[398] | 1 | /**
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| 2 | * \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion
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| 3 | *
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| 4 | * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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| 5 | * SPDX-License-Identifier: Apache-2.0
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| 6 | *
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| 7 | * Licensed under the Apache License, Version 2.0 (the "License"); you may
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| 8 | * not use this file except in compliance with the License.
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| 9 | * You may obtain a copy of the License at
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| 10 | *
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| 11 | * http://www.apache.org/licenses/LICENSE-2.0
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| 12 | *
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| 13 | * Unless required by applicable law or agreed to in writing, software
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| 14 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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| 15 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 16 | * See the License for the specific language governing permissions and
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| 17 | * limitations under the License.
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| 18 | *
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| 19 | * This file is part of mbed TLS (https://tls.mbed.org)
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| 20 | */
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| 21 | /*
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| 22 | * The HAVEGE RNG was designed by Andre Seznec in 2002.
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| 23 | *
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| 24 | * http://www.irisa.fr/caps/projects/hipsor/publi.php
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| 25 | *
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| 26 | * Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr
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| 27 | */
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| 28 |
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| 29 | #if !defined(MBEDTLS_CONFIG_FILE)
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| 30 | #include "mbedtls/config.h"
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| 31 | #else
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| 32 | #include MBEDTLS_CONFIG_FILE
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| 33 | #endif
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| 34 |
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| 35 | #if defined(MBEDTLS_HAVEGE_C)
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| 36 |
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| 37 | #include "mbedtls/havege.h"
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| 38 | #include "mbedtls/timing.h"
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| 39 | #include "mbedtls/platform_util.h"
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| 40 |
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| 41 | #include <string.h>
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| 42 |
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| 43 | /* ------------------------------------------------------------------------
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| 44 | * On average, one iteration accesses two 8-word blocks in the havege WALK
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| 45 | * table, and generates 16 words in the RES array.
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| 46 | *
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| 47 | * The data read in the WALK table is updated and permuted after each use.
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| 48 | * The result of the hardware clock counter read is used for this update.
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| 49 | *
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| 50 | * 25 conditional tests are present. The conditional tests are grouped in
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| 51 | * two nested groups of 12 conditional tests and 1 test that controls the
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| 52 | * permutation; on average, there should be 6 tests executed and 3 of them
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| 53 | * should be mispredicted.
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| 54 | * ------------------------------------------------------------------------
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| 55 | */
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| 56 |
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| 57 | #define SWAP(X,Y) { int *T = X; X = Y; Y = T; }
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| 58 |
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| 59 | #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
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| 60 | #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
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| 61 |
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| 62 | #define TST1_LEAVE U1++; }
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| 63 | #define TST2_LEAVE U2++; }
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| 64 |
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| 65 | #define ONE_ITERATION \
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| 66 | \
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| 67 | PTEST = PT1 >> 20; \
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| 68 | \
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| 69 | TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
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| 70 | TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
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| 71 | TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
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| 72 | \
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| 73 | TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
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| 74 | TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
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| 75 | TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
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| 76 | \
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| 77 | PTX = (PT1 >> 18) & 7; \
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| 78 | PT1 &= 0x1FFF; \
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| 79 | PT2 &= 0x1FFF; \
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| 80 | CLK = (int) mbedtls_timing_hardclock(); \
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| 81 | \
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| 82 | i = 0; \
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| 83 | A = &WALK[PT1 ]; RES[i++] ^= *A; \
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| 84 | B = &WALK[PT2 ]; RES[i++] ^= *B; \
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| 85 | C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \
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| 86 | D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \
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| 87 | \
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| 88 | IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \
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| 89 | *A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \
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| 90 | *B = IN ^ U1; \
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| 91 | *C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \
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| 92 | *D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \
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| 93 | \
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| 94 | A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \
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| 95 | B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \
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| 96 | C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \
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| 97 | D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \
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| 98 | \
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| 99 | if( PTEST & 1 ) SWAP( A, C ); \
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| 100 | \
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| 101 | IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \
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| 102 | *A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \
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| 103 | *B = IN; CLK = (int) mbedtls_timing_hardclock(); \
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| 104 | *C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \
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| 105 | *D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \
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| 106 | \
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| 107 | A = &WALK[PT1 ^ 4]; \
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| 108 | B = &WALK[PT2 ^ 1]; \
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| 109 | \
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| 110 | PTEST = PT2 >> 1; \
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| 111 | \
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| 112 | PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \
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| 113 | PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \
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| 114 | PTY = (PT2 >> 10) & 7; \
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| 115 | \
