Marco Zecchini
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Example_RTOS
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havege.c
00001 /** 00002 * \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion 00003 * 00004 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 00005 * SPDX-License-Identifier: Apache-2.0 00006 * 00007 * Licensed under the Apache License, Version 2.0 (the "License"); you may 00008 * not use this file except in compliance with the License. 00009 * You may obtain a copy of the License at 00010 * 00011 * http://www.apache.org/licenses/LICENSE-2.0 00012 * 00013 * Unless required by applicable law or agreed to in writing, software 00014 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 00015 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00016 * See the License for the specific language governing permissions and 00017 * limitations under the License. 00018 * 00019 * This file is part of mbed TLS (https://tls.mbed.org) 00020 */ 00021 /* 00022 * The HAVEGE RNG was designed by Andre Seznec in 2002. 00023 * 00024 * http://www.irisa.fr/caps/projects/hipsor/publi.php 00025 * 00026 * Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr 00027 */ 00028 00029 #if !defined(MBEDTLS_CONFIG_FILE) 00030 #include "mbedtls/config.h" 00031 #else 00032 #include MBEDTLS_CONFIG_FILE 00033 #endif 00034 00035 #if defined(MBEDTLS_HAVEGE_C) 00036 00037 #include "mbedtls/havege.h" 00038 #include "mbedtls/timing.h" 00039 00040 #include <string.h> 00041 00042 /* Implementation that should never be optimized out by the compiler */ 00043 static void mbedtls_zeroize( void *v, size_t n ) { 00044 volatile unsigned char *p = v; while( n-- ) *p++ = 0; 00045 } 00046 00047 /* ------------------------------------------------------------------------ 00048 * On average, one iteration accesses two 8-word blocks in the havege WALK 00049 * table, and generates 16 words in the RES array. 00050 * 00051 * The data read in the WALK table is updated and permuted after each use. 00052 * The result of the hardware clock counter read is used for this update. 00053 * 00054 * 25 conditional tests are present. The conditional tests are grouped in 00055 * two nested groups of 12 conditional tests and 1 test that controls the 00056 * permutation; on average, there should be 6 tests executed and 3 of them 00057 * should be mispredicted. 00058 * ------------------------------------------------------------------------ 00059 */ 00060 00061 #define SWAP(X,Y) { int *T = X; X = Y; Y = T; } 00062 00063 #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; 00064 #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; 00065 00066 #define TST1_LEAVE U1++; } 00067 #define TST2_LEAVE U2++; } 00068 00069 #define ONE_ITERATION \ 00070 \ 00071 PTEST = PT1 >> 20; \ 00072 \ 00073 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 00074 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 00075 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ 00076 \ 00077 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 00078 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 00079 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ 00080 \ 00081 PTX = (PT1 >> 18) & 7; \ 00082 PT1 &= 0x1FFF; \ 00083 PT2 &= 0x1FFF; \ 00084 CLK = (int) mbedtls_timing_hardclock(); \ 00085 \ 00086 i = 0; \ 00087 A = &WALK[PT1 ]; RES[i++] ^= *A; \ 00088 B = &WALK[PT2 ]; RES[i++] ^= *B; \ 00089 C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \ 00090 D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \ 00091 \ 00092 IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \ 00093 *A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \ 00094 *B = IN ^ U1; \ 00095 *C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \ 00096 *D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \ 00097 \ 00098 A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \ 00099 B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \ 00100 C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \ 00101 D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \ 00102 \ 00103 if( PTEST & 1 ) SWAP( A, C ); \ 00104 \ 00105 IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \ 00106 *A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \ 00107 *B = IN; CLK = (int) mbedtls_timing_hardclock(); \ 00108 *C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \ 00109 *D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \ 00110 \ 00111 A = &WALK[PT1 ^ 4]; \ 00112 B = &WALK[PT2 ^ 1]; \ 00113 \ 00114 PTEST = PT2 >> 1; \ 00115 \ 00116 PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \ 00117 PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \ 00118 PTY = (PT2 >> 10) & 7; \ 00119 \ 00120 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 00121 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 00122 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ 00123 \ 00124 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 00125 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 00126 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ 00127 \ 00128 C = &WALK[PT1 ^ 5]; \ 00129 D = &WALK[PT2 ^ 5]; \ 00130 \ 00131 RES[i++] ^= *A; \ 00132 RES[i++] ^= *B; \ 00133 RES[i++] ^= *C; \ 00134 RES[i++] ^= *D; \ 00135 \ 00136 IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \ 00137 *A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \ 00138 *B = IN ^ U2; \ 00139 *C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \ 00140 *D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \ 00141 \ 00142 A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \ 00143 B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \ 00144 C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \ 00145 D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \ 00146 \ 00147 IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \ 00148 *A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \ 00149 *B = IN; \ 00150 *C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \ 00151 *D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \ 00152 \ 00153 PT1 = ( RES[( i - 8 ) ^ PTX] ^ \ 00154 WALK[PT1 ^ PTX ^ 7] ) & (~1); \ 00155 PT1 ^= (PT2 ^ 0x10) & 0x10; \ 00156 \ 00157 for( n++, i = 0; i < 16; i++ ) \ 00158 hs->pool[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i]; 00159 00160 /* 00161 * Entropy gathering function 00162 */ 00163 static void havege_fill( mbedtls_havege_state *hs ) 00164 { 00165 int i, n = 0; 00166 int U1, U2, *A, *B, *C, *D; 00167 int PT1, PT2, *WALK, RES[16]; 00168 int PTX, PTY, CLK, PTEST, IN; 00169 00170 WALK = hs->WALK; 00171 PT1 = hs->PT1; 00172 PT2 = hs->PT2; 00173 00174 PTX = U1 = 0; 00175 PTY = U2 = 0; 00176 00177 (void)PTX; 00178 00179 memset( RES, 0, sizeof( RES ) ); 00180 00181 while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 ) 00182 { 00183 ONE_ITERATION 00184 ONE_ITERATION 00185 ONE_ITERATION 00186 ONE_ITERATION 00187 } 00188 00189 hs->PT1 = PT1; 00190 hs->PT2 = PT2; 00191 00192 hs->offset[0] = 0; 00193 hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2; 00194 } 00195 00196 /* 00197 * HAVEGE initialization 00198 */ 00199 void mbedtls_havege_init( mbedtls_havege_state *hs ) 00200 { 00201 memset( hs, 0, sizeof( mbedtls_havege_state ) ); 00202 00203 havege_fill( hs ); 00204 } 00205 00206 void mbedtls_havege_free( mbedtls_havege_state *hs ) 00207 { 00208 if( hs == NULL ) 00209 return; 00210 00211 mbedtls_zeroize( hs, sizeof( mbedtls_havege_state ) ); 00212 } 00213 00214 /* 00215 * HAVEGE rand function 00216 */ 00217 int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len ) 00218 { 00219 int val; 00220 size_t use_len; 00221 mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng; 00222 unsigned char *p = buf; 00223 00224 while( len > 0 ) 00225 { 00226 use_len = len; 00227 if( use_len > sizeof(int) ) 00228 use_len = sizeof(int); 00229 00230 if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE ) 00231 havege_fill( hs ); 00232 00233 val = hs->pool[hs->offset[0]++]; 00234 val ^= hs->pool[hs->offset[1]++]; 00235 00236 memcpy( p, &val, use_len ); 00237 00238 len -= use_len; 00239 p += use_len; 00240 } 00241 00242 return( 0 ); 00243 } 00244 00245 #endif /* MBEDTLS_HAVEGE_C */
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