CodeIgniter-UUID is a CodeIgniter library enables you to create UUID's within CodeIgniter. Supported versions of UUID is v4 (random), v3 (MD5 hash) and v5 (SHA-1 hash).
//Output a v4 UUID
echo $this->uuid->v4();
//Output a v3 UUID from a name and namespace (if a valid UUID namespace is omitted, a v4 generated UUID will be used)
echo $this->uuid->v3('My Name', '8d3dc6d8-3a0d-4c03-8a04-1155445658f7');
echo $this->uuid->v3('My Name');
//Output a v5 UUID from a name and namespace (if a valid UUID namespace is omitted, a v4 generated UUID will be used)
echo $this->uuid->v5('My Name', '8d3dc6d8-3a0d-4c03-8a04-1155445658f7');
echo $this->uuid->v5('My Name');
For information on UUID, take a look at the following URL: http://en.wikipedia.org/wiki/Universally_unique_identifier