Secure random number generation for mruby using system RNG facilities e.g. /dev/urandom, getrandom(2)
In cryptography circles, the prevailing advice is to use OS RNG functionality,
namely /dev/urandom or equivalent calls which use an OS-level CSPRNG to
produce random numbers.
This gem provides an easy-to-install repackaging of the randombytes
functionality from libsodium for the purpose of generating secure random
numbers trustworthy for use in cryptographic contexts, such as generating
cryptographic keys, initialization vectors, or nonces.
The following random number generators are utilized:
| Platform | RNG |
|---|---|
| Linux | getrandom(2) if available, otherwise /dev/urandom |
| Windows | RtlGenRandom CryptGenRandom without CryptoAPI deps |
| OpenBSD | arc4random(3) with ChaCha20 CSPRNG (not RC4) |
| Others | /dev/urandom |
Sysrandom.random_bytes # returns a 16 byte binary string
Sysrandom.random_bytes(64)
Sysrandom.random_bytes(" " * 10)
Sysrandom.random # returns a number
Sysrandom.uniform(upper_bound) # returns a number up to upper_bound
Sysrandom.base64 # returns a 16 byte binary string as base64
Sysrandom.base64(64)
Sysrandom.base64(" " * 10)
Sysrandom.hex # returns a 16 byte binary string as hex
Sysrandom.hex(64)
Sysrandom.hex(" " * 10)