bigdRand.h File Reference

Interface for BigDigits "bd" random number functions using a "pretty-good" internal RNG. More...

Functions
bdigit_t	bdRandDigit (void)
	Generate a single random digit using internal RNG. More...
size_t	bdRandomBits (BIGD a, size_t nbits)
	Generate a random BIGD number of bit length at most nbits using internal RNG. More...
size_t	bdRandomNumber (BIGD a, BIGD n)
	Generate a number at random from a uniform distribution in [0, n-1]. More...
int	bdRandomOctets (unsigned char *bytes, size_t nbytes, const unsigned char *seed, size_t seedlen)
	Generate array of random octets (bytes) using internal RNG. More...

Detailed Description

Interface for BigDigits "bd" random number functions using a "pretty-good" internal RNG.

The internal random number generator (RNG)

The internal RNG uses a variant of the random number generation algorithm in Appendix A of ANSI X9.31-1998, but using the Tiny Encryption Algorithm (TEAX) instead of the Data Encryption Algorithm (DEA). It uses the current time and process ID as a seed. Although not strictly crypto secure, it is "pretty good", and certainly much better than anything using the built-in rand() function in C. Look at the source code and make your own call.

If you want proper cryptographic security, use the bdRandomSeeded() function with a call to a secure RNG function that you trust.

Function Documentation

bdigit_t bdRandDigit

(

void

)

Generate a single random digit using internal RNG.

size_t bdRandomBits	(	BIGD	a,
		size_t	nbits
	)

Generate a random BIGD number of bit length at most nbits using internal RNG.

Parameters

[out]	a	to receive generated random number
[in]	nbits	maximum number of bits

Returns

Number of digits actually set

size_t bdRandomNumber	(	BIGD	a,
		BIGD	n
	)

Generate a number at random from a uniform distribution in [0, n-1].

int bdRandomOctets	(	unsigned char *	bytes,
		size_t	nbytes,
		const unsigned char *	seed,
		size_t	seedlen
	)

Generate array of random octets (bytes) using internal RNG.

Remarks

This function is in the correct form for BD_RANDFUNC.