There is no difference between &#x2F;dev&#x2F;random and &#x2F;dev&#x2F;urandom in the Linux kernel, other than &#x2F;dev&#x2F;random blocks when the entropy estimate is low or depleted. Both source them same CSPRNG, which is based on SHA-1. &#x2F;dev&#x2F;urandom is absolutely recommended for long-term keys.