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Hypersequent's UUID7

This is a Go library for generating UUIDv7 based on RFC 9562 — the new UUID specification published in May 2024.

This library also implements a custom string encoding for UUIDv7, which is lexicographically sortable. This string encoding is not defined in RFC 9562 and is based on the Base58 encoding used in Bitcoin.

To make string representation visually more distinguishable from other UUIDs, there is a dash _ character inserted after the first 9 characters.

Example:

1C3XR6Gzv_es6ViopPLabMW
1C3XR6Gzv_gnTYagGW7m6AU
1C3VGAJyH_iXkB2HfuhEusP
1C3Rttz29_K2U2o4AdhPF5b

Binary format

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           unix_ts_ms                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          unix_ts_ms           |  ver  |       rand_a          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |var|                        rand_b                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            rand_b                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  • unix_ts_ms is filled with Go's time.Now().UnixNano() / 1e6
  • ver is 0b0111 for UUIDv7 (RFC 9562)
  • rand_a is filled using "Replace Leftmost Random Bits with Increased Clock Precision" (Method 3 in RFC 9562)
  • var is 0b10 for UUIDv7 (RFC 9562)
  • rand_b is cryptographically random bits, generated using Go's crypto/rand package

String Encoding

The UUID is encoded using Base58 encoding using BTC alphabet, which is the same as the one used in Bitcoin. Bitcoin address checksum is not used.

The encoded string is always 23 characters long (padded with leading "zero" digit 1 if needed).

To make string representation visually more distinguishable from other UUIDs, there is a dash _ character inserted after the first 9 characters.

String representation is sortable lexicographically, which a useful property when using as keys in databases.

Usage

package main

import "fmt"
import "github.com/hypersequent/uuid7"

func main() {
    uuid := uuid7.NewString() // returns a 22 character long string like "1C3Rttz29_K2U2o4AdhPF5b" 
    fmt.Println(uuid)
}

Dependencies

License

MIT