Random number generation (TRNG, PRNG)

Functions
__STATIC_INLINE cy_en_crypto_status_t	Cy_Crypto_Prng_Init (CRYPTO_Type *base, uint32_t *lfsrSeedValues)
	This function initializes the PRNG (Pseudo Random Number Generator) parameters. More...
__STATIC_INLINE cy_en_crypto_status_t	Cy_Crypto_Prng (CRYPTO_Type *base, uint32_t max, uint32_t *randomNum)
	This function generates a Pseudo Random Number based on the initial seed values provided in Cy_Crypto_Prng_Init(). More...
cy_en_crypto_status_t	Cy_Crypto_Trng (CRYPTO_Type *base, uint32_t max, uint32_t *randomNum)
	This function generates a True Random Number. More...

Detailed Description

Function Documentation

Cy_Crypto_Prng_Init()

__STATIC_INLINE cy_en_crypto_status_t Cy_Crypto_Prng_Init	(	CRYPTO_Type *	base,
		uint32_t *	lfsrSeedValues
	)

This function initializes the PRNG (Pseudo Random Number Generator) parameters.

Invoking this function causes a restart of the pseudo-random sequence.

Note

Invoking this function multiple times with the same set of seed values results in the same sequence of random numbers with Cy_Crypto_Prng function. To obtain a different pseudo-random sequence, pass a different set of seed values for the LFSR registers. It is recommended to use Cy_Crypto_Trng() to generate random seed values for each initialization.

Parameters

base	Base address of the Crypto block registers
lfsrSeedValues	Pointer to an array of three seed values for the Linear Feedback Shift Registers - LFSR32, LFSR31 and LFSR29 respectively. Each seed value must be a non-zero, random number. Passing NULL will cause seed values to be generated internally, using the Cy_Crypto_Trng() function. In this case, ensure that Cy_Crypto_Trng() is not called from another thread until the this function returns.

Returns

cy_en_crypto_status_t

Function Usage

    /* Initialization seed values for pseudo random number generator.
       These can be any non-zero random numbers. Cy_Crypto_Trng function can be
       used to generate the initial seed values as well. If a NULL pointer is
       passed, the seed values are calculated and set internally.
    */
    #define LFSR32_INITSTATE      (0xd8959bc9)
    #define LFSR31_INITSTATE      (0x2bb911f8)
    #define LFSR29_INITSTATE      (0x060c31b7)

    #define MAX_PRNG_VALUE        (10000UL)

    /* Generated random number */
    uint32_t rndNum = 0;
    uint32_t lfsrSeedValues[3] = {LFSR32_INITSTATE, LFSR31_INITSTATE, LFSR29_INITSTATE};

    cy_en_crypto_status_t cryptoStatus;

    /* Initialize the pseudo random number generator */
    cryptoStatus = Cy_Crypto_Prng_Init(
                             CRYPTO,             /* Base address of the Crypto block registers */
                             lfsrSeedValues);    /* Seed value for the three LFSR registers */

    /* ... check for errors... */

    /* Generate a pseudo random number in the specified range */
    cryptoStatus = Cy_Crypto_Prng(
                             CRYPTO,           /* Base address of the Crypto block registers */
                             MAX_PRNG_VALUE,   /* Range of random number */
                             &rndNum);         /* Pointer to generated random number */

    /* ... check for errors... */

Cy_Crypto_Prng()

__STATIC_INLINE cy_en_crypto_status_t Cy_Crypto_Prng	(	CRYPTO_Type *	base,
		uint32_t	max,
		uint32_t *	randomNum
	)

This function generates a Pseudo Random Number based on the initial seed values provided in Cy_Crypto_Prng_Init().

Parameters

base	Base address of the Crypto block registers
max	Maximum value of the generated pseudo random number. The range of the pseudo random number generated is [0, max]. The max value can be any integer between 1 and 232 - 1 (1 to 4294967295).
randomNum	Pointer to the generated pseudo random number. This must be a pointer to a 32-bit number.

Returns

cy_en_crypto_status_t

Function Usage

    /* Initialization seed values for pseudo random number generator.
       These can be any non-zero random numbers. Cy_Crypto_Trng function can be
       used to generate the initial seed values as well. If a NULL pointer is
       passed, the seed values are calculated and set internally.
    */
    #define LFSR32_INITSTATE      (0xd8959bc9)
    #define LFSR31_INITSTATE      (0x2bb911f8)
    #define LFSR29_INITSTATE      (0x060c31b7)

    #define MAX_PRNG_VALUE        (10000UL)

    /* Generated random number */
    uint32_t rndNum = 0;
    uint32_t lfsrSeedValues[3] = {LFSR32_INITSTATE, LFSR31_INITSTATE, LFSR29_INITSTATE};

    cy_en_crypto_status_t cryptoStatus;

    /* Initialize the pseudo random number generator */
    cryptoStatus = Cy_Crypto_Prng_Init(
                             CRYPTO,             /* Base address of the Crypto block registers */
                             lfsrSeedValues);    /* Seed value for the three LFSR registers */

    /* ... check for errors... */

    /* Generate a pseudo random number in the specified range */
    cryptoStatus = Cy_Crypto_Prng(
                             CRYPTO,           /* Base address of the Crypto block registers */
                             MAX_PRNG_VALUE,   /* Range of random number */
                             &rndNum);         /* Pointer to generated random number */

    /* ... check for errors... */

Cy_Crypto_Trng()

cy_en_crypto_status_t Cy_Crypto_Trng	(	CRYPTO_Type *	base,
		uint32_t	max,
		uint32_t *	randomNum
	)

This function generates a True Random Number.

Note

True random number generation is slower than pseudo random number generation. For generating a large number of random numbers, it is recommended to use this function to obtain random seed values for PRNG and generate the random numbers by using the Cy_Crypto_Prng() function.

Parameters

base	Base address of the Crypto block registers
max	Maximum length of a random number, in the range of [1, 32] bits. The generated random number is in the range of [1, 2max].
randomNum	Pointer to the generated true random number. This must be a pointer to a 32-bit number.

Returns

cy_en_crypto_status_t

Function Usage

    #define MAX_TRNG_BIT_SIZE     (32UL)

    /* Generated random number */
    uint32_t rndNum = 0;

    cy_en_crypto_status_t cryptoStatus;

    /* Generate a true random number in the specified range */
    cryptoStatus = Cy_Crypto_Trng(
                             CRYPTO,             /* Base address of the Crypto block registers */
                             MAX_TRNG_BIT_SIZE,  /* Range of random number */
                             &rndNum);           /* Pointer to generated random number */

    /* ... check for errors... */