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)
  26 48 db 36 ab 7c c0 dc 9f fc

Bytes are 8 bit and hence can have 2^8 = 256 possible values.

as.numeric(rnd)
   38  72 219  54 171 124 192 220 159 252

Each random byte can be decomposed into 8 random bits (booleans)

x <- rand_bytes(1)
as.logical(rawToBits(x))
 FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE

## Secure Random Numbers

rand_num is a simple (2 lines) wrapper to rand_bytes to generate random numbers (doubles) between 0 and 1.

rand_num(10)
  0.7575298 0.5480147 0.4906946 0.8842838 0.9457880 0.1555431 0.6475413
 0.6884475 0.3908591 0.8928938

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)) 