Mark Radbourne / mbedtls

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Dependents:   Encrypt_Decrypt1 mbed_blink_tls encrypt encrypt

library/havege.c@0:cdf462088d13, 2017-01-05 (annotated)

Committer:
markrad
Date:
Thu Jan 05 00:18:44 2017 +0000
Revision:
0:cdf462088d13
Initial commit

Who changed what in which revision?

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markrad 0:cdf462088d13 1 /**
markrad 0:cdf462088d13 2 * \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion
markrad 0:cdf462088d13 3 *
markrad 0:cdf462088d13 4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
markrad 0:cdf462088d13 5 * SPDX-License-Identifier: Apache-2.0
markrad 0:cdf462088d13 6 *
markrad 0:cdf462088d13 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
markrad 0:cdf462088d13 8 * not use this file except in compliance with the License.
markrad 0:cdf462088d13 9 * You may obtain a copy of the License at
markrad 0:cdf462088d13 10 *
markrad 0:cdf462088d13 11 * http://www.apache.org/licenses/LICENSE-2.0
markrad 0:cdf462088d13 12 *
markrad 0:cdf462088d13 13 * Unless required by applicable law or agreed to in writing, software
markrad 0:cdf462088d13 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
markrad 0:cdf462088d13 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
markrad 0:cdf462088d13 16 * See the License for the specific language governing permissions and
markrad 0:cdf462088d13 17 * limitations under the License.
markrad 0:cdf462088d13 18 *
markrad 0:cdf462088d13 19 * This file is part of mbed TLS (https://tls.mbed.org)
markrad 0:cdf462088d13 20 */
markrad 0:cdf462088d13 21 /*
markrad 0:cdf462088d13 22 * The HAVEGE RNG was designed by Andre Seznec in 2002.
markrad 0:cdf462088d13 23 *
markrad 0:cdf462088d13 24 * http://www.irisa.fr/caps/projects/hipsor/publi.php
markrad 0:cdf462088d13 25 *
markrad 0:cdf462088d13 26 * Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr
markrad 0:cdf462088d13 27 */
markrad 0:cdf462088d13 28
markrad 0:cdf462088d13 29 #if !defined(MBEDTLS_CONFIG_FILE)
markrad 0:cdf462088d13 30 #include "mbedtls/config.h"
markrad 0:cdf462088d13 31 #else
markrad 0:cdf462088d13 32 #include MBEDTLS_CONFIG_FILE
markrad 0:cdf462088d13 33 #endif
markrad 0:cdf462088d13 34
markrad 0:cdf462088d13 35 #if defined(MBEDTLS_HAVEGE_C)
markrad 0:cdf462088d13 36
markrad 0:cdf462088d13 37 #include "mbedtls/havege.h"
markrad 0:cdf462088d13 38 #include "mbedtls/timing.h"
markrad 0:cdf462088d13 39
markrad 0:cdf462088d13 40 #include <string.h>
markrad 0:cdf462088d13 41
markrad 0:cdf462088d13 42 /* Implementation that should never be optimized out by the compiler */
markrad 0:cdf462088d13 43 static void mbedtls_zeroize( void *v, size_t n ) {
markrad 0:cdf462088d13 44 volatile unsigned char *p = v; while( n-- ) *p++ = 0;
markrad 0:cdf462088d13 45 }
markrad 0:cdf462088d13 46
markrad 0:cdf462088d13 47 /* ------------------------------------------------------------------------
markrad 0:cdf462088d13 48 * On average, one iteration accesses two 8-word blocks in the havege WALK
markrad 0:cdf462088d13 49 * table, and generates 16 words in the RES array.
markrad 0:cdf462088d13 50 *
markrad 0:cdf462088d13 51 * The data read in the WALK table is updated and permuted after each use.
markrad 0:cdf462088d13 52 * The result of the hardware clock counter read is used for this update.
