> If this is true, then /dev/urandom might split out unsafe bits (as unlikely it is), which to me sounds like a terrible idea when creating a key or similar ver

> If this is true, then /dev/urandom might split out unsafe bits (as unlikely it is), which to me sounds like a terrible idea when creating a key or similar very importants secrets. CSPRNGs such as /dev/urandom use the same cryptographic primitives that symmetric ciphers (such as AES, Twofish, Salsa20, ChaCha20, etc.) use. In the unlikely event that our CSPRNGs are broken (meaning /dev/urandom outputs "unsafe bits"), our symmetric ciphers will all be broken too. Therefore there is absolutely no point in insisting on using /dev/random to generate keys that will be used with symmetric ciphers. (That's a little hand-wavy but I hope you get the general idea.)