I thought these were called GUIDs. What is a UUID?
Per the draft spec referenced below these are synonymous:…UUIDs (Universally Unique IDentifier), also known as GUIDs (Globally
What is a UUID?
According to Wikipedia:“…an identifier standard used in software construction, standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE). The intent of UUIDs is to enable distributed systems to uniquely identify information without significant central coordination. Thus, anyone can create a UUID and use it to identify something with reasonable confidence that that identifier will never be unintentionally used by anyone for anything else. Information labelled with UUIDs can therefore be later combined into a single database without need to resolve name conflicts. The most widespread use of this standard is in Microsoft’s Globally Unique Identifiers (GUIDs) which implement this standard.
A UUID is essentially a 16-byte number and in its canonical form a UUID may look like this:
So these version 4 UUIDs are basically random numbers. Won’t my UUID collide with someone elses?There are 122 significant bits in a type 4 UUID. 2122 is a *very* large number. Assuming a random distribution of these bits, the probability of collission is *very* low. How is the “randomness” determined?
Under the hood java.util.UUID is creating an instance of SecureRandom and using that to generate new UUIDs. If you are using the default Sun provider and default java.security file, you are using a SHA1PRNG ( Pseudo Random Number Generator based on Secure Hash Algorigthm 1 ) seeded from the operating system.
# Select the source of seed data for SecureRandom. By default an
# attempt is made to use the entropy gathering device specified by
# the securerandom.source property. If an exception occurs when
# accessing the URL then the traditional system/thread activity
# algorithm is used.
# On Solaris and Linux systems, if file:/dev/urandom is specified and it
# exists, a special SecureRandom implementation is activated by default.
# This "NativePRNG" reads random bytes directly from /dev/urandom.
# On Windows systems, the URLs file:/dev/random and file:/dev/urandom
# enables use of the Microsoft CryptoAPI seed functionality.
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orbyone wrote:great, that seems exactly what I want. I hope real phones can still provide that information, since privacy issues could be involved here.
Katharnavas wrote:orbyone wrote:great, that seems exactly what I want. I hope real phones can still provide that information, since privacy issues could be involved here.
IS there any possibility to obtain IMEI number rather than IMSI which is UNIQUE in all mobile phones.
plusminus wrote:Hey guys,
appended some extra lines for the IMEI in the same Tutorial as above:
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