markrad 0:cdf462088d13 53 *
markrad 0:cdf462088d13 54 * 25 conditional tests are present. The conditional tests are grouped in
markrad 0:cdf462088d13 55 * two nested groups of 12 conditional tests and 1 test that controls the
markrad 0:cdf462088d13 56 * permutation; on average, there should be 6 tests executed and 3 of them
markrad 0:cdf462088d13 57 * should be mispredicted.
markrad 0:cdf462088d13 58 * ------------------------------------------------------------------------
markrad 0:cdf462088d13 59 */
markrad 0:cdf462088d13 60
markrad 0:cdf462088d13 61 #define SWAP(X,Y) { int *T = X; X = Y; Y = T; }
markrad 0:cdf462088d13 62
markrad 0:cdf462088d13 63 #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
markrad 0:cdf462088d13 64 #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
markrad 0:cdf462088d13 65
markrad 0:cdf462088d13 66 #define TST1_LEAVE U1++; }
markrad 0:cdf462088d13 67 #define TST2_LEAVE U2++; }
markrad 0:cdf462088d13 68
markrad 0:cdf462088d13 69 #define ONE_ITERATION \
markrad 0:cdf462088d13 70 \
markrad 0:cdf462088d13 71 PTEST = PT1 >> 20; \
markrad 0:cdf462088d13 72 \
markrad 0:cdf462088d13 73 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
markrad 0:cdf462088d13 74 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
markrad 0:cdf462088d13 75 TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
markrad 0:cdf462088d13 76 \
markrad 0:cdf462088d13 77 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
markrad 0:cdf462088d13 78 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
markrad 0:cdf462088d13 79 TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
markrad 0:cdf462088d13 80 \
markrad 0:cdf462088d13 81 PTX = (PT1 >> 18) & 7; \
markrad 0:cdf462088d13 82 PT1 &= 0x1FFF; \
markrad 0:cdf462088d13 83 PT2 &= 0x1FFF; \
markrad 0:cdf462088d13 84 CLK = (int) mbedtls_timing_hardclock(); \
markrad 0:cdf462088d13 85 \
markrad 0:cdf462088d13 86 i = 0; \
markrad 0:cdf462088d13 87 A = &WALK[PT1 ]; RES[i++] ^= *A; \
markrad 0:cdf462088d13 88 B = &WALK[PT2 ]; RES[i++] ^= *B; \
markrad 0:cdf462088d13 89 C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \
markrad 0:cdf462088d13 90 D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \
markrad 0:cdf462088d13 91 \
markrad 0:cdf462088d13 92 IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \
markrad 0:cdf462088d13 93 *A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \
markrad 0:cdf462088d13 94 *B = IN ^ U1; \
markrad 0:cdf462088d13 95 *C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \
markrad 0:cdf462088d13 96 *D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \
markrad 0:cdf462088d13 97 \
markrad 0:cdf462088d13 98 A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \
markrad 0:cdf462088d13 99 B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \
markrad 0:cdf462088d13 100 C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \
markrad 0:cdf462088d13 101 D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \
markrad 0:cdf462088d13 102 \
markrad 0:cdf462088d13 103 if( PTEST & 1 ) SWAP( A, C ); \
markrad 0:cdf462088d13 104 \
markrad 0:cdf462088d13 105 IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \
markrad 0:cdf462088d13 106 *A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \
markrad 0:cdf462088d13 107 *B = IN; CLK = (int) mbedtls_timing_hardclock(); \
markrad 0:cdf462088d13 108 *C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \
