
Product
Socket Now Protects the Chrome Extension Ecosystem
Socket is launching experimental protection for Chrome extensions, scanning for malware and risky permissions to prevent silent supply chain attacks.
This package has been deprecated and replaced with the Medo.Uuid7 package. I am keeping it here just as a reference.
The UUID7 library is an implementation of the UUID version 7 variant as defined in the new UUID specification, which introduces a time-ordered value field derived from the timestamp source. It offers improved entropy characteristics compared to versions 1 or 6 of the UUID standard. The inherent monotonicity of UUID version 7 makes it an excellent choice for utilization as a binary database key.
Newer optimized versions are available in Medo.Uuid7 package.
Features:
You can find packaged library at NuGet.
To generate a new database-friendly UUID v7, simply call NewUuid7
method:
using System;
using Medo;
var uuid = Uuid7.NewUuid7(); // or 'Uuid7.NewGuid()'
Console.WriteLine($"UUID : {uuid}");
Alternatively, if a fully random UUID v4 is desired, call NewUuid4
method:
using System;
using Medo;
var uuid = Uuid7.NewUuid4();
Console.WriteLine($"UUID : {uuid}");
If higher performance is needed and per-thread seqencing is sufficient, you can instantiate UUID directly:
using System;
using Medo;
var uuid = new Uuid7();
Console.WriteLine($"UUID : {uuid}");
Buffering of random numbers significantly increases performance at the cost of
less frequent but bigger requests toward random number generator. If buffering
is not desired (e.g. only a small count of UUIDs is needed), you can disable it
using UUID7_NO_RANDOM_BUFFER
preprocessor constant.
<PropertyGroup>
<DefineConstants>UUID7_NO_RANDOM_BUFFER</DefineConstants>
</PropertyGroup>
Note that this will decrease performance significantly.
The format of UUIDv7 is as specified below.
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_tx_ms: 48 bit big-endian unsigned number of Unix epoch timestamp.
ver:
4 bit UUIDv7 version. Always 0111
.
rand_a: 12 bits of pseudo-random data.
var:
2 bit variant. Always 10
.
rand_b: Additional 62 bits of pseudo-random data.
As monotonicity is important for UUID version 7 generation, this implementation implements most of monotonic random counter recommendations.
Implementation uses randomly seeded 26 bit monotonic counter (25 random bits + 1 rollover guard bit) with a 4-bit increment.
Counter uses 12-bits from rand_a field and it "steals" 14 bits from rand_b field. Counter will have its 25 bits fully randomized each millisecond tick. Within the same millisecond tick, counter will be randomly increased using 4 bit increment.
In the case of multithreaded use, the counter seed is different for each thread.
In the worst case, this implementation guarantees at least 2^21 monotonically increasing UUIDs per millisecond. Up to 2^23 monotonically increasing UUID values per millisecond can be expected on average. Monotonic increase for each generated value is guaranteed on per thread basis.
The last 48 bits are filled with random data that is different for each generated UUID.
As each UUID uses 48 random bits in addition to 25 random bits from the seeded counter, this means we have at least 73 bits of entropy (without taking 48-bit timestamp into account).
With those implementation details in mind, the final layout is defined as below.
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 | counter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|var| counter | random |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| random |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
unix_tx_ms: 48 bit big-endian unsigned number of Unix epoch timestamp.
ver:
4 bit UUIDv7 version. Always 0111
.
var:
2 bit variant. Always 10
.
counter: 26 bit big-endian unsigned counter.
random: 48 bits of random data.
While this UUID should be handled and stored in its binary 128 bit form, it's often useful to provide a textual representation.
This is a standard hexadecimal representation of UUID with dashes separating various components. Please note that this component separation doesn't necessarily correlate with any internal fields.
Example:
0185aee1-4413-7023-9109-bde493efe31d
Alternative string representation is Id25 (Base-35), courtesy of stevesimmons. While I have seen similar encodings used before, his implementation is the first one I saw being used on UUIDs. Since it uses only numbers and lowercase characters, it actually retains lexicographical sorting property the default UUID text format has.
UUID will always fit in 25 characters.
Example:
0672016s27hx3fjxmn5ic1hzq
If more compact string representation is needed, one can use Id22 (Base-58) encoding. This is the same encoding Bitcoin uses for its keys.
UUID will always fit in 22 characters.
Example:
1BuKkq6yWzmN2fCaHBjCRr
FAQs
Unknown package
We found that uuid7 demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Product
Socket is launching experimental protection for Chrome extensions, scanning for malware and risky permissions to prevent silent supply chain attacks.
Product
Add secure dependency scanning to Claude Desktop with Socket MCP, a one-click extension that keeps your coding conversations safe from malicious packages.
Product
Socket now supports Scala and Kotlin, bringing AI-powered threat detection to JVM projects with easy manifest generation and fast, accurate scans.