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| 3 | * Copyright 2018 Google LLC
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| 4 |
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| 5 |
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| 6 | |
| 7 | * Implementation of the NH almost-universal hash function, specifically the
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| 8 | * variant of NH used in Adiantum. This is *not* a cryptographic hash function.
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| 9 | *
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| 10 | * Reference: section 6.3 of "Adiantum: length-preserving encryption for
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| 11 | * entry-level processors" (https://eprint.iacr.org/2018/720.pdf).
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| 12 |
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| 13 |
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| 14 | #include <crypto/nh.h>
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| 15 | #include <linux/export.h>
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| 16 | #include <linux/kernel.h>
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| 17 | #include <linux/module.h>
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| 18 | #include <linux/unaligned.h>
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| 19 |
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| 20 | #ifdef CONFIG_CRYPTO_LIB_NH_ARCH
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| 21 | #include "nh.h"
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| 22 | #else
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| 23 | static bool nh_arch(const u32 *key, const u8 *message, size_t message_len,
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| 24 | __le64 hash[NH_NUM_PASSES])
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| 25 | {
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| 26 | return false;
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| 27 | }
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| 28 | #endif
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| 29 |
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| 30 | void nh(const u32 *key, const u8 *message, size_t message_len,
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| 31 | __le64 hash[NH_NUM_PASSES])
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| 32 | {
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| 33 | u64 sums[4] = { 0, 0, 0, 0 };
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| 34 |
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| 35 | if (nh_arch(key, message, message_len, hash))
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| 36 | return;
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| 37 |
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| 38 | static_assert(NH_PAIR_STRIDE == 2);
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| 39 | static_assert(NH_NUM_PASSES == 4);
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| 40 |
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| 41 | while (message_len) {
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| 42 | u32 m0 = get_unaligned_le32(message + 0);
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| 43 | u32 m1 = get_unaligned_le32(message + 4);
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| 44 | u32 m2 = get_unaligned_le32(message + 8);
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| 45 | u32 m3 = get_unaligned_le32(message + 12);
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| 46 |
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| 47 | sums[0] += (u64)(u32)(m0 + key[0]) * (u32)(m2 + key[2]);
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| 48 | sums[1] += (u64)(u32)(m0 + key[4]) * (u32)(m2 + key[6]);
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| 49 | sums[2] += (u64)(u32)(m0 + key[8]) * (u32)(m2 + key[10]);
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| 50 | sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
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| 51 | sums[0] += (u64)(u32)(m1 + key[1]) * (u32)(m3 + key[3]);
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| 52 | sums[1] += (u64)(u32)(m1 + key[5]) * (u32)(m3 + key[7]);
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| 53 | sums[2] += (u64)(u32)(m1 + key[9]) * (u32)(m3 + key[11]);
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| 54 | sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
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| 55 | key += NH_MESSAGE_UNIT / sizeof(key[0]);
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| 56 | message += NH_MESSAGE_UNIT;
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| 57 | message_len -= NH_MESSAGE_UNIT;
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| 58 | }
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| 59 |
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| 60 | hash[0] = cpu_to_le64(sums[0]);
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| 61 | hash[1] = cpu_to_le64(sums[1]);
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| 62 | hash[2] = cpu_to_le64(sums[2]);
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| 63 | hash[3] = cpu_to_le64(sums[3]);
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| 64 | }
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| 65 | EXPORT_SYMBOL_GPL(nh);
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| 66 |
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| 67 | #ifdef nh_mod_init_arch
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| 68 | static int __init nh_mod_init(void)
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| 69 | {
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| 70 | nh_mod_init_arch();
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| 71 | return 0;
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| 72 | }
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| 73 | subsys_initcall(nh_mod_init);
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| 74 |
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| 75 | static void __exit nh_mod_exit(void)
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| 76 | {
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| 77 | }
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| 78 | module_exit(nh_mod_exit);
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| 79 | #endif
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| 80 |
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| 81 | MODULE_DESCRIPTION("NH almost-universal hash function");
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| 82 | MODULE_LICENSE("GPL");
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