markrad 0:cdf462088d13 109 *D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \
markrad 0:cdf462088d13 110 \
markrad 0:cdf462088d13 111 A = &WALK[PT1 ^ 4]; \
markrad 0:cdf462088d13 112 B = &WALK[PT2 ^ 1]; \
markrad 0:cdf462088d13 113 \
markrad 0:cdf462088d13 114 PTEST = PT2 >> 1; \
markrad 0:cdf462088d13 115 \
markrad 0:cdf462088d13 116 PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \
markrad 0:cdf462088d13 117 PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \
markrad 0:cdf462088d13 118 PTY = (PT2 >> 10) & 7; \
markrad 0:cdf462088d13 119 \
markrad 0:cdf462088d13 120 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
markrad 0:cdf462088d13 121 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
markrad 0:cdf462088d13 122 TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
markrad 0:cdf462088d13 123 \
markrad 0:cdf462088d13 124 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
markrad 0:cdf462088d13 125 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
markrad 0:cdf462088d13 126 TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
markrad 0:cdf462088d13 127 \
markrad 0:cdf462088d13 128 C = &WALK[PT1 ^ 5]; \
markrad 0:cdf462088d13 129 D = &WALK[PT2 ^ 5]; \
markrad 0:cdf462088d13 130 \
markrad 0:cdf462088d13 131 RES[i++] ^= *A; \
markrad 0:cdf462088d13 132 RES[i++] ^= *B; \
markrad 0:cdf462088d13 133 RES[i++] ^= *C; \
markrad 0:cdf462088d13 134 RES[i++] ^= *D; \
markrad 0:cdf462088d13 135 \
markrad 0:cdf462088d13 136 IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \
markrad 0:cdf462088d13 137 *A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \
markrad 0:cdf462088d13 138 *B = IN ^ U2; \
markrad 0:cdf462088d13 139 *C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \
markrad 0:cdf462088d13 140 *D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \
markrad 0:cdf462088d13 141 \
markrad 0:cdf462088d13 142 A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \
markrad 0:cdf462088d13 143 B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \
markrad 0:cdf462088d13 144 C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \
markrad 0:cdf462088d13 145 D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \
markrad 0:cdf462088d13 146 \
markrad 0:cdf462088d13 147 IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \
markrad 0:cdf462088d13 148 *A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \
markrad 0:cdf462088d13 149 *B = IN; \
markrad 0:cdf462088d13 150 *C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \
markrad 0:cdf462088d13 151 *D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \
markrad 0:cdf462088d13 152 \
markrad 0:cdf462088d13 153 PT1 = ( RES[( i - 8 ) ^ PTX] ^ \
markrad 0:cdf462088d13 154 WALK[PT1 ^ PTX ^ 7] ) & (~1); \
markrad 0:cdf462088d13 155 PT1 ^= (PT2 ^ 0x10) & 0x10; \
markrad 0:cdf462088d13 156 \
markrad 0:cdf462088d13 157 for( n++, i = 0; i < 16; i++ ) \
markrad 0:cdf462088d13 158 hs->pool[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i];
markrad 0:cdf462088d13 159
markrad 0:cdf462088d13 160 /*
markrad 0:cdf462088d13 161 * Entropy gathering function
markrad 0:cdf462088d13 162 */
markrad 0:cdf462088d13 163 static void havege_fill( mbedtls_havege_state *hs )
markrad 0:cdf462088d13 164 {
markrad 0:cdf462088d13 165 int i, n = 0;
markrad 0:cdf462088d13 166 int U1, U2, *A, *B, *C, *D;
