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Topic: 2^96 same bitcoin address - page 3. (Read 920 times)

legendary
Activity: 1512
Merit: 7340
Farewell, Leo
October 05, 2021, 06:57:48 AM
#5
And note that this is just for an address type that encodes a RIPEMD-160 hash. In P2WSH, multi-sig addresses are encodings of a 256-bit number and thus, there aren't 296 private keys for each address on average. There isn't even 1 for each address. The total private keys that are valid are slightly lower than 2256.
copper member
Activity: 906
Merit: 2258
October 05, 2021, 03:41:27 AM
#4
Quote
Then we also have addresses made from hash of the scripts containing the public key so the number grows even more
Yes, 2^96 applies only to P2PKH or P2WPKH, in case of P2WSH the number of combinations is potentially unlimited, because there are many spendable scripts, for example " OP_CHECKSIGVERIFY OP_SIZE OP_EQUALVERIFY OP_HASH256 OP_EQUAL", then you can push any transaction up to 520 bytes on the stack and add your signature. Because MAX_SCRIPT_SIZE is set to something like 10,000 bytes, there could be even 2^80000 possible P2WSH addresses or something like that, so because they are 256-bit addresses, a lot of keys could be used to produce the same address.
legendary
Activity: 3472
Merit: 10611
October 04, 2021, 11:54:57 PM
#3
When you say "addresses" and not specify what type, then the answer is there are a lot more than the size of a RIPEMD160 hash because we have multiple types of addresses and 3 ways to represent public keys each creating a different hash. Then we also have addresses made from hash of the scripts containing the public key so the number grows even more (eg. P2(W)SH) and finally we have brand new addresses using the public key itself known as P2TR or witness version 1 addresses used in Taproot.

In short for each private key there are far more addresses than 2256.
copper member
Activity: 821
Merit: 1992
October 04, 2021, 11:33:58 PM
#2
Yes, because for each public key there is only one matching private key. Private to public key mapping is unique, 1:1. Public key to address mapping is not, because there are around 2^256 public keys that are mapped into around 2^160 addresses, so there are around 2^96 matching keys for each address, if you assume that they are distributed equally. For some address it may be above or below 2^96, but mathematically you can be 100% sure that there is some address with around 2^96 or more matching keys.
member
Activity: 206
Merit: 16
October 04, 2021, 10:46:39 PM
#1
Hello we know that there are 2^96 identical bitcoin addresses in the 2^256 private key.
Is it the same for the public keys?
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