diff options
Diffstat (limited to 'board/cr50/fips_rand.h')
| -rw-r--r-- | board/cr50/fips_rand.h | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/board/cr50/fips_rand.h b/board/cr50/fips_rand.h index 14eba3fe32..dca1f473bf 100644 --- a/board/cr50/fips_rand.h +++ b/board/cr50/fips_rand.h @@ -19,6 +19,29 @@ extern "C" { #define TRNG_SAMPLE_BITS 1 /** + * Initialize the true random number generator (TRNG) in FIPS-compliant + * way: + * 1. Set 1-bit alphabet + * 2. Set maximum possible range for internal ring-oscillator + * 3. Disable any other post-processing beyond #2 + **/ +void fips_init_trng(void); + +/** + * Returns random number with indication wherever reading is valid. This is + * different from rand() which doesn't provide any indication. + * High 32-bits set to zero in case of error; otherwise value >> 32 == 1 + * Use of uint64_t vs. struct results in more efficient code. + */ +uint64_t read_rand(void); + +/* Return true if read_rand() result contains valid random from TRNG. */ +static inline bool rand_valid(uint64_t rand) +{ + return (rand >> 32) != 0; +} + +/** * TRNG Health Tests * * If any of the approved continuous health tests are used by the entropy @@ -75,7 +98,7 @@ extern "C" { * over at least 4096 consecutive samples. * Note: This function can throw FIPS_FATAL_TRNG error * - * To hide latenccy of reading TRNG data, this test is executed in 2 stages + * To hide latency of reading TRNG data, this test is executed in 2 stages * @param stage is 0 or 1, choosing the stage. On each stage 2048 * samples are processed. Assuming that some other tasks can be executed * between stages, when TRNG FIFO if filled with samples. |