I am not sure what you are asking. UUID version 4 uuids use the crypto/rand package. I was concerned about collisions when I wrote the package so did some research, which you find in a comment:
// The strength of the UUIDs is based on the strength of the crypto/rand
// package.
//
// A note about uniqueness derived from the UUID Wikipedia entry:
//
// Randomly generated UUIDs have 122 random bits. One's annual risk of being
// hit by a meteorite is estimated to be one chance in 17 billion, that
// means the probability is about 0.00000000006 (6 × 10−11),
// equivalent to the odds of creating a few tens of trillions of UUIDs in a
// year and having one duplicate.
Version 1 UUIDs are based on the system ID (MAC address) and current time so they are much more predictable. Version 4 are the default.
I am not sure what you are asking. UUID version 4 uuids use the crypto/rand package. I was concerned about collisions when I wrote the package so did some research, which you find in a comment:
// The strength of the UUIDs is based on the strength of the crypto/rand // package. // // A note about uniqueness derived from the UUID Wikipedia entry: // // Randomly generated UUIDs have 122 random bits. One's annual risk of being // hit by a meteorite is estimated to be one chance in 17 billion, that // means the probability is about 0.00000000006 (6 × 10−11), // equivalent to the odds of creating a few tens of trillions of UUIDs in a // year and having one duplicate.
Version 1 UUIDs are based on the system ID (MAC address) and current time so they are much more predictable. Version 4 are the default.