Because Version 5 uses the SHA-1 hashing algorithm, it is generally more secure and recommended than Version 3 which uses MD5. you want to always get the same ID for a given string. Use Version 3 or 5 UUID generation if you need reproducible results, i.e.The IDs in Version 1 are generated based on time and MAC address and contain both a random and a constant element to identify the computer from which they were generated. If you need a unique random UUID and want to know which one was generated from your computer, use Version 1.If you simply need a unique random UUID without going into details, use Version 4.Note that the /gofrs/uuid package does not support UUID generation in version 2, but instead supports experimental versions 6 and 7 (not present in the example above). We have put together some key ideas to help you decide if you should use of UUID's in your system.Package main import ( "fmt" "log" "/gofrs/uuid" ) func main () Use version 5 if you want a unique identifier that can be recreated again (by your own system or another integrating system) based on the inputs name and namespace. You should generally be using version 4 if just want your identifiers to be random and unique. This article was a brief look at the different UUID versions. You would generally use v5 for the same reasons you would chose v3, opting for v3 only when integrating with older systems that use MD5 for hasing names. UUID v5 works the same as v3, only difference being that it uses SHA-1 as the hashing algorithm, while and UUID v3 uses MD5. ![]() However, there is now a chance that a UUID could be duplicated. Because of this, there is no way to identify information about the source by looking at the UUID. The bits that comprise a UUID v4 are generated randomly and with no inherent logic. Given such small chance of collision, v4's main use case is when you need to ensure that the generated identifier is truly unique across your entire application (and likely around the globe)Įxample: const uuidv4 = require('uuid/v4') The generation of a v4 UUID is much simpler to comprehend. This results in unique identifiers that cannot be replayed and have extremely low change of being guessed. Instead, v4 generates unique identifiers based on random numbers (pseudo-random). UUID v4 differs from other versions in that it is not based on any easily reproducible data (MAC/timestamp for v1, name/namespace for v3 and v5). When compared with UUID v1, brute forcing UUID v3 is much more difficult. The generated output UUID, does not allow for easy reverse engineering the input values. The use case for UUID v3 is to generate unique identifiers from a name and namespace input in a deterministic way: given same input, always generate the same output. In the example above, uuidv3.DNS maps to a UUID value specified in the RFC 4122, but you can also provide any other valid UUID as well: const uuidv3 = require('uuid/v3')Ĭonst customNamespace = 'c6235813-3ba4-3801-ae84-e0a6ebb7d138' This namespace identifier must be a valid UUID.įor example: const uuidv3 = require('uuid/v3') domain or URL) and a namespace identifier. UUID v3 generates values by hashing (MD5) a name (eg. You should not use this version, as collision chance per domain/identifier is high. This version uses the MAC address and timestamp (much like version 1), but also allows you to include a domain and identifier in the UUID. UUID v2 are often left out of many implementations due to not being specified in the RFC4122. Uuid = uuidv1()Ĭonsole.log(uuid = newUuid) // true UUID version 2 If this is important for your application, see the alternatives bellow.Įxample code: const uuidv1 = require('uuid/v1') UUID v1 is easier to guess than some of the other versions. This means that if you know the MAC address and timestamp you could generate again the same UUID. This function returns a version 4 (random) UUID. The UUID v1 uses a computer identifier (typically your MAC address) and the timestamp to generate the unique identifiers. PostgreSQL includes one function to generate a UUID: genrandomuuid () uuid. Even though you should generally favor using v4 and v5, that doesn't mean v5 is better than v4. As we are going to see bellow, when it comes to UUID's, different versions have different use cases. Ever wonder what are the differences between UUID versions? If so, this short article for you.
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