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Topic: same public key (Read 3210 times)

legendary
Activity: 2646
Merit: 1137
All paid signature campaigns should be banned.
July 02, 2013, 11:38:09 AM
#62
Really? Is there more information on this?

March's fork.
The fallout from that fork was "healed" a long time ago.
legendary
Activity: 1002
Merit: 1000
Bitcoin
July 02, 2013, 09:14:53 AM
#61
How do you prevent yourself from being simultaneously struck by lightening and a meteorite while also being bitten by a mosquito that gives you West Nile virus as your house is being swallowed by a sinkhole caused by an earthquake?

Speaking probability, this is quite, to be more accurate, I would add : at the exact same moment of all those event, you hear at the radio the you have won the big prize at the lottery, and you turn blind in an instant, because of a mysterious unknow disease !
legendary
Activity: 1372
Merit: 1008
1davout
July 02, 2013, 08:39:31 AM
#60
Really? Is there more information on this?

March's fork.
legendary
Activity: 1862
Merit: 1011
Reverse engineer from time to time
July 02, 2013, 08:17:06 AM
#59
You can't double money in bitcoin.

Yes you can, happened back in march Cheesy
Really? Is there more information on this?
member
Activity: 63
Merit: 10
Vires in Numeris
July 02, 2013, 08:16:39 AM
#58
However, there could be a RIPEMD-160 hash collision of two different ECDSA pubkey point. That would have two different privkeys with one pubkey.

their would be 2 keypairs, where the hash of the public keys would be equal.

keypair A: (Apub, Apriv)
keypair B: (Bpub, Bpriv)

Apub != Bpub and Apriv != Bpriv

BUT!!!!!

hash(Apub) == hash(Bpub)
Yes. However, that would mean that the bitcoin address itself would be the same. Funds sent to that bitcoin address could be spent by either private key; the txout script only checks the hash of the pubkey key, not the public key itself.
legendary
Activity: 1050
Merit: 1000
You are WRONG!
July 02, 2013, 04:06:07 AM
#57
However, there could be a RIPEMD-160 hash collision of two different ECDSA pubkey point. That would have two different privkeys with one pubkey.

their would be 2 keypairs, where the hash of the public keys would be equal.

keypair A: (Apub, Apriv)
keypair B: (Bpub, Bpriv)

Apub != Bpub and Apriv != Bpriv

BUT!!!!!

hash(Apub) == hash(Bpub)
legendary
Activity: 1176
Merit: 1280
May Bitcoin be touched by his Noodly Appendage
July 02, 2013, 02:12:32 AM
#56
I want to repeat something:

An address corresponds to around 2^96 (around 8e28) different private keys
legendary
Activity: 1372
Merit: 1008
1davout
July 02, 2013, 02:08:12 AM
#55
However, there could be a RIPEMD-160 hash collision of two different ECDSA pubkey point. That would have two different privkeys with one pubkey.

Re-read yourself :-)
member
Activity: 63
Merit: 10
Vires in Numeris
July 01, 2013, 09:23:37 PM
#54
ok, so having the same adress means actually the same private key.

That makes sense.

Thank you!
However, there could be a RIPEMD-160 hash collision of two different ECDSA pubkey point. That would have two different privkeys with one pubkey.
legendary
Activity: 1400
Merit: 1013
July 01, 2013, 08:57:39 PM
#53
There are deterministic wallets which derive all the private keys from a 256 bit root key and a 256 bit chain code for a total  of 512 bits of entropy.

The odds of a collision that would allow an attacker to derive the entire sequence of private keys is even more unpossible than finding one of the 296 private keys whose public key generates the same hash as a known bitcoin address.
donator
Activity: 1218
Merit: 1079
Gerald Davis
July 01, 2013, 08:38:00 PM
#52
D&T,

You're getting slow.

 Grin

Yeah I am slipping in my old (forum) age.
full member
Activity: 182
Merit: 100
July 01, 2013, 08:36:27 PM
#51
Thank you both for the clarification. Your assumptions were correct: a) I was referring to the Qt client and b) I thought there was just one private key from which all public keys derived.

Learned something! Thanks again!
legendary
Activity: 3472
Merit: 4801
July 01, 2013, 08:32:34 PM
#50
D&T,

You're getting slow.

 Grin
donator
Activity: 1218
Merit: 1079
Gerald Davis
July 01, 2013, 08:29:54 PM
#49
But if the private keys are the same, doesn't that also mean that they will create the same "universe" of public keys?

