The rand_bytes
function binds to RAND_bytes
in OpenSSL to generate cryptographically strong pseudo-random bytes. See
the OpenSSL documentation for what this means.
rnd <- rand_bytes(10)
print(rnd)
[1] 86 a9 c0 73 fa 46 27 5d 1a 2a
Bytes are 8 bit and hence can have 2^8 = 256
possible
values.
as.numeric(rnd)
[1] 134 169 192 115 250 70 39 93 26 42
Each random byte can be decomposed into 8 random bits (booleans)
x <- rand_bytes(1)
as.logical(rawToBits(x))
[1] TRUE TRUE TRUE TRUE TRUE FALSE TRUE TRUE
rand_num
is a simple (2 lines) wrapper to
rand_bytes
to generate random numbers (doubles) between 0
and 1.
rand_num(10)
[1] 0.60764747 0.90806394 0.54155850 0.39304123 0.61983694 0.78611998
[7] 0.83655840 0.95580522 0.69971906 0.05443186
To map random draws from [0,1] into a probability density, we can use
a Cumulative
Distribution Function. For example we can combine qnorm
and rand_num
to simulate rnorm
:
# Secure rnorm
x <- qnorm(rand_num(1000), mean = 100, sd = 15)
hist(x)
Same for discrete distributions:
# Secure rbinom
y <- qbinom(rand_num(1000), size = 20, prob = 0.1)
hist(y, breaks = -.5:(max(y)+1))