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| 116 | TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
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| 117 | TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
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| 118 | TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
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| 119 | \
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| 120 | TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
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| 121 | TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
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| 122 | TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
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| 123 | \
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| 124 | C = &WALK[PT1 ^ 5]; \
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| 125 | D = &WALK[PT2 ^ 5]; \
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| 126 | \
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| 127 | RES[i++] ^= *A; \
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| 128 | RES[i++] ^= *B; \
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| 129 | RES[i++] ^= *C; \
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| 130 | RES[i++] ^= *D; \
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| 131 | \
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| 132 | IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \
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| 133 | *A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \
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| 134 | *B = IN ^ U2; \
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| 135 | *C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \
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| 136 | *D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \
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| 137 | \
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| 138 | A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \
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| 139 | B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \
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| 140 | C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \
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| 141 | D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \
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| 142 | \
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| 143 | IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \
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| 144 | *A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \
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| 145 | *B = IN; \
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| 146 | *C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \
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| 147 | *D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \
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| 148 | \
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| 149 | PT1 = ( RES[( i - 8 ) ^ PTX] ^ \
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| 150 | WALK[PT1 ^ PTX ^ 7] ) & (~1); \
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| 151 | PT1 ^= (PT2 ^ 0x10) & 0x10; \
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| 152 | \
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| 153 | for( n++, i = 0; i < 16; i++ ) \
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| 154 | hs->pool[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i];
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| 155 |
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| 156 | /*
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| 157 | * Entropy gathering function
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| 158 | */
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| 159 | static void havege_fill( mbedtls_havege_state *hs )
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| 160 | {
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| 161 | int i, n = 0;
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| 162 | int U1, U2, *A, *B, *C, *D;
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| 163 | int PT1, PT2, *WALK, RES[16];
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| 164 | int PTX, PTY, CLK, PTEST, IN;
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| 165 |
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| 166 | WALK = hs->WALK;
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| 167 | PT1 = hs->PT1;
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| 168 | PT2 = hs->PT2;
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| 169 |
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| 170 | PTX = U1 = 0;
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| 171 | PTY = U2 = 0;
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| 172 |
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| 173 | (void)PTX;
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| 174 |
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| 175 | memset( RES, 0, sizeof( RES ) );
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| 176 |
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| 177 | while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 )
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| 178 | {
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| 179 | ONE_ITERATION
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| 180 | ONE_ITERATION
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| 181 | ONE_ITERATION
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| 182 | ONE_ITERATION
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| 183 | }
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| 184 |
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| 185 | hs->PT1 = PT1;
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| 186 | hs->PT2 = PT2;
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| 187 |
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| 188 | hs->offset[0] = 0;
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| 189 | hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2;
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| 190 | }
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| 191 |
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| 192 | /*
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| 193 | * HAVEGE initialization
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| 194 | */
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| 195 | void mbedtls_havege_init( mbedtls_havege_state *hs )
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| 196 | {
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| 197 | memset( hs, 0, sizeof( mbedtls_havege_state ) );
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| 198 |
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| 199 | havege_fill( hs );
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| 200 | }
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| 201 |
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| 202 | void mbedtls_havege_free( mbedtls_havege_state *hs )
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| 203 | {
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| 204 | if( hs == NULL )
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| 205 | return;
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| 206 |
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| 207 | mbedtls_platform_zeroize( hs, sizeof( mbedtls_havege_state ) );
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| 208 | }
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| 209 |
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| 210 | /*
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| 211 | * HAVEGE rand function
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| 212 | */
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| 213 | int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len )
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| 214 | {
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| 215 | int val;
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| 216 | size_t use_len;
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| 217 | mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng;
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| 218 | unsigned char *p = buf;
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| 219 |
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| 220 | while( len > 0 )
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| 221 | {
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| 222 | use_len = len;
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| 223 | if( use_len > sizeof(int) )
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| 224 | use_len = sizeof(int);
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| 225 |
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| 226 | if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE )
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| 227 | havege_fill( hs );
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| 228 |
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| 229 | val = hs->pool[hs->offset[0]++];
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| 230 | val ^= hs->pool[hs->offset[1]++];
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| 231 |
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| 232 | memcpy( p, &val, use_len );
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| 233 |
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| 234 | len -= use_len;
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| 235 | p += use_len;
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| 236 | }
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| 237 |
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| 238 | return( 0 );
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| 239 | }
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| 240 |
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| 241 | #endif /* MBEDTLS_HAVEGE_C */
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