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246 lines
9 KiB
C
246 lines
9 KiB
C
/**
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* \brief HAVEGE: HArdware Volatile Entropy Gathering and Expansion
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*
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* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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/*
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* The HAVEGE RNG was designed by Andre Seznec in 2002.
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*
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* http://www.irisa.fr/caps/projects/hipsor/publi.php
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*
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* Contact: seznec(at)irisa_dot_fr - orocheco(at)irisa_dot_fr
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_HAVEGE_C)
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#include "mbedtls/havege.h"
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#include "mbedtls/timing.h"
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#include <string.h>
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/* Implementation that should never be optimized out by the compiler */
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static void mbedtls_zeroize( void *v, size_t n ) {
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volatile unsigned char *p = v; while( n-- ) *p++ = 0;
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}
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/* ------------------------------------------------------------------------
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* On average, one iteration accesses two 8-word blocks in the havege WALK
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* table, and generates 16 words in the RES array.
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*
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* The data read in the WALK table is updated and permuted after each use.
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* The result of the hardware clock counter read is used for this update.
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*
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* 25 conditional tests are present. The conditional tests are grouped in
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* two nested groups of 12 conditional tests and 1 test that controls the
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* permutation; on average, there should be 6 tests executed and 3 of them
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* should be mispredicted.
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* ------------------------------------------------------------------------
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*/
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#define SWAP(X,Y) { int *T = X; X = Y; Y = T; }
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#define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
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#define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
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#define TST1_LEAVE U1++; }
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#define TST2_LEAVE U2++; }
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#define ONE_ITERATION \
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\
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PTEST = PT1 >> 20; \
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\
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TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
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TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
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TST1_ENTER TST1_ENTER TST1_ENTER TST1_ENTER \
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\
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TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
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TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
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TST1_LEAVE TST1_LEAVE TST1_LEAVE TST1_LEAVE \
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\
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PTX = (PT1 >> 18) & 7; \
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PT1 &= 0x1FFF; \
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PT2 &= 0x1FFF; \
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CLK = (int) mbedtls_timing_hardclock(); \
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\
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i = 0; \
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A = &WALK[PT1 ]; RES[i++] ^= *A; \
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B = &WALK[PT2 ]; RES[i++] ^= *B; \
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C = &WALK[PT1 ^ 1]; RES[i++] ^= *C; \
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D = &WALK[PT2 ^ 4]; RES[i++] ^= *D; \
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\
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IN = (*A >> (1)) ^ (*A << (31)) ^ CLK; \
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*A = (*B >> (2)) ^ (*B << (30)) ^ CLK; \
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*B = IN ^ U1; \
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*C = (*C >> (3)) ^ (*C << (29)) ^ CLK; \
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*D = (*D >> (4)) ^ (*D << (28)) ^ CLK; \
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\
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A = &WALK[PT1 ^ 2]; RES[i++] ^= *A; \
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B = &WALK[PT2 ^ 2]; RES[i++] ^= *B; \
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C = &WALK[PT1 ^ 3]; RES[i++] ^= *C; \
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D = &WALK[PT2 ^ 6]; RES[i++] ^= *D; \
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\
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if( PTEST & 1 ) SWAP( A, C ); \
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\
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IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \
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*A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \
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*B = IN; CLK = (int) mbedtls_timing_hardclock(); \
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*C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \
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*D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \
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\
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A = &WALK[PT1 ^ 4]; \
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B = &WALK[PT2 ^ 1]; \
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\
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PTEST = PT2 >> 1; \
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\
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PT2 = (RES[(i - 8) ^ PTY] ^ WALK[PT2 ^ PTY ^ 7]); \
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PT2 = ((PT2 & 0x1FFF) & (~8)) ^ ((PT1 ^ 8) & 0x8); \
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PTY = (PT2 >> 10) & 7; \
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\
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TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
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TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
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TST2_ENTER TST2_ENTER TST2_ENTER TST2_ENTER \
