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#ifndef _IPXE_RTC_ENTROPY_H
#define _IPXE_RTC_ENTROPY_H
/** @file
*
* RTC-based entropy source
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#ifdef ENTROPY_RTC
#define ENTROPY_PREFIX_rtc
#else
#define ENTROPY_PREFIX_rtc __rtc_
#endif
/**
* min-entropy per sample
*
* @ret min_entropy min-entropy of each sample
*/
static inline __always_inline double
ENTROPY_INLINE ( rtc, min_entropy_per_sample ) ( void ) {
/* The min-entropy has been measured on several platforms
* using the entropy_sample test code. Modelling the samples
* as independent, and using a confidence level of 99.99%, the
* measurements were as follows:
*
* qemu-kvm : 7.38 bits
* VMware : 7.46 bits
* Physical hardware : 2.67 bits
*
* We choose the lowest of these (2.67 bits) and apply a 50%
* safety margin to allow for some potential non-independence
* of samples.
*/
return 1.3;
}
extern uint8_t rtc_sample ( void );
/**
* Get noise sample
*
* @ret noise Noise sample
* @ret rc Return status code
*/
static inline __always_inline int
ENTROPY_INLINE ( rtc, get_noise ) ( noise_sample_t *noise ) {
/* Get sample */
*noise = rtc_sample();
/* Always successful */
return 0;
}
#endif /* _IPXE_RTC_ENTROPY_H */
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