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mbedtls/library/havege.c

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/**
* \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion
*
* Copyright (C) 2006-2010, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* 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 "polarssl/config.h"
#if defined(POLARSSL_HAVEGE_C)
#include "polarssl/havege.h"
#include "polarssl/timing.h"
#include <string.h>
#include <time.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) 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) 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 % COLLECT_SIZE] ^= RES[i];
/*
* Entropy gathering function
*/
static void havege_fill( 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;
memset( RES, 0, sizeof( RES ) );
while( n < COLLECT_SIZE * 4 )
{
ONE_ITERATION
ONE_ITERATION
ONE_ITERATION
ONE_ITERATION
}
hs->PT1 = PT1;
hs->PT2 = PT2;
hs->offset[0] = 0;
hs->offset[1] = COLLECT_SIZE / 2;
}
/*
* HAVEGE initialization
*/
void havege_init( havege_state *hs )
{
memset( hs, 0, sizeof( havege_state ) );
havege_fill( hs );
}
/*
* HAVEGE rand function
*/
int havege_random( void *p_rng, unsigned char *buf, size_t len )
{
int val;
size_t use_len;
havege_state *hs = (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] >= 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
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