Jitendra Ojha

Backend engineer

Oct 13, 2015

Quoting from this page:

4-byte value representing the seconds since the Unix epoch,
3-byte machine identifier,
2-byte process id, and
3-byte counter, starting with a random value.

This looks one effective way of generating UUIDs. Negligible (or no) duplicates, I guess.

Jitendra Ojha

Backend engineer

Oct 20, 2015

@remco Wow..

Remco Boerma

CTO@NPO, python dev, dba

Oct 19, 2015

Indeed. It was this kind of UUID that lead to the arrest of an author of the melissa virus because guid's in that day were created with the machine info. So by looking at the used GUID in a word document in which contained the virus the feds found the origin.

Jan Vladimir Mostert

Idea Incubator

Oct 14, 2015

I don't think that's a UUID per the definition of UUID, but it's interesting to see how Mongo generates their objectIds. The IDs are predictable though, so not useful for secure tokens.

Comment by Jitendra Ojha on "How secure are your GUID / UUID (Universally Unique Identifier)?" | Hashnode

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