Generating Secure Random Numbers in R

2026-03-05

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] e5 84 95 45 59 7f 07 8d c2 45

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

as.numeric(rnd)

 [1] 229 132 149  69  89 127   7 141 194  69

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

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

[1]  TRUE FALSE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE

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)

 [1] 0.84374710 0.89881485 0.29098216 0.82649726 0.35159241 0.02555826
 [7] 0.49835408 0.25192917 0.44369823 0.51634721

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))