markrad 0:cdf462088d13 167 int PT1, PT2, *WALK, RES[16];
markrad 0:cdf462088d13 168 int PTX, PTY, CLK, PTEST, IN;
markrad 0:cdf462088d13 169
markrad 0:cdf462088d13 170 WALK = hs->WALK;
markrad 0:cdf462088d13 171 PT1 = hs->PT1;
markrad 0:cdf462088d13 172 PT2 = hs->PT2;
markrad 0:cdf462088d13 173
markrad 0:cdf462088d13 174 PTX = U1 = 0;
markrad 0:cdf462088d13 175 PTY = U2 = 0;
markrad 0:cdf462088d13 176
markrad 0:cdf462088d13 177 (void)PTX;
markrad 0:cdf462088d13 178
markrad 0:cdf462088d13 179 memset( RES, 0, sizeof( RES ) );
markrad 0:cdf462088d13 180
markrad 0:cdf462088d13 181 while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 )
markrad 0:cdf462088d13 182 {
markrad 0:cdf462088d13 183 ONE_ITERATION
markrad 0:cdf462088d13 184 ONE_ITERATION
markrad 0:cdf462088d13 185 ONE_ITERATION
markrad 0:cdf462088d13 186 ONE_ITERATION
markrad 0:cdf462088d13 187 }
markrad 0:cdf462088d13 188
markrad 0:cdf462088d13 189 hs->PT1 = PT1;
markrad 0:cdf462088d13 190 hs->PT2 = PT2;
markrad 0:cdf462088d13 191
markrad 0:cdf462088d13 192 hs->offset[0] = 0;
markrad 0:cdf462088d13 193 hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2;
markrad 0:cdf462088d13 194 }
markrad 0:cdf462088d13 195
markrad 0:cdf462088d13 196 /*
markrad 0:cdf462088d13 197 * HAVEGE initialization
markrad 0:cdf462088d13 198 */
markrad 0:cdf462088d13 199 void mbedtls_havege_init( mbedtls_havege_state *hs )
markrad 0:cdf462088d13 200 {
markrad 0:cdf462088d13 201 memset( hs, 0, sizeof( mbedtls_havege_state ) );
markrad 0:cdf462088d13 202
markrad 0:cdf462088d13 203 havege_fill( hs );
markrad 0:cdf462088d13 204 }
markrad 0:cdf462088d13 205
markrad 0:cdf462088d13 206 void mbedtls_havege_free( mbedtls_havege_state *hs )
markrad 0:cdf462088d13 207 {
markrad 0:cdf462088d13 208 if( hs == NULL )
markrad 0:cdf462088d13 209 return;
markrad 0:cdf462088d13 210
markrad 0:cdf462088d13 211 mbedtls_zeroize( hs, sizeof( mbedtls_havege_state ) );
markrad 0:cdf462088d13 212 }
markrad 0:cdf462088d13 213
markrad 0:cdf462088d13 214 /*
markrad 0:cdf462088d13 215 * HAVEGE rand function
markrad 0:cdf462088d13 216 */
markrad 0:cdf462088d13 217 int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len )
markrad 0:cdf462088d13 218 {
markrad 0:cdf462088d13 219 int val;
markrad 0:cdf462088d13 220 size_t use_len;
markrad 0:cdf462088d13 221 mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng;
markrad 0:cdf462088d13 222 unsigned char *p = buf;
markrad 0:cdf462088d13 223
markrad 0:cdf462088d13 224 while( len > 0 )
markrad 0:cdf462088d13 225 {
markrad 0:cdf462088d13 226 use_len = len;
markrad 0:cdf462088d13 227 if( use_len > sizeof(int) )
markrad 0:cdf462088d13 228 use_len = sizeof(int);
markrad 0:cdf462088d13 229
markrad 0:cdf462088d13 230 if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE )
markrad 0:cdf462088d13 231 havege_fill( hs );
markrad 0:cdf462088d13 232
markrad 0:cdf462088d13 233 val = hs->pool[hs->offset[0]++];
markrad 0:cdf462088d13 234 val ^= hs->pool[hs->offset[1]++];
markrad 0:cdf462088d13 235
markrad 0:cdf462088d13 236 memcpy( p, &val, use_len );
markrad 0:cdf462088d13 237
markrad 0:cdf462088d13 238 len -= use_len;
markrad 0:cdf462088d13 239 p += use_len;
markrad 0:cdf462088d13 240 }
markrad 0:cdf462088d13 241
markrad 0:cdf462088d13 242 return( 0 );
markrad 0:cdf462088d13 243 }
markrad 0:cdf462088d13 244
markrad 0:cdf462088d13 245 #endif /* MBEDTLS_HAVEGE_C */