What I mean is this: if you create a new wallet it has one address and the private key. When you create new addresses for that wallet all derive from the same private key. If two private keys are identical won't they eventually create the same addresses? (Whether they show in your address book or not (yet))?

There is no such thing as a "universe of private keys".  Your wallet contains 1 private key for each public key (and address).

There are deterministic wallets which use a seed to produce multiple addresses but the seed isn't the private key.  The seed allows one to create multiple private keys (one private key for each address) from a single seed.

You likely are (incorrectly) assuming a wallet has only one single private key for all the addresses. If your wallet has 1000 addresses you have 1,000 unique private keys.
legendary
Activity: 3472
Merit: 4801
July 01, 2013, 08:27:17 PM
#48
But if the private keys are the same, doesn't that also mean that they will create the same "universe" of public keys?

It was never stated, but I've been working off the assumption that we are talking about the Bitcoin-Qt wallet.  The Bitcoin-Qt wallet does not use a deterministic algorithm for generating bitcoin private keys or addresses.  Every new address is generated completely at random and has no mathematical association with any of the other addresses or private keys in the wallet.

What I mean is this: if you create a new wallet it has one address and the private key. When you create new addresses for that wallet all derive from the same private key.

No.  Regardless of the wallet you are using, each address has it's own private key.  When you create new addresses for the wallet, the wallet creates a new private/public key pair, and then computes the address from this new keypair.  In a deterministic wallet (such as Electrum), a deterministic algorithm is used to generate the next private key in the sequence instead of generating a random private key, but it is still a new private key.

If two private keys are identical won't they eventually create the same addresses? (Whether they show in your address book or not (yet))?

A private key only has one address associated with it.  (Well technically two, but that's due to the difference between the address that you get when you use a compressed public key and the one you get with an uncompressed public key)  If two private keys are identical, the address they create will be the same.

full member
Activity: 182
Merit: 100
July 01, 2013, 08:04:08 PM
#47
But if the private keys are the same, doesn't that also mean that they will create the same "universe" of public keys?

What I mean is this: if you create a new wallet it has one address and the private key. When you create new addresses for that wallet all derive from the same private key. If two private keys are identical won't they eventually create the same addresses? (Whether they show in your address book or not (yet))?
legendary
Activity: 3472
Merit: 4801
July 01, 2013, 07:53:42 PM
#46
Ok, so in other words: if the private keys are different but the addresses are the same that means that only the amount assigned to that address (balance on that particular address) can be spent by both parties NOT the total amount of the wallets of each party. Correct?

Correct.  Also, if the private keys ARE the same, that means that only the amount assigned to that address (balance on that particular address) can be spent by both parties NOT the total amount of the wallets of each party.

It doesn't matter if the private keys are the same or not.  It only matters if the private keys result in the same address.
full member
Activity: 182
Merit: 100
July 01, 2013, 07:45:41 PM
#45
Ok, so in other words: if the private keys are different but the addresses are the same that means that only the amount assigned to that address (balance on that particular address) can be spent by both parties NOT the total amount of the wallets of each party. Correct?
legendary
Activity: 3472
Merit: 4801
July 01, 2013, 07:31:31 PM
#44
The pub is derived from the priv, so if you had the pub you would also have the priv.

More than one private key can technically result in the same bitcoin address.

Therefore, if you have the same private key then you have the same address, but if you have the same address, you don't necessarily have the same private key.


In other words if Alice has a wallet that contains the address xyz and Bob has a wallet that contains the same address xyz
both have the same private key?

(And thus all individual addresses of Alice and Bob can be signed with their own or the other one's private key?)

Not necessarily, but they both have a private key that will create a valid signature for spending bitcoins that are associated with address xyz.  Not all individual addresses, only address xyz.


ok, so having the same adress means actually the same private key.

That makes sense.

Thank you!

No, having the same private key means having the same address.  Having the the same address does not necessarily mean having the same private key, but as long as you have a private key that is a valid private key for the address you are able to spend the bitcoins at that address.


donator
Activity: 1218
Merit: 1079
Gerald Davis
July 01, 2013, 07:31:01 PM
#43
In other words if Alice has a wallet that contains the address xyz and Bob has a wallet that contains the same address xyz
both have the same private key?

(And thus all individual addresses of Alice and Bob can be signed with their own or the other one's private key?)

Well it is slightly more complex.  It is possible that Alice and Bob have different private keys which produce the same address because addresses are a hash of the public key.  If that happens (essentially 0% chance) either private key can sign a transaction to spend coins sent to the address in question.
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