sha256_finup_2x(9)

💅 sha256_finup_2x(9) — like, the Kernel API Manual page you actually want to read ✨

okay so picture this: you're gonna hash two things at once, and this function is the moment. 🫶

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✨ NAME ✨

sha256_finup_2x — compute two SHA-256 digests from a common initial context. On some CPUs, this is faster than sequentially computing each digest. no cap, that's literally the whole pitch 💫

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🎀 SYNOPSIS 🎀

void sha256_finup_2x (const struct sha256_ctx *ctx , const u8 *data1 ,
const u8 *data2 , size_t len , u8 out1[static SHA256_DIGEST_SIZE] , u8
out2[static SHA256_DIGEST_SIZE] );

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🌸 ARGUMENTS 🌸

• ctx — an optional initial context, which may have already processed data. If NULL, a default initial context is used (equivalent to sha256_init). so yes bestie, optional, it's giving "bring your own state or don't, we got you" 💖
• data1 — data for the first message
• data2 — data for the second message
• len — the length of each of data1 and data2, in bytes (that's each, not total, don't come for me 🙈)
• out1 — (output) the first SHA-256 message digest
• out2 — (output) the second SHA-256 message digest

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🦋 CONTEXT 🦋

Any context. that's the whole section. iconic, honestly 👑

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🔥 SEE ALSO 🔥

the whole friend group, fr fr — starting with the 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 girlies: 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 girlies: struct sha256_ctx(9), sha256_init(9), sha256_update(9), sha256_final(9), sha256(9), sha256_finup_2x_is_optimized(9) — that last one is the vibe check, check it before you assume anything is optimized 😌
• the hmac_sha256 girlies: struct hmac_sha256_key(9), struct hmac_sha256_ctx(9), hmac_sha256_preparekey(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 girlies: struct sha384_ctx(9), sha384_init(9), sha384_update(9), sha384_final(9), sha384(9)
• the hmac_sha384 girlies: 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 girlies: struct sha512_ctx(9), sha512_init(9), sha512_update(9), sha512_final(9), sha512(9)
• the hmac_sha512 girlies: 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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reminder bestie: len is the length of each buffer, and both out1 and out2 are SHA256_DIGEST_SIZE bytes. write outside that and it's not a slay, it's a buffer overflow 💀

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kisses from the ./include/crypto directory, October 2026 edition 💜✨ mwah, go hash something twice as fast 🎀