UUIDv3

UUIDv3 is a version of the Universally Unique Identifier (UUID) standard that generates unique identifiers based on a namespace and a name. It is a deterministic generation method, meaning that for the same namespace and name, the same UUIDv3 will always be produced. This contrasts with UUIDv1 and UUIDv4 which are based on time and random numbers respectively.

The generation process for UUIDv3 involves taking a namespace UUID and a name (a string) and applying the MD5 hashing algorithm to them. The resulting MD5 hash is then manipulated according to the UUID specification to produce a 128-bit identifier. The version bits are set to '3', and the variant bits are set to indicate a RFC 4122 compliant UUID.

The purpose of UUIDv3 is to create stable, unique identifiers for resources where the identity is derived from an existing, well-defined name within a specific context. For example, it can be used to generate unique IDs for objects based on their fully qualified domain names within a predefined namespace. This determinism makes it useful for applications where consistent identification is crucial, such as in databases or distributed systems where the same entity needs to be reliably referenced across different instances. However, it's important to note that the security of MD5 has been questioned, and for cryptographic purposes, UUIDv5 which uses SHA-1 is generally preferred.