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/*
* viapadlock.h -- VIA PadLock interface
*
* Copyright 2004,2005 Henrique de Moraes Holschuh <hmh@debian.org>
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef VIAPADLOCK__H
#define VIAPADLOCK__H
#define _GNU_SOURCE
#include "rng-tools-config.h"
#ifdef VIA_ENTSOURCE_DRIVER
#include <unistd.h>
#include <sys/types.h>
#include <stdint.h>
typedef enum {
VIAPADLOCK_RNG1_SOURCE_A = 0,
VIAPADLOCK_RNG1_SOURCE_B = 1,
VIAPADLOCK_RNG1_SOURCE_AB = 2
} viapadlock_noise_source_t;
typedef struct {
unsigned int dc_bias; /* DC bias, 0 = default */
unsigned int string_filter; /* String filter length, 0=disabled */
viapadlock_noise_source_t /* Noise source */
noise_source;
unsigned int whitener; /* Whitener, 1=enabled, 0=disabled */
unsigned int divisor; /* XSTORE divisor to use, 0-3 */
} viapadlock_rng_config_t;
/*
* Initialize VIA PadLock RNGs
*
* devicepath is the path to the cpuid and msr devices,
* with a %u escape where the CPU number should go.
* NULL implies the default path (/dev/cpu/%u)
*
* All RNGs in a system must be exactly of the same type,
* and all CPUs must have a functional RNG.
*
* Returns:
* 0 if no functional VIA PadLock RNG set was detected
* 1 if a functional VIA PadLock RNG set was detected
* -1 if an error happened (errno will be set)
*/
extern int viapadlock_rng_init(const char* devicepath);
/*
* Free up resources used by the VIA PadLock RNGs
* (does not disable or otherwise touch the RNGs)
*/
extern void viapadlock_rng_free(void);
/*
* Generate recommended configuration for the given quality.
*
* Returns the estimated H (entropy per bit of data).
*
* quality:
* 0: default for entropy pool seeding
* 1 (low) < 2 (medium) < 3+ (high)
*
* If the random data will be used directly, always use quality=HIGH.
*
* The bandwidth available from the RNG decreases with quality by a factor
* of approximately 2 per step.
*
* We always enable as many sources as possible (as we assume them to be
* of equal quality and completely uncoupled). The whitener is always enabled,
* as the RNG is not good enough for crypto without it. We never use the full
* RNG bandwidth because of measurable correlation between two consecutive bits
* from the same source. The string filter is always disabled, so that we get
* to know (through FIPS test failures) if the combined RNG streams fail a long
* run test.
*/
extern double viapadlock_rng_generate_config(unsigned int quality,
viapadlock_rng_config_t* cfg);
/*
* Enable/disable VIA PadLock RNGs
*
* enable: 1 = enable, 0 = disable
*
* If enabling the RNGs, and cfg is not NULL, the RNGs are configured.
* This is required the first time the RNGs are enabled.
*
* Returns -1 on error (errno set), 0 otherwise
*/
extern int viapadlock_rng_enable(unsigned int enable,
viapadlock_rng_config_t* cfg);
/*
* Read data from a VIA PadLock RNG set
*
* Returns the number of bytes read if no errors happen
* -1 if an error happened, with errno set.
*/
extern ssize_t viapadlock_rng_read(void* buf, size_t size);
#endif /* VIA_ENTSOURCE_DRIVER */
#endif /* VIAPADLOCK__H */
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