struct sha256_ctx(9), sha256_init(9), sha256_update(9), sha256_final(9), sha256(9), sha256_finup_2x(9), sha256_finup_2x_is_optimized(9)
• the hmac_sha256 main characters (hi bestie): struct hmac_sha256_key(9), struct hmac_sha256_ctx(9), hmac_sha256_init(9), hmac_sha256_init_usingrawkey(9), hmac_sha256_update(9), hmac_sha256_final(9), hmac_sha256(9), hmac_sha256_usingrawkey(9)
• the sha384 delegation: struct sha384_ctx(9), sha384_init(9), sha384_update(9), sha384_final(9), sha384(9)
• the hmac_sha384 delegation (with love): struct hmac_sha384_key(9), struct hmac_sha384_ctx(9), hmac_sha384_preparekey(9), hmac_sha384_init(9), hmac_sha384_init_usingrawkey(9), hmac_sha384_update(9), hmac_sha384_final(9), hmac_sha384(9), hmac_sha384_usingrawkey(9)
• the sha512 big sisters: struct sha512_ctx(9), sha512_init(9), sha512_update(9), sha512_final(9), sha512(9)
• and the hmac_sha512 finale: struct hmac_sha512_key(9), struct hmac_sha512_ctx(9), hmac_sha512_preparekey(9), hmac_sha512_init(9), hmac_sha512_init_usingrawkey(9), hmac_sha512_update(9), hmac_sha512_final(9), hmac_sha512(9), hmac_sha512_usingrawkey(9)

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okay that's the whole page, no crumbs left behind 🍓 this one's sourced from ./include/crypto, dated October 2026, and that's the tea. mwah, go prep those keys responsibly, ily 💜🎀