On Tuesday 14 December 2010 05:13:43 pm R. Reucher wrote:

> Well, I was refering to this statement from the Qt documentation:


> QUuid QUuid::createUuid()

> On any platform other than Windows, this function returns a new UUID with

> variant QUuid::DCE and version QUuid::Random. If the /dev/urandom device

> exists, then the numbers used to construct the UUID will be of

> cryptographic quality, which will make the UUID unique. Otherwise, the

> numbers of the UUID will be obtained from the local pseudo-random number

> generator (qrand(), which is seeded by qsrand()) which is usually not of

> cryptograhic quality, which means that the UUID can't be guaranteed to be

> unique.

> http://doc.qt.nokia.com/4.7/quuid.html#createUuid

Oh, the Qt 4.3 - 4.6 docs say just this about it:

Returns a new UUID of DCE variant, and Random type. The UUIDs generated are based on the platform specific pseudo-random generator, which is usually not a cryptographic-quality random number generator. Therefore, a UUID is not guaranteed to be unique cross application instances.


So, /dev/urandom support was added in Qt 4.7. Every earlier version uses only the pseudo-random number generator.

Cheers, René


René Reucher



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