1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright 2018 Google LLC 4 */ 5 6 /* 7 * Implementation of the NH almost-universal hash function, specifically the 8 * variant of NH used in Adiantum. This is *not* a cryptographic hash function. 9 * 10 * Reference: section 6.3 of "Adiantum: length-preserving encryption for 11 * entry-level processors" (https://eprint.iacr.org/2018/720.pdf). 12 */ 13 14 #include <crypto/nh.h> 15 #include <linux/export.h> 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/unaligned.h> 19 20 #ifdef CONFIG_CRYPTO_LIB_NH_ARCH 21 #include "nh.h" /* $(SRCARCH)/nh.h */ 22 #else 23 static bool nh_arch(const u32 *key, const u8 *message, size_t message_len, 24 __le64 hash[NH_NUM_PASSES]) 25 { 26 return false; 27 } 28 #endif 29 30 void nh(const u32 *key, const u8 *message, size_t message_len, 31 __le64 hash[NH_NUM_PASSES]) 32 { 33 u64 sums[4] = { 0, 0, 0, 0 }; 34 35 if (nh_arch(key, message, message_len, hash)) 36 return; 37 38 static_assert(NH_PAIR_STRIDE == 2); 39 static_assert(NH_NUM_PASSES == 4); 40 41 while (message_len) { 42 u32 m0 = get_unaligned_le32(message + 0); 43 u32 m1 = get_unaligned_le32(message + 4); 44 u32 m2 = get_unaligned_le32(message + 8); 45 u32 m3 = get_unaligned_le32(message + 12); 46 47 sums[0] += (u64)(u32)(m0 + key[0]) * (u32)(m2 + key[2]); 48 sums[1] += (u64)(u32)(m0 + key[4]) * (u32)(m2 + key[6]); 49 sums[2] += (u64)(u32)(m0 + key[8]) * (u32)(m2 + key[10]); 50 sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]); 51 sums[0] += (u64)(u32)(m1 + key[1]) * (u32)(m3 + key[3]); 52 sums[1] += (u64)(u32)(m1 + key[5]) * (u32)(m3 + key[7]); 53 sums[2] += (u64)(u32)(m1 + key[9]) * (u32)(m3 + key[11]); 54 sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]); 55 key += NH_MESSAGE_UNIT / sizeof(key[0]); 56 message += NH_MESSAGE_UNIT; 57 message_len -= NH_MESSAGE_UNIT; 58 } 59 60 hash[0] = cpu_to_le64(sums[0]); 61 hash[1] = cpu_to_le64(sums[1]); 62 hash[2] = cpu_to_le64(sums[2]); 63 hash[3] = cpu_to_le64(sums[3]); 64 } 65 EXPORT_SYMBOL_GPL(nh); 66 67 #ifdef nh_mod_init_arch 68 static int __init nh_mod_init(void) 69 { 70 nh_mod_init_arch(); 71 return 0; 72 } 73 subsys_initcall(nh_mod_init); 74 75 static void __exit nh_mod_exit(void) 76 { 77 } 78 module_exit(nh_mod_exit); 79 #endif 80 81 MODULE_DESCRIPTION("NH almost-universal hash function"); 82 MODULE_LICENSE("GPL"); 83