16  4363 
Jay,
You probably have better odds at winning the lottery. Seriously.
What is your concern?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Just wondering ... just candy for the mind.
I've heard someone say the odds are about the same as winning the Texas
lottery 32 times.
I was just hoping a formula or a number.
I slept though statistics, so I can't come up with a good answer.
--
Jay Douglas http://jaydouglas.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:O8**************@TK2MSFTNGP14.phx.gbl... Jay,
You probably have better odds at winning the lottery. Seriously.
What is your concern?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Probably not possible. Two computers would have to be built as exactly the
same time, have the same MAC address (normally impossible), and generate a
GUID at exactly the same time. (Actually, I vaguely remember that MS doesn't
use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Jay,
I remember reading something that said you had to generate 1000 new
GUIDs per second for the next 5000 years in order to come across a duplicate
(or something like that).
I wouldn't worry =)
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:Om**************@TK2MSFTNGP12.phx.gbl... Just wondering ... just candy for the mind.
I've heard someone say the odds are about the same as winning the Texas
lottery 32 times.
I was just hoping a formula or a number.
I slept though statistics, so I can't come up with a good answer.
--
Jay Douglas
http://jaydouglas.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote
in message news:O8**************@TK2MSFTNGP14.phx.gbl... Jay,
You probably have better odds at winning the lottery. Seriously.
What is your concern?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Okay math wizards, a Guid is 32 hexidecimal digits.
Each digit can be A-F or 0-9 which amounts to 16.
so, 32 possiblities of 16 characters .. what's the formula
--
Jay Douglas http://jaydouglas.com
"Jonathan Allen" <x@x.x> wrote in message
news:%2****************@TK2MSFTNGP09.phx.gbl... Probably not possible. Two computers would have to be built as exactly the
same time, have the same MAC address (normally impossible), and generate a
GUID at exactly the same time. (Actually, I vaguely remember that MS
doesn't use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Let's make this simpler. It's a 128 bit number, which means that there
are 2^128 possibilities. That turns out to be:
3.4028236692093846346337460743177e+38
That's a large number.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:Ou**************@TK2MSFTNGP15.phx.gbl... Okay math wizards, a Guid is 32 hexidecimal digits.
Each digit can be A-F or 0-9 which amounts to 16.
so, 32 possiblities of 16 characters .. what's the formula
--
Jay Douglas
http://jaydouglas.com
"Jonathan Allen" <x@x.x> wrote in message
news:%2****************@TK2MSFTNGP09.phx.gbl... Probably not possible. Two computers would have to be built as exactly
the same time, have the same MAC address (normally impossible), and
generate a GUID at exactly the same time. (Actually, I vaguely remember
that MS doesn't use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Nicholas Paldino [.NET/C# MVP] wrote: Jay,
I remember reading something that said you had to generate 1000 new
GUIDs per second for the next 5000 years in order to come across a duplicate
(or something like that).
I wouldn't worry =)
Which would be the same as 1 million new GUIDs per second for the next 5 years,
or 1 billion per second for the next couple of days, would it not? If it's that
easy, I would worry.
-rick-
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
Better than the odds of an incrementing numeric counter generating a
duplicate number.
SP
I thought its a combination of MAC address and current clock
tick(Year-Month-Day-HH:MM:SS:millisecond). So, probablility of getting a
duplicate is virtually 0.
"Jonathan Allen" wrote: Probably not possible. Two computers would have to be built as exactly the
same time, have the same MAC address (normally impossible), and generate a
GUID at exactly the same time. (Actually, I vaguely remember that MS doesn't
use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
but you can never be sure. since the guid is generated using a hashfunction
of the values you mentioned, errors in the implemention of the hashfunction
can lead to duplicated guids.
"Ravi Shankar" <Ravi Sh*****@discussions.microsoft.com> schrieb im
Newsbeitrag news:DF**********************************@microsof t.com... I thought its a combination of MAC address and current clock
tick(Year-Month-Day-HH:MM:SS:millisecond). So, probablility of getting a
duplicate is virtually 0.
"Jonathan Allen" wrote:
Probably not possible. Two computers would have to be built as exactly
the same time, have the same MAC address (normally impossible), and generate
a GUID at exactly the same time. (Actually, I vaguely remember that MS
doesn't use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
I thought that MS stopped using the MAC address to create the guids since
the cheaper NIC cards were producing duplicate MAC addresses at an alarming
rate.
--
Jay Douglas http://jaydouglas.com
"cody" <de********@gmx.de> wrote in message
news:eB**************@TK2MSFTNGP09.phx.gbl... but you can never be sure. since the guid is generated using a
hashfunction
of the values you mentioned, errors in the implemention of the
hashfunction
can lead to duplicated guids.
