From 14e15c71d7bb591fd08f527669717694810d3973 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 10 Dec 2025 17:18:33 -0800 Subject: [PATCH] lib/crypto: nh: Add NH library 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 --- include/crypto/nh.h | 52 ++++++++++++++++++++++++++++ lib/crypto/Kconfig | 10 ++++++ lib/crypto/Makefile | 8 +++++ lib/crypto/nh.c | 82 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 152 insertions(+) create mode 100644 include/crypto/nh.h create mode 100644 lib/crypto/nh.c diff --git a/include/crypto/nh.h b/include/crypto/nh.h new file mode 100644 index 0000000000000..465e85bf203f9 --- /dev/null +++ b/include/crypto/nh.h @@ -0,0 +1,52 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * NH hash function for Adiantum + */ + +#ifndef _CRYPTO_NH_H +#define _CRYPTO_NH_H + +#include + +/* NH parameterization: */ + +/* Endianness: little */ +/* Word size: 32 bits (works well on NEON, SSE2, AVX2) */ + +/* Stride: 2 words (optimal on ARM32 NEON; works okay on other CPUs too) */ +#define NH_PAIR_STRIDE 2 +#define NH_MESSAGE_UNIT (NH_PAIR_STRIDE * 2 * sizeof(u32)) + +/* Num passes (Toeplitz iteration count): 4, to give ε = 2^{-128} */ +#define NH_NUM_PASSES 4 +#define NH_HASH_BYTES (NH_NUM_PASSES * sizeof(u64)) + +/* Max message size: 1024 bytes (32x compression factor) */ +#define NH_NUM_STRIDES 64 +#define NH_MESSAGE_WORDS (NH_PAIR_STRIDE * 2 * NH_NUM_STRIDES) +#define NH_MESSAGE_BYTES (NH_MESSAGE_WORDS * sizeof(u32)) +#define NH_KEY_WORDS (NH_MESSAGE_WORDS + \ + NH_PAIR_STRIDE * 2 * (NH_NUM_PASSES - 1)) +#define NH_KEY_BYTES (NH_KEY_WORDS * sizeof(u32)) + +/** + * nh() - NH hash function for Adiantum + * @key: The key. @message_len + 48 bytes of it are used. This is NH_KEY_BYTES + * if @message_len has its maximum length of NH_MESSAGE_BYTES. + * @message: The message + * @message_len: The message length in bytes. Must be a multiple of 16 + * (NH_MESSAGE_UNIT) and at most 1024 (NH_MESSAGE_BYTES). + * @hash: (output) The resulting hash value + * + * Note: the pseudocode for NH in the Adiantum paper iterates over 1024-byte + * segments of the message, computes a 32-byte hash for each, and returns all + * the hashes concatenated together. In contrast, this function just hashes one + * segment and returns one hash. It's the caller's responsibility to call this + * function for each 1024-byte segment and collect all the hashes. + * + * Context: Any context. + */ +void nh(const u32 *key, const u8 *message, size_t message_len, + __le64 hash[NH_NUM_PASSES]); + +#endif /* _CRYPTO_NH_H */ diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig index ee6ab129d0cf6..f14c9f5974d8f 100644 --- a/lib/crypto/Kconfig +++ b/lib/crypto/Kconfig @@ -108,6 +108,16 @@ config CRYPTO_LIB_MLDSA The ML-DSA library functions. Select this if your module uses any of the functions from . +config CRYPTO_LIB_NH + tristate + help + Implementation of the NH almost-universal hash function, specifically + the variant of NH used in Adiantum. + +config CRYPTO_LIB_NH_ARCH + bool + depends on CRYPTO_LIB_NH && !UML + config CRYPTO_LIB_POLY1305 tristate help diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile index a0578105266fc..929b845688096 100644 --- a/lib/crypto/Makefile +++ b/lib/crypto/Makefile @@ -131,6 +131,14 @@ libmldsa-y := mldsa.o ################################################################################ +obj-$(CONFIG_CRYPTO_LIB_NH) += libnh.o +libnh-y := nh.o +ifeq ($(CONFIG_CRYPTO_LIB_NH_ARCH),y) +CFLAGS_nh.o += -I$(src)/$(SRCARCH) +endif + +################################################################################ + obj-$(CONFIG_CRYPTO_LIB_POLY1305) += libpoly1305.o libpoly1305-y := poly1305.o ifeq ($(CONFIG_ARCH_SUPPORTS_INT128),y) diff --git a/lib/crypto/nh.c b/lib/crypto/nh.c new file mode 100644 index 0000000000000..e1d0095b52897 --- /dev/null +++ b/lib/crypto/nh.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2018 Google LLC + */ + +/* + * Implementation of the NH almost-universal hash function, specifically the + * variant of NH used in Adiantum. This is *not* a cryptographic hash function. + * + * Reference: section 6.3 of "Adiantum: length-preserving encryption for + * entry-level processors" (https://eprint.iacr.org/2018/720.pdf). + */ + +#include +#include +#include +#include +#include + +#ifdef CONFIG_CRYPTO_LIB_NH_ARCH +#include "nh.h" /* $(SRCARCH)/nh.h */ +#else +static bool nh_arch(const u32 *key, const u8 *message, size_t message_len, + __le64 hash[NH_NUM_PASSES]) +{ + return false; +} +#endif + +void nh(const u32 *key, const u8 *message, size_t message_len, + __le64 hash[NH_NUM_PASSES]) +{ + u64 sums[4] = { 0, 0, 0, 0 }; + + if (nh_arch(key, message, message_len, hash)) + return; + + static_assert(NH_PAIR_STRIDE == 2); + static_assert(NH_NUM_PASSES == 4); + + while (message_len) { + u32 m0 = get_unaligned_le32(message + 0); + u32 m1 = get_unaligned_le32(message + 4); + u32 m2 = get_unaligned_le32(message + 8); + u32 m3 = get_unaligned_le32(message + 12); + + sums[0] += (u64)(u32)(m0 + key[0]) * (u32)(m2 + key[2]); + sums[1] += (u64)(u32)(m0 + key[4]) * (u32)(m2 + key[6]); + sums[2] += (u64)(u32)(m0 + key[8]) * (u32)(m2 + key[10]); + sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]); + sums[0] += (u64)(u32)(m1 + key[1]) * (u32)(m3 + key[3]); + sums[1] += (u64)(u32)(m1 + key[5]) * (u32)(m3 + key[7]); + sums[2] += (u64)(u32)(m1 + key[9]) * (u32)(m3 + key[11]); + sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]); + key += NH_MESSAGE_UNIT / sizeof(key[0]); + message += NH_MESSAGE_UNIT; + message_len -= NH_MESSAGE_UNIT; + } + + hash[0] = cpu_to_le64(sums[0]); + hash[1] = cpu_to_le64(sums[1]); + hash[2] = cpu_to_le64(sums[2]); + hash[3] = cpu_to_le64(sums[3]); +} +EXPORT_SYMBOL_GPL(nh); + +#ifdef nh_mod_init_arch +static int __init nh_mod_init(void) +{ + nh_mod_init_arch(); + return 0; +} +subsys_initcall(nh_mod_init); + +static void __exit nh_mod_exit(void) +{ +} +module_exit(nh_mod_exit); +#endif + +MODULE_DESCRIPTION("NH almost-universal hash function"); +MODULE_LICENSE("GPL"); -- 2.47.3