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// 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 <crypto/nh.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/unaligned.h>
#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");
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