| /** |
| * \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion |
| * |
| * Copyright The Mbed TLS Contributors |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| /* |
| * The HAVEGE RNG was designed by Andre Seznec in 2002. |
| * |
| * http://www.irisa.fr/caps/projects/hipsor/publi.php |
| * |
| * Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr |
| */ |
| |
| #include "common.h" |
| |
| #if defined(MBEDTLS_HAVEGE_C) |
| |
| #include "mbedtls/havege.h" |
| #include "mbedtls/timing.h" |
| #include "mbedtls/platform_util.h" |
| |
| #include <stdint.h> |
| #include <string.h> |
| |
| /* ------------------------------------------------------------------------ |
| * On average, one iteration accesses two 8-word blocks in the havege WALK |
| * table, and generates 16 words in the RES array. |
| * |
| * The data read in the WALK table is updated and permuted after each use. |
| * The result of the hardware clock counter read is used for this update. |
| * |
| * 25 conditional tests are present. The conditional tests are grouped in |
| * two nested groups of 12 conditional tests and 1 test that controls the |
| * permutation; on average, there should be 6 tests executed and 3 of them |
| * should be mispredicted. |
| * ------------------------------------------------------------------------ |
| */ |
| |
| #define SWAP(X,Y) { uint32_t *T = (X); (X) = (Y); (Y) = T; } |
| |
| #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; |
| #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1; |
| |
| #define TST1_LEAVE U1++; } |
| #define TST2_LEAVE U2++; } |
| |
| #define ONE_ITERATION \ |
| \ |
| PTEST = PT1 >> 20; \ |
| \ |
| TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ |
| TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ |
| TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \ |
| \ |
| TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ |
| TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ |
| TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \ |
| \ |
| PTX = (PT1 >> 18) & 7; \ |
| PT1 &= 0x1FFF; \ |
| PT2 &= 0x1FFF; \ |
| CLK = (uint32_t) mbedtls_timing_hardclock(); \ |
| \ |
| i = 0; \ |
| A = &WALK[PT1 ]; RES[i++] ^= *A; \ |
| B = &WALK[PT2 ]; RES[i++] ^= *B; \ |
| C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \ |
| D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \ |
| \ |
| IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \ |
| *A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \ |
| *B = IN ^ U1; \ |
| *C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \ |
| *D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \ |
| \ |
| A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \ |
| B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \ |
| C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \ |
| D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \ |
| \ |
| if( PTEST & 1 ) SWAP( A, C ); \ |
| \ |
| IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \ |
| *A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \ |
| *B = IN; CLK = (uint32_t) mbedtls_timing_hardclock(); \ |
| *C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \ |
| *D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \ |
| \ |
| A = &WALK[PT1 ^ 4]; \ |
| B = &WALK[PT2 ^ 1]; \ |
| \ |
| PTEST = PT2 >> 1; \ |
| \ |
| PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \ |
| PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \ |
| PTY = (PT2 >> 10) & 7; \ |
| \ |
| TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ |
| TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ |
| TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \ |
| \ |
| TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ |
| TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ |
| TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \ |
| \ |
| C = &WALK[PT1 ^ 5]; \ |
| D = &WALK[PT2 ^ 5]; \ |
| \ |
| RES[i++] ^= *A; \ |
| RES[i++] ^= *B; \ |
| RES[i++] ^= *C; \ |
| RES[i++] ^= *D; \ |
| \ |
| IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \ |
| *A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \ |
| *B = IN ^ U2; \ |
| *C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \ |
| *D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \ |
| \ |
| A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \ |
| B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \ |
| C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \ |
| D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \ |
| \ |
| IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \ |
| *A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \ |
| *B = IN; \ |
| *C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \ |
| *D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \ |
| \ |
| PT1 = ( RES[( i - 8 ) ^ PTX] ^ \ |
| WALK[PT1 ^ PTX ^ 7] ) & (~1); \ |
| PT1 ^= (PT2 ^ 0x10) & 0x10; \ |
| \ |
| for( n++, i = 0; i < 16; i++ ) \ |
| hs->pool[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i]; |
| |
| /* |
| * Entropy gathering function |
| */ |
| static void havege_fill( mbedtls_havege_state *hs ) |
| { |
| size_t n = 0; |
| size_t i; |
| uint32_t U1, U2, *A, *B, *C, *D; |
| uint32_t PT1, PT2, *WALK, RES[16]; |
| uint32_t PTX, PTY, CLK, PTEST, IN; |
| |
| WALK = hs->WALK; |
| PT1 = hs->PT1; |
| PT2 = hs->PT2; |
| |
| PTX = U1 = 0; |
| PTY = U2 = 0; |
| |
| (void)PTX; |
| |
| memset( RES, 0, sizeof( RES ) ); |
| |
| while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 ) |
| { |
| ONE_ITERATION |
| ONE_ITERATION |
| ONE_ITERATION |
| ONE_ITERATION |
| } |
| |
| hs->PT1 = PT1; |
| hs->PT2 = PT2; |
| |
| hs->offset[0] = 0; |
| hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2; |
| } |
| |
| /* |
| * HAVEGE initialization |
| */ |
| void mbedtls_havege_init( mbedtls_havege_state *hs ) |
| { |
| memset( hs, 0, sizeof( mbedtls_havege_state ) ); |
| |
| havege_fill( hs ); |
| } |
| |
| void mbedtls_havege_free( mbedtls_havege_state *hs ) |
| { |
| if( hs == NULL ) |
| return; |
| |
| mbedtls_platform_zeroize( hs, sizeof( mbedtls_havege_state ) ); |
| } |
| |
| /* |
| * HAVEGE rand function |
| */ |
| int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len ) |
| { |
| uint32_t val; |
| size_t use_len; |
| mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng; |
| unsigned char *p = buf; |
| |
| while( len > 0 ) |
| { |
| use_len = len; |
| if( use_len > sizeof( val ) ) |
| use_len = sizeof( val ); |
| |
| if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE ) |
| havege_fill( hs ); |
| |
| val = hs->pool[hs->offset[0]++]; |
| val ^= hs->pool[hs->offset[1]++]; |
| |
| memcpy( p, &val, use_len ); |
| |
| len -= use_len; |
| p += use_len; |
| } |
| |
| return( 0 ); |
| } |
| |
| #endif /* MBEDTLS_HAVEGE_C */ |
