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https://github.com/yuzu-emu/mbedtls.git
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8850e2e367
The elements of the HAVEGE state are manipulated with bitwise operations, with the expectations that the elements are 32-bit unsigned integers (or larger). But they are declared as int, and so the code has undefined behavior. Clang with Asan correctly points out some shifts that reach the sign bit. Use unsigned int internally. This is technically an aliasing violation since we're accessing an array of `int` via a pointer to `unsigned int`, but since we don't access the array directly inside the same function, it's very unlikely to be compiled in an unintended manner.
247 lines
9 KiB
C
247 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) { unsigned *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 = (unsigned) 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 = (unsigned) 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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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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unsigned i, n = 0;
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unsigned U1, U2, *A, *B, *C, *D;
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unsigned PT1, PT2, *WALK, *POOL, RES[16];
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unsigned PTX, PTY, CLK, PTEST, IN;
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WALK = (unsigned *) hs->WALK;
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POOL = (unsigned *) hs->pool;
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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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