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\
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TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
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TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
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TST2_LEAVE TST2_LEAVE TST2_LEAVE TST2_LEAVE \
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\
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C = &WALK[PT1 ^ 5]; \
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D = &WALK[PT2 ^ 5]; \
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\
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RES[i++] ^= *A; \
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RES[i++] ^= *B; \
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RES[i++] ^= *C; \
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RES[i++] ^= *D; \
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\
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IN = (*A >> ( 9)) ^ (*A << (23)) ^ CLK; \
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*A = (*B >> (10)) ^ (*B << (22)) ^ CLK; \
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*B = IN ^ U2; \
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*C = (*C >> (11)) ^ (*C << (21)) ^ CLK; \
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*D = (*D >> (12)) ^ (*D << (20)) ^ CLK; \
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\
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A = &WALK[PT1 ^ 6]; RES[i++] ^= *A; \
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B = &WALK[PT2 ^ 3]; RES[i++] ^= *B; \
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C = &WALK[PT1 ^ 7]; RES[i++] ^= *C; \
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D = &WALK[PT2 ^ 7]; RES[i++] ^= *D; \
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\
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IN = (*A >> (13)) ^ (*A << (19)) ^ CLK; \
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*A = (*B >> (14)) ^ (*B << (18)) ^ CLK; \
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*B = IN; \
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*C = (*C >> (15)) ^ (*C << (17)) ^ CLK; \
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*D = (*D >> (16)) ^ (*D << (16)) ^ CLK; \
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\
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PT1 = ( RES[( i - 8 ) ^ PTX] ^ \
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WALK[PT1 ^ PTX ^ 7] ) & (~1); \
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PT1 ^= (PT2 ^ 0x10) & 0x10; \
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\
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for( n++, i = 0; i < 16; i++ ) \
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hs->pool[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i];
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/*
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* Entropy gathering function
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*/
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static void havege_fill( mbedtls_havege_state *hs )
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{
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int i, n = 0;
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int U1, U2, *A, *B, *C, *D;
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int PT1, PT2, *WALK, RES[16];
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int PTX, PTY, CLK, PTEST, IN;
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WALK = hs->WALK;
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PT1 = hs->PT1;
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PT2 = hs->PT2;
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PTX = U1 = 0;
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PTY = U2 = 0;
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(void)PTX;
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memset( RES, 0, sizeof( RES ) );
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while( n < MBEDTLS_HAVEGE_COLLECT_SIZE * 4 )
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{
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ONE_ITERATION
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ONE_ITERATION
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ONE_ITERATION
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ONE_ITERATION
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}
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hs->PT1 = PT1;
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hs->PT2 = PT2;
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hs->offset[0] = 0;
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hs->offset[1] = MBEDTLS_HAVEGE_COLLECT_SIZE / 2;
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}
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/*
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* HAVEGE initialization
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*/
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void mbedtls_havege_init( mbedtls_havege_state *hs )
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{
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memset( hs, 0, sizeof( mbedtls_havege_state ) );
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havege_fill( hs );
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}
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void mbedtls_havege_free( mbedtls_havege_state *hs )
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{
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if( hs == NULL )
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return;
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mbedtls_zeroize( hs, sizeof( mbedtls_havege_state ) );
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}
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/*
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* HAVEGE rand function
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*/
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int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len )
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{
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int val;
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size_t use_len;
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mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng;
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unsigned char *p = buf;
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while( len > 0 )
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{
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use_len = len;
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if( use_len > sizeof(int) )
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use_len = sizeof(int);
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if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE )
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havege_fill( hs );
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val = hs->pool[hs->offset[0]++];
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val ^= hs->pool[hs->offset[1]++];
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memcpy( p, &val, use_len );
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len -= use_len;
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p += use_len;
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}
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return( 0 );
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}
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#endif /* MBEDTLS_HAVEGE_C */
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