krb5_derive_Ki(9)

💜 krb5_derive_Ki(9) — a Kernel API Manual moment

okay so bestie, we're in the Kernel API Manual today and the main character is krb5_derive_Ki(9) — say it with me, it's giving crypto, it's giving Kerberos, it's giving "I derive keys and I do it flawlessly." ✨

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🌸 NAME 🌸

krb5_derive_Ki — derive key Ki and install it into a hash 🎀

like, that's the whole vibe. derive Ki. install it. done. periodt.

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🦋 SYNOPSIS 🦋

int krb5_derive_Ki (const struct krb5_enctype *krb5 , const struct
       krb5_buffer *TK , u32 usage , struct krb5_buffer *key , gfp_t gfp );

she takes five arguments and returns an int, no cap 💅

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💖 ARGUMENTS 💖

• krb5 — the encryption type to use 🔥 like, which flavor of crypto are we working with, bestie
• TK — the base key 🗝️ the OG key that everything gets derived from
• usage — the key usage number 🔢 a u32, so she's got range
• key — a prepped buffer to store the key into 🎀 prepped, okay? it has to already be ready, don't come at her with a raw un-prepped buffer
• gfp — allocation restrictions 🌈 the rules about how memory gets allocated, iykyk

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✨ DESCRIPTION ✨

So what she actually does: she derives the Kerberos Ki integrity checksum key 👑 That's the Ki. That's the whole assignment.

Then the key gets stored into the prepared buffer — the one you handed her in key — and that's it. She's not doing extra. She's not doing too much. She's doing exactly this and she's eating 💅

lowkey important reminder from the top: that buffer needs to be prepared before you call her. She's storing into it, not conjuring it out of thin air 🫶

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🌈 SEE ALSO 🌈

• Kernel file ./crypto/krb5/krb5_kdf.c 📁
• crypto_krb5_calc_PRFplus(9)
• krb5_derive_Kc(9)
• krb5_derive_Ke(9)

the whole key-derivation friend group honestly, go say hi to Kc and Ke too, they're iconic in their own right 🦋

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and that's the page!! source situation is ./crypto/krb5, dated October 2026, and yes she's still krb5_derive_Ki(9) bestie, she never changed 💖 mwah, go derive some keys 🎀✨