/* SPDX-License-Identifier: GPL-2.0 *//* * AES-XTS unauthenticated encryption and decryption * * Copyright 2026 Google LLC */#ifndef _CRYPTO_AES_XTS_H#define _CRYPTO_AES_XTS_H #include <crypto/aes.h>#include <crypto/xts.h> /** * struct aes_xts_key - A key prepared for AES-XTS encryption and decryption * * Note that (depending on the architecture) this typically is around 768 bytes, * which makes it a bit too large to allocate on the stack in most cases. */struct aes_xts_key {	/* private: */	struct aes_key main_key;	struct aes_enckey tweak_key;}; /** * aes_xts_preparekey() - Prepare a key for AES-XTS encryption and decryption * @key: (output) The key structure to initialize * @in_key: The raw AES-XTS key * @key_len: Length of the raw key in bytes * @flags: Optional flag XTS_FORBID_WEAK_KEYS to forbid keys whose two halves *	   are the same. * * Users should use memzero_explicit() to zeroize the key struct at the end of * its lifetime.  (But if this function fails, zeroization is unnecessary.) * * Context: Any context. * Return: * * 0 on success * * -EINVAL if the key is rejected because its length isn't 32, 64, or (when *   FIPS mode isn't enabled) 48; or because its two halves are the same and *   either XTS_FORBID_WEAK_KEYS is given or FIPS mode is enabled. */int __must_check aes_xts_preparekey(struct aes_xts_key *key, const u8 *in_key,				    size_t key_len, int flags); /** * aes_xts_encrypt() - Encrypt data using AES-XTS * @dst: The destination buffer.  Can be in-place or out-of-place.  For other *	 overlaps the behavior is unspecified. * @src: The source data * @len: Number of bytes to encrypt.  On non-final calls it must be a nonzero *	 multiple of AES_BLOCK_SIZE.  On the final call it can be any value >= *	 AES_BLOCK_SIZE, i.e. ciphertext stealing is supported. * @tweak: The tweak.  It is updated with the next value, unless @len isn't a *	   multiple of AES_BLOCK_SIZE in which case the value is unspecified. * @key: The key, already prepared using aes_xts_preparekey() * @cont: %false to begin encrypting a new message (do the tweak encryption); *	  %true to continue encrypting a message (skip tweak encryption) * * This supports both one-shot and incremental encryption.  On the first call, * pass @cont = %false.  On any later calls, pass @cont = %true and the updated * @tweak; all earlier @len must have been multiples of AES_BLOCK_SIZE. * * Context: Any context. */void aes_xts_encrypt(u8 *dst, const u8 *src, size_t len,		     u8 tweak[at_least AES_BLOCK_SIZE],		     const struct aes_xts_key *key, bool cont); /** * aes_xts_decrypt() - Decrypt data using AES-XTS * @dst: The destination buffer.  Can be in-place or out-of-place.  For other *	 overlaps the behavior is unspecified. * @src: The source data * @len: Number of bytes to decrypt.  On non-final calls it must be a nonzero *	 multiple of AES_BLOCK_SIZE.  On the final call it can be any value >= *	 AES_BLOCK_SIZE, i.e. ciphertext stealing is supported. * @tweak: The tweak.  It is updated with the next value, unless @len isn't a *	   multiple of AES_BLOCK_SIZE in which case the value is unspecified. * @key: The key, already prepared using aes_xts_preparekey() * @cont: %false to begin decrypting a new message (do the tweak encryption); *	  %true to continue decrypting a message (skip tweak encryption) * * This supports both one-shot and incremental decryption.  On the first call, * pass @cont = %false.  On any later calls, pass @cont = %true and the updated * @tweak; all earlier @len must have been multiples of AES_BLOCK_SIZE. * * Context: Any context. */void aes_xts_decrypt(u8 *dst, const u8 *src, size_t len,		     u8 tweak[at_least AES_BLOCK_SIZE],		     const struct aes_xts_key *key, bool cont); #endif /* _CRYPTO_AES_XTS_H */