How unique are the Bitcoin addresses ?

[OmegaStarScream]

I just want to know how unique the addresses are ?
All of addresses start either with 1 or 3 (If it's multi signature) Yes but If we take this address for example :
3KfPAawFK8qG8KmRBHfkyNtvJwSLwHDJam

What are the chances that I will find another address that start with same way as the one posted above and what are the number of characters that could be the same ?

[Aamir1]

I just want to know how unique the addresses are ?
All of addresses start either with 1 or 3 (If it's multi signature) Yes but If we take this address for example :
3KfPAawFK8qG8KmRBHfkyNtvJwSLwHDJam

What are the chances that I will find another address that start with same way as the one posted above and what are the number of characters that could be the same ?

Ofcourse all bitcoin addresses are unique, but i think someone can surely find some other addresses that will have some character that matches from another address, they cannot be exactly the same but some of their characters can match each other, for example if one address is 1LqtG2r4 and the other one is 1tDw2r4, you can see that there are some matching letters in both, but both of them are unique when written completely.

[Pursuer]

I just want to know how unique the addresses are ?
All of addresses start either with 1 or 3 (If it's multi signature) Yes but If we take this address for example :
3KfPAawFK8qG8KmRBHfkyNtvJwSLwHDJam

What are the chances that I will find another address that start with same way as the one posted above and what are the number of characters that could be the same ?

this question has been asked as many times as there is bitcoin addresses

just search for bitcoin address collision and you will find your answer
here is a little help: https://bitcointalk.org/index.php?topic=104461.0

[OmegaStarScream]

Alright , thanks for both your answers
but I'm not speaking about an "exact" match or about "few separated letters" match , I'm speaking about a match like this for example :

#1 Address : 3KfPAawFK..........
#2 Address : 3KfPAawFA..........

[Lauda]

#1 Address : 3KfPAawFK..........
#2 Address : 3KfPAawFA..........

The chances would be very unlikely (you don't want people to calculate the exact %). Basically, it comes down to the starting String itself (length and the characters used). Obviously, something starting as 3housee would be much easier to encounter/generate than something as 3KfPAawFK. Additionally, one could always try to use vanitygen to generate an address with the same starting String.

[DannyHamilton]

What are the chances that I will find another address that start with same way as the one posted above and what are the number of characters that could be the same ?

That depends on how many addresses you generate, and how many characters you match.

For example, if you generate only two version 1 addresses (P2PKH), there is a 100% chance that the first character will match.

Each additional character that you want to match reduces the odds of finding a match.  Each additional address that you generate increases the odds of finding a match.

[shorena]

What are the chances that I will find another address that start with same way as the one posted above and what are the number of characters that could be the same ?

That depends on how many addresses you generate, and how many characters you match.

For example, if you generate only two version 1 addresses (P2PKH), there is a 100% chance that the first character will match.

Each additional character that you want to match reduces the odds of finding a match.  Each additional address that you generate increases the odds of finding a match.

...by 1 in 58. Since addresses are encoded in base58 the 2nd address has a ~1.7% chance to match the second character of the first. This is not the whole truth as the underlying bit pattern can make matching certain characters more difficult than others. Some quick examples from vanitygen (note the change in difficulty):

Code:

-snip->vanitygen.exe 12
Difficulty: 23
Pattern: 12
Address: 12TYiaUTWWnRvgVqLQ7jVcUqRQvDr8mbAt
Privkey: 5KZE53Z6emYutnErqfBg4jNSmXj2fBXkPgnmQPSnfCe9CArTTPf

-snip->vanitygen.exe 1g
Difficulty: 1353
Pattern: 1g
Address: 1grm3UJo2MB7SbaPGfGKg5mjKUKRj6o8i
Privkey: 5KPQRwF81tiSrAzGxYGQyKKUxh1Rjw5VcB4GStiTTsgejrvV93K

-snip->vanitygen.exe 1G
Difficulty: 22
Pattern: 1G
Address: 1G1daexbm4uxq1cUgfKkBynE6Z6ToVTtaE
Privkey: 5JFkakSypDRAb7qxgjCyb9XgdJWNFRvbaBHR8cvAWgR66w1Z15P

-snip->vanitygen.exe 11
Difficulty: 256
Pattern: 11
Address: 113kqszfLHxNcL6e3CPVNV9wAgmKcFERvb
Privkey: 5JFRDBmcPMKDtYEWAzBaBRdvkkucExj9RRNeEq2nikS97Fui6Dm

[OmegaStarScream]

I guess I understand now . Thanks , all of you .