diff options
Diffstat (limited to 'src/include/ipxe/entropy.h')
| -rw-r--r-- | src/include/ipxe/entropy.h | 133 |
1 files changed, 102 insertions, 31 deletions
diff --git a/src/include/ipxe/entropy.h b/src/include/ipxe/entropy.h index 108c376..240feac 100644 --- a/src/include/ipxe/entropy.h +++ b/src/include/ipxe/entropy.h @@ -42,6 +42,76 @@ typedef unsigned int min_entropy_t; #define MIN_ENTROPY( bits ) \ ( ( min_entropy_t ) ( (bits) * MIN_ENTROPY_SCALE ) ) +/** + * Repetition count test state + * + * This is the state for the repetition Count Test defined in ANS + * X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.2. + */ +struct entropy_repetition_count_test { + /** + * A = the most recently seen sample value + */ + noise_sample_t most_recent_sample; + /** + * B = the number of times that value A has been seen in a row + */ + unsigned int repetition_count; + /** + * C = the cutoff value above which the repetition test should fail + * + * Filled in by entropy_init(). + */ + unsigned int cutoff; +}; + +/** + * Adaptive proportion test state + * + * This is the state for the Adaptive Proportion Test for the Most + * Common Value defined in ANS X9.82 Part 2 (October 2011 Draft) + * Section 8.5.2.1.3. + */ +struct entropy_adaptive_proportion_test { + /** + * A = the sample value currently being counted + */ + noise_sample_t current_counted_sample; + /** + * S = the number of samples examined in this run of the test so far + */ + unsigned int sample_count; + /** + * B = the current number of times that S (sic) has been seen + * in the W (sic) samples examined so far + */ + unsigned int repetition_count; + /** + * C = the cutoff value above which the repetition test should fail + * + * Filled in by entropy_init(). + */ + unsigned int cutoff; +}; + +/** + * Startup test state + * + * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.5 requires + * that at least one full cycle of the continuous tests must be + * performed at start-up. + */ +struct entropy_startup_test { + /** Number of startup tests performed */ + unsigned int tested; + /** + * Number of startup tests required for one full cycle + * + * Filled in by entropy_init(). + */ + unsigned int count; +}; + /** An entropy source */ struct entropy_source { /** Name */ @@ -59,34 +129,19 @@ struct entropy_source { * Filled in by entropy_init(). */ min_entropy_t min_entropy_per_sample; + /** Repetition count test state */ + struct entropy_repetition_count_test repetition_count_test; + /** Adaptive proportion test state */ + struct entropy_adaptive_proportion_test adaptive_proportion_test; + /** Startup test state */ + struct entropy_startup_test startup_test; /** - * Repetition count test cutoff value - * - * This is the cutoff value for the Repetition Count Test - * defined in ANS X9.82 Part 2 (October 2011 Draft) Section - * 8.5.2.1.2. - * - * Filled in by entropy_init(). - */ - unsigned int repetition_count_cutoff; - /** - * Adaptive proportion test cutoff value - * - * This is the cutoff value for the Adaptive Proportion Test - * defined in ANS X9.82 Part 2 (October 2011 Draft) Section - * 8.5.2.1.3.1.2. - * - * Filled in by entropy_init(). - */ - unsigned int adaptive_proportion_cutoff; - /** - * Startup test count + * Failure status (if any) * - * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.5 - * requires that at least one full cycle of the continuous - * tests must be performed at start-up. + * Any failure of an entropy source is regarded as permanent. */ - unsigned int startup_test_count; + int rc; + /** * Enable entropy gathering * @@ -140,6 +195,22 @@ extern int get_entropy_input_tmp ( min_entropy_t min_entropy, uint8_t *tmp, #define ENTROPY_HASH_DF_OUTLEN_BYTES SHA256_DIGEST_SIZE /** + * Get noise sample + * + * @v source Entropy source + * @ret noise Noise sample + * @ret rc Return status code + * + * This is the GetNoise function defined in ANS X9.82 Part 2 + * (October 2011 Draft) Section 6.5.2. + */ +static inline __attribute__ (( always_inline )) int +get_noise ( struct entropy_source *source, noise_sample_t *noise ) { + + return source->get_noise ( noise ); +} + +/** * Obtain entropy input * * @v min_entropy_bits Minimum amount of entropy, in bits @@ -445,13 +516,13 @@ entropy_init ( struct entropy_source *source, /* Record min-entropy per sample and test cutoff values */ source->min_entropy_per_sample = min_entropy_per_sample; - source->repetition_count_cutoff = repetition_count_cutoff; - source->adaptive_proportion_cutoff = adaptive_proportion_cutoff; - source->startup_test_count = startup_test_count; + source->repetition_count_test.cutoff = repetition_count_cutoff; + source->adaptive_proportion_test.cutoff = adaptive_proportion_cutoff; + source->startup_test.count = startup_test_count; } -extern int entropy_enable ( void ); -extern void entropy_disable ( void ); -extern int get_noise ( noise_sample_t *noise ); +extern int entropy_enable ( struct entropy_source *source ); +extern void entropy_disable ( struct entropy_source *source ); +extern int get_noise ( struct entropy_source *source, noise_sample_t *noise ); #endif /* _IPXE_ENTROPY_H */ |