Does anyone have any idea why Linux has a distinction between /dev/random and /dev/urandom?
Legacy adherence to some defunct interface? Ignorance on the part of kernel devs (seems unlikely)?
Legacy adherence to some defunct interface? Ignorance on the part of kernel devs (seems unlikely)?
To quote Ted Tso (author of the above patch and the original writer of /dev/random in the first place)
The two other interfaces are two character devices /dev/random and * /dev/urandom. /dev/random is suitable for use when very high * quality randomness is desired (for example, for key generation or * one-time pads), as it will only return a maximum of the number of * bits of randomness (as estimated by the random number generator) * contained in the entropy pool. * * The /dev/urandom device does not have this limit, and will return * as many bytes as are requested. As more and more random bytes are * requested without giving time for the entropy pool to recharge, * this will result in random numbers that are merely cryptographically * strong. For many applications, however, this is acceptable.