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TRNG driver implementation for the CC26X2 family.
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This file should only be included in the board file to fill the TRNG_config struct.
The CC26X2 family has a dedicated hardware TRNG based on sampling multiple free running oscillators. With all FROs enabled, the TRNG hardware generates 64 bits of entropy approximately every 5ms. The driver implementation chains multiple 64-bit entropy generation operations together to generate an arbitrary amount of entropy.
When using TRNG_generateEntropyLessThan() and TRNG_generateEntropyNonZeroLessThan(), there is a restriction on the maximum entropy length that may be generated. The driver implements a variant from BSI Technical Guideline TR-03111 to generate a random number less than some upper bound that is also unbiased. This requires generating more entropy than explicitely requested and performing modulo operations on it. This intermediate entropy is stored in the PKA RAM before the PKA reduces it. This limits the maximum length of the generated entropy to 768 bytes. In practice, this should not prove to be a problem. The largest number you would reasonably want to generate that is less than some upper bound is a private key for the NIST P521 curve. It has a 66-byte curve parameter length and thus also private key length.
Since TRNG_generateEntropyLessThan() and TRNG_generateEntropyNonZeroLessThan() both use the PKA module, the driver must acquire the PKA semaphore as well as the TRNG semaphore. This is implemented transparently to the application and the driver will return an error if it did not acquire both semaphores for the above operations.
The driver implementation does not perform runtime checks for most input parameters. Only values that are likely to have a stochastic element to them are checked (such as whether a driver is already open). Higher input paramter validation coverage is achieved by turning on assertions when compiling the driver.
#include <stdint.h>#include <stdbool.h>#include <ti/drivers/Power.h>#include <ti/drivers/TRNG.h>#include <ti/drivers/cryptoutils/cryptokey/CryptoKey.h>#include <ti/drivers/dpl/HwiP.h>#include <ti/drivers/dpl/SwiP.h>#include <ti/drivers/dpl/SemaphoreP.h>Go to the source code of this file.
Data Structures | |
| struct | TRNGCC26X2_HWAttrs |
| TRNGCC26X2 Hardware Attributes. More... | |
| struct | TRNGCC26X2_Object |
| TRNGCC26XX Object. More... | |
Typedefs | |
| typedef struct TRNGCC26X2_HWAttrs | TRNGCC26X2_HWAttrs |
| TRNGCC26X2 Hardware Attributes. More... | |
| typedef struct TRNGCC26X2_Object | TRNGCC26X2_Object |
| TRNGCC26XX Object. More... | |
| typedef struct TRNGCC26X2_HWAttrs TRNGCC26X2_HWAttrs |
TRNGCC26X2 Hardware Attributes.
TRNG26X2 hardware attributes should be included in the board file and pointed to by the TRNG_config struct.
| typedef struct TRNGCC26X2_Object TRNGCC26X2_Object |
TRNGCC26XX Object.
The application must not access any member variables of this structure!