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Is UUID secure?
Don’t rely on UUIDs for security. Never use UUIDs for things like session identifiers. The standard itself warns implementors to “not assume that UUIDs are hard to guess; they should not be used as security capabilities (identifiers whose mere possession grants access, for example).”
What is UUID version?
A universally unique identifier (UUID) is a 128-bit label used for information in computer systems. The term globally unique identifier (GUID) is also used, often in software created by Microsoft. When generated according to the standard methods, UUIDs are, for practical purposes, unique.
Is the universally unique identifier used for all UUIDs?
These fields correspond to those in version 1 and 2 UUIDs (that is, time-based UUIDs), but the same 8-4-4-4-12 representation is used for all UUIDs, even for UUIDs constructed differently. RFC 4122 Section 3 requires that the characters be generated in lower case, while being case-insensitive on input.
Why are UUIDs generated every time they are generated?
You are guaranteed to get unique UUIDs every time they are generated. An attacker may be able to get the exact timestamp, clock sequence and node (MAC address) of the system from an arbitrary UUID – Cost of anonymity. If an attacker is in possession of previous UUIDs generated from a system, it’s much easier to predict future ones.
How many versions of the UUID are there?
There are 5 different versions of UUIDs, excluding the Nil UUID version, which is a special case UUID where all its bytes are set to 0, and most contain some variants that allow for special cases specific to vendors like Microsoft. Version 1 and 2 use time-based sources (a 60 bit timestamp sourced from the system clock) for its randomness.
How is a version 1 UUID traced back to a computer?
Usage of the node’s network card MAC address for the node ID means that a version-1 UUID can be tracked back to the computer that created it. Documents can sometimes be traced to the computers where they were created or edited through UUIDs embedded into them by word processing software.