1 // SPDX-License-Identifier: Apache-2.0 2 /* 3 * Copyright (c) 2017-2020, Linaro Limited 4 * 5 * NIST SP800-38D compliant GCM implementation 6 * 7 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 8 * 9 * Licensed under the Apache License, Version 2.0 (the "License"); you may 10 * not use this file except in compliance with the License. 11 * You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, software 16 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 17 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 18 * See the License for the specific language governing permissions and 19 * limitations under the License. 20 */ 21 22 #include <crypto/crypto.h> 23 #include <crypto/internal_aes-gcm.h> 24 #include <io.h> 25 #include <string.h> 26 #include <tee_api_types.h> 27 #include <types_ext.h> 28 29 /* 30 * http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf 31 * 32 * See also: 33 * [MGV] http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/ 34 gcm-revised-spec.pdf 35 * 36 * We use the algorithm described as Shoup's method with 4-bit tables in 37 * [MGV] 4.1, pp. 12-13, to enhance speed without using too much memory. 38 */ 39 40 /* 41 * Precompute small multiples of H, that is set 42 * HH[i] || HL[i] = H times i, 43 * where i is seen as a field element as in [MGV], ie high-order bits 44 * correspond to low powers of P. The result is stored in the same way, that 45 * is the high-order bit of HH corresponds to P^0 and the low-order bit of HL 46 * corresponds to P^127. 47 */ 48 void internal_aes_gcm_ghash_gen_tbl(struct internal_ghash_key *ghash_key, 49 const struct internal_aes_gcm_key *ek) 50 { 51 int i, j; 52 uint64_t vl, vh; 53 unsigned char h[16]; 54 55 memset(h, 0, 16); 56 crypto_aes_enc_block(ek->data, sizeof(ek->data), ek->rounds, h, h); 57 58 vh = get_be64(h); 59 vl = get_be64(h + 8); 60 61 /* 8 = 1000 corresponds to 1 in GF(2^128) */ 62 ghash_key->HL[8] = vl; 63 ghash_key->HH[8] = vh; 64 65 /* 0 corresponds to 0 in GF(2^128) */ 66 ghash_key->HH[0] = 0; 67 ghash_key->HL[0] = 0; 68 69 for (i = 4; i > 0; i >>= 1) { 70 uint32_t T = (vl & 1) * 0xe1000000U; 71 72 vl = (vh << 63) | (vl >> 1); 73 vh = (vh >> 1) ^ ((uint64_t)T << 32); 74 75 ghash_key->HL[i] = vl; 76 ghash_key->HH[i] = vh; 77 } 78 79 for (i = 2; i <= 8; i *= 2) { 80 uint64_t *HiL = ghash_key->HL + i; 81 uint64_t *HiH = ghash_key->HH + i; 82 83 vh = *HiH; 84 vl = *HiL; 85 for (j = 1; j < i; j++) { 86 HiH[j] = vh ^ ghash_key->HH[j]; 87 HiL[j] = vl ^ ghash_key->HL[j]; 88 } 89 } 90 } 91 92 /* 93 * Shoup's method for multiplication use this table with 94 * last4[x] = x times P^128 95 * where x and last4[x] are seen as elements of GF(2^128) as in [MGV] 96 */ 97 static const uint64_t last4[16] = { 98 0x0000, 0x1c20, 0x3840, 0x2460, 99 0x7080, 0x6ca0, 0x48c0, 0x54e0, 100 0xe100, 0xfd20, 0xd940, 0xc560, 101 0x9180, 0x8da0, 0xa9c0, 0xb5e0 102 }; 103 104 /* 105 * Sets output to x times H using the precomputed tables. 106 * x and output are seen as elements of GF(2^128) as in [MGV]. 107 */ 108 void internal_aes_gcm_ghash_mult_tbl(struct internal_ghash_key *ghash_key, 109 const unsigned char x[16], 110 unsigned char output[16]) 111 { 112 int i = 0; 113 unsigned char lo = 0, hi = 0, rem = 0; 114 uint64_t zh = 0, zl = 0; 115 116 lo = x[15] & 0xf; 117 118 zh = ghash_key->HH[lo]; 119 zl = ghash_key->HL[lo]; 120 121 for (i = 15; i >= 0; i--) { 122 lo = x[i] & 0xf; 123 hi = x[i] >> 4; 124 125 if (i != 15) { 126 rem = (unsigned char)zl & 0xf; 127 zl = (zh << 60) | (zl >> 4); 128 zh = (zh >> 4); 129 zh ^= (uint64_t)last4[rem] << 48; 130 zh ^= ghash_key->HH[lo]; 131 zl ^= ghash_key->HL[lo]; 132 } 133 134 rem = (unsigned char)zl & 0xf; 135 zl = (zh << 60) | (zl >> 4); 136 zh = (zh >> 4); 137 zh ^= (uint64_t)last4[rem] << 48; 138 zh ^= ghash_key->HH[hi]; 139 zl ^= ghash_key->HL[hi]; 140 } 141 142 put_be64(output, zh); 143 put_be64(output + 8, zl); 144 } 145