I've been looking at ways to generate a strong 256 bit/32 byte symmetric key for the HMAC_SHA256 algorithm. I stumbled upon the /proc/sys/kernel/random/uuid file.
According to man random(4): "The read-only files uuid and boot_id contain random strings like 6fd5a44b-35f4-4ad4-a9b9-6b9be13e1fe9. The former is generated afresh for each read, the latter was generated once."
The string from cat /proc/sys/kernel/random/uuid
looks ideal for this purpose. I can remove the '-' chars and end up with a 32 bytes of randomness.
Is this a valid approach to generate a cryptographically strong source of keying material?