"Ravi Shankar" <Ravi Sh*****@discussions.microsoft.com> schrieb im
Newsbeitrag news:DF**********************************@microsof t.com... I thought its a combination of MAC address and current clock
tick(Year-Month-Day-HH:MM:SS:millisecond). So, probablility of getting a
duplicate is virtually 0.
"Jonathan Allen" wrote:
> Probably not possible. Two computers would have to be built as exactly the > same time, have the same MAC address (normally impossible), and
> generate a > GUID at exactly the same time. (Actually, I vaguely remember that MS doesn't > use the MAC address anymore, but I may be mistaken.)
>
> --
> Jonathan Allen
>
>
> "Jay Douglas" <ja****************@squarei.com> wrote in message
> news:OH**************@TK2MSFTNGP14.phx.gbl...
> > Does anybody know the odds of generating a duplicate guid?
> >
> > --
> > Jay Douglas
> > http://jaydouglas.com
> >
> >
> >
>
>
>
Nicholas,
Well put!
Taught me a little about coming up with the possibilities using the bit^2
deal too.
Thanks again.
--
Jay Douglas http://jaydouglas.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:OZ**************@TK2MSFTNGP09.phx.gbl... Let's make this simpler. It's a 128 bit number, which means that there
are 2^128 possibilities. That turns out to be:
3.4028236692093846346337460743177e+38
That's a large number.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:Ou**************@TK2MSFTNGP15.phx.gbl... Okay math wizards, a Guid is 32 hexidecimal digits.
Each digit can be A-F or 0-9 which amounts to 16.
so, 32 possiblities of 16 characters .. what's the formula
--
Jay Douglas
http://jaydouglas.com
"Jonathan Allen" <x@x.x> wrote in message
news:%2****************@TK2MSFTNGP09.phx.gbl... Probably not possible. Two computers would have to be built as exactly
the same time, have the same MAC address (normally impossible), and
generate a GUID at exactly the same time. (Actually, I vaguely remember
that MS doesn't use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl...
Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
MAC addresses aren't used any more to generate GUID's.
Willy.
"Jonathan Allen" <x@x.x> wrote in message
news:%2****************@TK2MSFTNGP09.phx.gbl... Probably not possible. Two computers would have to be built as exactly the
same time, have the same MAC address (normally impossible), and generate a
GUID at exactly the same time. (Actually, I vaguely remember that MS
doesn't use the MAC address anymore, but I may be mistaken.)
--
Jonathan Allen
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:OH**************@TK2MSFTNGP14.phx.gbl... Does anybody know the odds of generating a duplicate guid?
--
Jay Douglas
http://jaydouglas.com
"Jay Douglas" <ja****************@squarei.com> wrote in message
news:%2****************@TK2MSFTNGP10.phx.gbl... I thought that MS stopped using the MAC address to create the guids since
the cheaper NIC cards were producing duplicate MAC addresses at an alarming
rate.
--
Jay Douglas
http://jaydouglas.com
That's right, microsoft doesn't use the DCE algorithm on NT based systems
(since NT4 SP4), but the reason was a bit of "privacy paranoia", people
didn't like to give away their MAC addresses through a GUID.
Willy.
Willy Denoyette [MVP] wrote: "Jay Douglas" <ja****************@squarei.com> wrote in message
news:%2****************@TK2MSFTNGP10.phx.gbl...
I thought that MS stopped using the MAC address to create the guids since
the cheaper NIC cards were producing duplicate MAC addresses at an alarming
rate.
--
Jay Douglas
http://jaydouglas.com
That's right, microsoft doesn't use the DCE algorithm on NT based systems
(since NT4 SP4), but the reason was a bit of "privacy paranoia", people
didn't like to give away their MAC addresses through a GUID.
Willy.
Is the algorithm MS uses to create a GUID published somewhere?
-Mark
"Mark Rance" <sp******@nomail.com> wrote in message
news:z7********************@pcisys.net... Willy Denoyette [MVP] wrote: "Jay Douglas" <ja****************@squarei.com> wrote in message
news:%2****************@TK2MSFTNGP10.phx.gbl...
I thought that MS stopped using the MAC address to create the guids since
the cheaper NIC cards were producing duplicate MAC addresses at an
alarming rate.
--
Jay Douglas
http://jaydouglas.com
That's right, microsoft doesn't use the DCE algorithm on NT based systems
(since NT4 SP4), but the reason was a bit of "privacy paranoia", people
didn't like to give away their MAC addresses through a GUID.
Willy.
Is the algorithm MS uses to create a GUID published somewhere?
-Mark
..NET uses RNGCryptoServiceProvider which is a wrapper over the cryptographic
pseudorandom number generator inside CryptoAPI which in turn calls Win32's
API CryptGenRandom().Note that COM uses the same Win32 API but now through
CoCreateGuid().
I don't know the exact algorithm used by CryptGenRandom() and I don't think
it's a trade secret so I would suggest you to ask MSFT for details by
sending a mail to Brian LaMacchia ba*@microsoft.com
Willy. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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