aes_cbc_decrypt(9)

💅 aes_cbc_decrypt(9) — like, the Kernel API Manual bestie, we're doing crypto today ✨

okay so picture this: you've got ciphertext and you need it gone, decoded, un-scrambled. That's this function. It lives in the Kernel API Manual, it's giving main character energy, and it's literally the decrypt half of AES-CBC. Let's go 🎀

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🌸 NAME 🌸

aes_cbc_decrypt — decrypt data using AES-CBC. that's it, that's the whole vibe 💖

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✨ SYNOPSIS ✨

void aes_cbc_decrypt (u8 *dst , const u8 *src , size_t len , u8
iv[static AES_BLOCK_SIZE] , const struct aes_key *key );

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🫶 ARGUMENTS 🫶

• dst — the destination buffer, aka where the pretty plaintext goes. it can be in-place or out-of-place, both slay. but for other overlaps?? the behavior is unspecified — so like, don't, bestie, that's not the move 🙈
• src — the source data. the ciphertext. the mysterious one 👑
• len — how many bytes you wanna decrypt. must be a multiple of AES_BLOCK_SIZE — no cap, it's non-negotiable 💀
• iv — the initialization vector. it gets updated with the next value, i.e. the last ciphertext block. (or left unchanged if len == 0 — yes, zero, nothing happens, iconic ⭐)
• key — the key, which you already prepared using aes_preparekey. don't come in here with a raw un-prepped key, that's not the vibe 🔥

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🌈 DESCRIPTION 🌈

so this one supports incremental decryption, which is lowkey the coolest part. the way it works: the length of each chunk must be a multiple of AES_BLOCK_SIZE, and you gotta pass the updated iv back in every single time. keep the iv in sync, keep the vibes in sync, periodt 💅

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🦋 CONTEXT 🦋

any context. literally any. go off wherever, she doesn't care 🌸

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💜 SEE ALSO 💜

• Kernel file ./include/crypto/aes-cbc.h
• aes_cbc_encrypt(9) — the sibling, the other half, the yin to this yang 🧚
• aes_cbc_cts_encrypt(9)
• aes_cbc_cts_decrypt(9)

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and that's the page, bestie!! 🍓 sourced straight from ./include/crypto, dated October 2026, and signed off with a little 💖 — go decrypt something cute, and remember: AES_BLOCK_SIZE or it didn't happen 😭✨