# Generating Secure Random Numbers in R

```
knitr::opts_chunk$set(comment = "")
library(openssl)
```

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)
```

Bytes are 8 bit and hence can have `2^8 = 256`

possible values.

`as.numeric(rnd)`

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

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

## 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)`

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))
```