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https://github.com/linux-msm/laptops-kernel.git
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Eric Biggers
1f2d69a31a
Add support for AES-CTR and AES-XCTR to the crypto library. These will be used to provide streamlined implementations of the "ctr(aes)" and "xctr(aes)" crypto_skcipher algorithms. Most users of "ctr(aes)" will also be able to switch to the library, which as usual will be simpler and faster, e.g.: - net/mac80211/fils_aead.c - net/mac802154/llsec.c As usual, the architecture-optimized AES-CTR and AES-XCTR code will be migrated into the library as well (using the hooks provided in this commit), eliminating lots of repetitive boilerplate code. This is also a prerequisite for supporting AES-GCM, AES-CCM, and AES-HCTR2 in the crypto library. Initial test coverage is provided by the crypto_skcipher support added in a later commit. I'm planning a KUnit test suite as well. Reviewed-by: Thomas Huth <thuth@redhat.com> Link: https://patch.msgid.link/20260715221153.246410-5-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org>
66 lines
2.5 KiB
C
66 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* AES-CTR and AES-XCTR stream ciphers
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*
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* Copyright 2026 Google LLC
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*/
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#ifndef _CRYPTO_AES_CTR_H
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#define _CRYPTO_AES_CTR_H
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#include <crypto/aes.h>
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/**
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* aes_ctr() - AES-CTR en/decryption
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* @dst: The destination buffer. Can be in-place or out-of-place. For other
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* overlaps the behavior is unspecified.
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* @src: The source data
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* @len: Number of bytes to en/decrypt
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* @ctr: The counter. It will be incremented by ceil(@len / AES_BLOCK_SIZE).
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* @key: The key, already prepared using aes_preparekey() or aes_prepareenckey()
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*
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* This implements AES in counter mode with a 128-bit big endian counter.
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*
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* This exists only for use by the implementation of modes built on top of CTR
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* (e.g., GCM and CCM) and some legacy protocols that use CTR mode directly.
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* Callers are expected to know how to use CTR mode appropriately, including
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* choosing (key, counter) pairs appropriately to avoid keystream reuse.
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*
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* This supports incremental en/decryption. The length of each non-final chunk
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* must be a multiple of AES_BLOCK_SIZE, and the updated @ctr must be passed in
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* each time.
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*
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* Context: Any context.
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*/
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void aes_ctr(u8 *dst, const u8 *src, size_t len,
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u8 ctr[at_least AES_BLOCK_SIZE], aes_encrypt_arg key);
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/**
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* aes_xctr() - AES-XCTR en/decryption
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* @dst: The destination buffer. Can be in-place or out-of-place. For other
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* overlaps the behavior is unspecified.
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* @src: The source data
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* @len: Number of bytes to en/decrypt
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* @ctr: The block counter (in host endianness). For the first call, set it to
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* 1. It will be incremented by ceil(@len / AES_BLOCK_SIZE).
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* @iv: The initialization vector
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* @key: The key, already prepared using aes_preparekey() or aes_prepareenckey()
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*
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* This implements AES in XOR Counter mode, as specified in the paper
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* "Length-preserving encryption with HCTR2"
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* (https://eprint.iacr.org/2021/1441.pdf).
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*
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* This exists only for use by the implementation of modes built on top of XCTR.
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* Callers are expected to know how to use XCTR mode appropriately, including
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* choosing (key, IV) pairs appropriately to avoid keystream reuse.
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*
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* This supports incremental en/decryption. The length of each non-final chunk
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* must be a multiple of AES_BLOCK_SIZE, and the updated @ctr must be passed in
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* each time.
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*
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* Context: Any context.
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*/
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void aes_xctr(u8 *dst, const u8 *src, size_t len, u64 *ctr,
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const u8 iv[at_least AES_BLOCK_SIZE], aes_encrypt_arg key);
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#endif /* _CRYPTO_AES_CTR_H */
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