[linux-l] UUIDs - Vorteile ??

[Norm@nSteinbach]

Ralph Angenendt wrote:
> Boris Kirkorowicz wrote:
>>> UUIDs sind per Definition chaotisch.
>> woher stammen die eigentlich? Sind das ausgelesene Seriennummern, Hashes
>> aus Partionsdaten, Zufallszahlen?
> Die manual page von uuid_generate gibt recht ausführlich Auskunft
> darüber.

Danke für den Tip! Ich hab die zwar auf meinem System nicht gefunden 
(weil ichs nicht benutze), aber im Netz (weils mich trotzdem interessiert):

//===http://pwet.fr/man/linux/fonctions_bibliotheques/uuid_generate===//
[...]
DESCRIPTION

The uuid_generate function creates a new universally unique identifier 
(UUID). The uuid will be generated based on high-quality randomness from 
/dev/urandom, if available. If it is not available, then uuid_generate 
will use an alternative algorithm which uses the current time, the local 
ethernet MAC address (if available), and random data generated using a 
pseudo-random generator. The uuid_generate_random function forces the 
use of the all-random UUID format, even if a high-quality random number 
generator (i.e., /dev/urandom) is not available, in which case a 
pseudo-random generator will be subsituted. Note that the use of a 
pseudo-random generator may compromise the uniqueness of UUID's 
generated in this fashion. The uuid_generate_time function forces the 
use of the alternative algorithm which uses the current time and the 
local ethernet MAC address (if available). This algorithm used to be the 
default one used to generate UUID, but because of the use of the 
ethernet MAC address, it can leak information about when and where the 
UUID was generated. This can cause privacy problems in some 
applications, so the uuid_generate function only uses this algorithm if 
a high-quality source of randomness is not available. The UUID is 16 
bytes (128 bits) long, which gives approximately 3.4x10^38 unique values 
(there are approximately 10^80 elemntary particles in the universe 
according to Carl Sagan's Cosmos). The new UUID can reasonably be 
considered unique among all UUIDs created on the local system, and among 
UUIDs created on other systems in the past and in the future.
[...]
//====================================================================//


Viele Grüße,

Norm at n