:sig
String random_bytes(u64 n)

:params
n : number of bytes to generate
return value : `n` cryptographically random bytes

:content
Returns `n` cryptographically secure random bytes, suitable for session IDs, tokens, and salts. The bytes are binary; wrap them with `base64_encode()` or `sha256_hex()` when you need printable text.

:example
String token = base64_encode(random_bytes(16));
print(random_bytes(16).length(), " raw bytes; as base64 token: ", token.length(), " chars\n");

:see
>sys
base64_encode
sha256_hex
