Function hdk::random::random_bytes

pub fn random_bytes(number_of_bytes: u32) -> ExternResult<Bytes>

Get N cryptographically strong random bytes.

let five_bytes = random_bytes(5)?;

It’s not possible to generate random bytes from inside the wasm guest so the data is provided by the wasm host which implies operating system specific details re: randomness.

The bytes are cryptographically random in that they are unpredictable, to the quality of what host environment offers and the crypto implementation within holochain.

The bytes are not “secure” though:

• there’s no way to prove that a specific value was the result of random generation or not
• the bytes are open in memory and even (de)serialized several times between the host and guest

The bytes are not a performant or testable way to do statistical analysis (e.g. monte carlo). Rust provides several seedable PRNG implementations that are fast, repeatable and statistically high quality even if not suitable for crypto applications. If you need to do anything with statistics it is usually recommended to generate or provide a seed and then use an appropriate PRNG from there.

See the rand rust crate