UUID Generator (version 1)

Generate a Universally Unique IDentifier (UUID) version 1 (time-based), a 128-bit identifier derived from the current timestamp and a random node. UUID is also known as Globally Unique IDentifier (GUID).

Generated UUID:

 

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More about UUID version 1

UUID version 1 is a time-based UUID that encodes the timestamp and a node identifier into a 128-bit value. Here is how a UUID version 1 is constructed:

  1. A 60-bit timestamp is computed from the current time, measured in 100-nanosecond intervals since October 15, 1582 (the date of Gregorian calendar reform). This timestamp is split across three fields: time_low (32 bits), time_mid (16 bits), and time_hi_and_version (12 bits + 4 version bits).

  2. The version number is set to 0001 in binary (or 1 in hexadecimal) in the most significant 4 bits of the 7th byte.

  3. A 14-bit clock sequence is generated randomly to avoid duplicates if the clock is set backward or the node changes. The variant bits 10 are set in the most significant 2 bits of the 9th byte.

  4. A 48-bit node identifier is included. In the original specification this is the MAC address, but for privacy and portability, a random node with the multicast bit set is commonly used instead.

The resulting UUID has the format: xxxxxxxx-xxxx-1xxx-yxxx-xxxxxxxxxxxx, where the 1 indicates version 1 and y represents the variant. UUID v1 values contain an embedded timestamp, which means they can be roughly sorted by creation time, but they are not cryptographically random.