/** | |
* \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion | |
* | |
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved | |
* 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. | |
* | |
* This file is part of mbed TLS (https://tls.mbed.org) | |
*/ | |
/* | |
* 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 | |
*/ | |
#if !defined(MBEDTLS_CONFIG_FILE) | |
#include "mbedtls/config.h" | |
#else | |
#include MBEDTLS_CONFIG_FILE | |
#endif | |
#if defined(MBEDTLS_HAVEGE_C) | |
#include "mbedtls/havege.h" | |
#include "mbedtls/timing.h" | |
#include "mbedtls/platform_util.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) { int *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 = (int) 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 = (int) 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 ) | |
{ | |
int i, n = 0; | |
int U1, U2, *A, *B, *C, *D; | |
int PT1, PT2, *WALK, RES[16]; | |
int 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 ) | |
{ | |
int 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(int) ) | |
use_len = sizeof(int); | |
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 */ |