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14e15c71d7
Add support for the NH "almost-universal hash function" to lib/crypto/, specifically the variant of NH used in Adiantum. This will replace the need for the "nhpoly1305" crypto_shash algorithm. All the implementations of "nhpoly1305" use architecture-optimized code only for the NH stage; they just use the generic C Poly1305 code for the Poly1305 stage. We can achieve the same result in a simpler way using an (architecture-optimized) nh() function combined with code in crypto/adiantum.c that passes the results to the Poly1305 library. This commit begins this cleanup by adding the nh() function. The code is derived from crypto/nhpoly1305.c and include/crypto/nhpoly1305.h. Link: https://lore.kernel.org/r/20251211011846.8179-2-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org>
52 lines
1.8 KiB
C
52 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* NH hash function for Adiantum
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*/
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#ifndef _CRYPTO_NH_H
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#define _CRYPTO_NH_H
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#include <linux/types.h>
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/* NH parameterization: */
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/* Endianness: little */
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/* Word size: 32 bits (works well on NEON, SSE2, AVX2) */
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/* Stride: 2 words (optimal on ARM32 NEON; works okay on other CPUs too) */
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#define NH_PAIR_STRIDE 2
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#define NH_MESSAGE_UNIT (NH_PAIR_STRIDE * 2 * sizeof(u32))
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/* Num passes (Toeplitz iteration count): 4, to give ε = 2^{-128} */
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#define NH_NUM_PASSES 4
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#define NH_HASH_BYTES (NH_NUM_PASSES * sizeof(u64))
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/* Max message size: 1024 bytes (32x compression factor) */
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#define NH_NUM_STRIDES 64
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#define NH_MESSAGE_WORDS (NH_PAIR_STRIDE * 2 * NH_NUM_STRIDES)
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#define NH_MESSAGE_BYTES (NH_MESSAGE_WORDS * sizeof(u32))
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#define NH_KEY_WORDS (NH_MESSAGE_WORDS + \
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NH_PAIR_STRIDE * 2 * (NH_NUM_PASSES - 1))
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#define NH_KEY_BYTES (NH_KEY_WORDS * sizeof(u32))
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/**
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* nh() - NH hash function for Adiantum
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* @key: The key. @message_len + 48 bytes of it are used. This is NH_KEY_BYTES
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* if @message_len has its maximum length of NH_MESSAGE_BYTES.
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* @message: The message
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* @message_len: The message length in bytes. Must be a multiple of 16
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* (NH_MESSAGE_UNIT) and at most 1024 (NH_MESSAGE_BYTES).
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* @hash: (output) The resulting hash value
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*
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* Note: the pseudocode for NH in the Adiantum paper iterates over 1024-byte
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* segments of the message, computes a 32-byte hash for each, and returns all
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* the hashes concatenated together. In contrast, this function just hashes one
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* segment and returns one hash. It's the caller's responsibility to call this
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* function for each 1024-byte segment and collect all the hashes.
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*
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* Context: Any context.
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*/
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void nh(const u32 *key, const u8 *message, size_t message_len,
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__le64 hash[NH_NUM_PASSES]);
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#endif /* _CRYPTO_NH_H */
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