KCAPI_AKCIPHER_SIGN_(3)

💖 KCAPI_AKCIPHER_SIGN_AIO — bestie's guide to signing data 💖

okay so this is a page from the libkcapi manual, section 3 (that's the programming interface girlies, iykyk). it's all about kcapi_akcipher_sign_aio and honestly? it's giving ✨one shot✨ energy.

---

✨ NAME ✨

kcapi_akcipher_sign_aio — sign data (asynchronous one shot) 💅

---

🌸 SYNOPSIS 🌸

ssize_t kcapi_akcipher_sign_aio(struct kcapi_handle * handle,
                                struct iovec * iniov,
                                struct iovec * outiov, size_t iovlen,
                                int access);

---

🎀 ARGUMENTS 🎀

• handle — [in] your cipher handle, the main character of this whole situation 🫶
• iniov — [in] head of the scatter-gather list array holding the plaintext, so like, the stuff going in 💌
• outiov — [out] head of the scatter-gather list of the destination buffers filled with ciphertext, aka where the signed stuff lands 🦋
• iovlen — [in] number of scatter-gather list entries, count 'em bestie 🔢
• access — [in] the kernel access type, and you've got choices:
  • KCAPI_ACCESS_HEURISTIC — use internal heuristic for fastest kernel access (the "let the algorithm pick for me" vibe 🧚)
  • KCAPI_ACCESS_VMSPLICE — use vmsplice access
  • KCAPI_ACCESS_SENDMSG — sendmsg access

---

🌈 DESCRIPTION 🌈

The individual scatter-gather list entries are processed with separate invocations of the the given cipher. (yes, "the the" — that's literally what it says, no cap 😭)

The memory should be aligned at the page boundary using posix_memalign(sysconf(_SC_PAGESIZE)). If it is not aligned at the page boundary, the vmsplice call may not send all data to the kernel.

⚠️ okay this one matters: page-boundary alignment is not optional vibes, it's a whole thing. misaligned memory + vmsplice = the kernel might not get all your data. not slay. 💀

return number of bytes signed upon success; a negative errno-style error code if an error occurred. so like, if you get a negative number back, something went wrong bestie — that's your error right there 👑

---

👑 AUTHOR 👑

Stephan Mueller <smueller@chronox.de>

• Author. (he did that. periodt. 💜)

---

💌 COPYRIGHT 💌

and that's the whole page, fr fr. this was libkcapi Manual 1.5.0, dated July 2025 — shoutout to the KCAPI_AKCIPHER_SIGN_(3) girlies, go sign something iconic 🌟💅