hmac_sha1_update(9)

💅 hmac_sha1_update — the kernel API manual edition ✨

okay so bestie, gather round, because today we're talking about hmac_sha1_update(9) from the Kernel API Manual — yes, the actual kernel API manual, not some random wiki page, we're fancy here 🎀

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🌸 NAME 🌸

hmac_sha1_update — literally just feeds more message data into an HMAC-SHA1 context, no cap 💖

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✨ SYNOPSIS ✨

void hmac_sha1_update (struct hmac_sha1_ctx *ctx , const u8 *data ,
size_t data_len );

that's the whole signature, character for character, don't @ me 🫶

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🦋 ARGUMENTS 🦋

• ctx — the HMAC context you're updating. important: it must have been initialized already. like, this is not a "surprise, initialize it for you" situation, it's a "you should've done that already" situation 😭 please initialise your contexts bestie.
• data — the message data itself. the actual bytes. the content. the main character of this function 🌟
• data_len — how long data is, measured in bytes. extremely standard, extremely necessary 💅

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💜 DESCRIPTION 💜

so here's the vibe: you call this to update an HMAC-SHA1 context with message data.

and the iconique part? this can be called any number of times. 🌈 zero. one. twelve. a hundred. the function does not care, it is unbothered, it is thriving 👑

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⭐ CONTEXT ⭐

Any context. fr fr, that's what it says — no restrictions, no special context required, just vibes ✨

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🍓 SEE ALSO 🍓

sibling functions and related structs, all linked together like one big crypto family reunion 🧚:

• Kernel file ./include/crypto/sha1.h
• struct sha1_ctx(9)
• sha1_init(9)
• sha1_update(9)
• sha1_final(9)
• sha1(9)
• struct hmac_sha1_key(9)
• struct hmac_sha1_ctx(9)
• hmac_sha1_preparekey(9)
• hmac_sha1_init(9)
• hmac_sha1_init_usingrawkey(9)
• hmac_sha1_final(9)
• hmac_sha1(9)
• hmac_sha1_usingrawkey(9)

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quick reminder bestie: ctx must have been initialized before you call this. that's not me being dramatic, that's literally in the arguments section. don't come for me, come for the docs 💀

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🎀 that's the whole page!! 🎀 this icon was brought to you by the ./include/crypto source, the October 2026 date stamp, and the Kernel API Manual itself — mwah, love u, go initialise ur contexts 💖✨🦋💅