Topic: Half of any bitcoin (crypto) public key - (public key half) (Read 2609 times)

point division. but you won't be splitting the private key when applied.

It won't work because that AI is an idiot, lol there is no SHA256 involved in finding k from p, and there is no "dividing" repeatedly until finding G, what AI can suggest is the worst way possible to brute force because it's an imbecile computer.😅

chatGPT suggest this..

It won't work because the math to do it (correctly) is not known

https://rawcdn.githack.com/nlitsme/bitcoinexplainer/aa50e86e8c72c04a7986f5f7c43bc2f98df94107/ecdsacrack.html

BRO, would you please give a little help how to use this calculator that you've referred above? I mean how to calculate half point, where should I put my public key whose half I am interested in.... Much appreciate your above help though

this from MrMaxwell might suit you very simple to use
https://github.com/MrMaxweII/Secp256k1-Calculator
On the other hand if you want to divide a pubkey which corresponds to an odd pk you will have its half etc etc... deleting the float is another much more complicated story. In short, dividing a pubkey in half will not help you much unless you know the starting pk

Guys, I hope you are all doing great!
Can anyone please refer some python script that can apply this halving thing on public keys and calculates its half???

i know about substracting is more good, but, if you thant get 80vbit from 120 is very hard too do it this because needs about  1 099 511 627 776 -1 substraction.

dividing with float part sovs with fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0342ec8 with not 02 03  pubkey but with pubkey *-1, this transform priv/pubkey in for from 12345 to fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0361108 form and you not  get negative number then substract because 12345 - 12346 = -1, and you range will jamp dramnaticaly from 5 chars to fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364140chard

, but if substract 123456 from fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0361108 - 123456 =  0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0342ec8 and range not jump.

Obviously your divisor (d) must be 2 if you are trying to downgrade a PK by 1 bit. Then the remainder will only be 1 or 0.

But subtraction does not really eliminate the float part by subtracting 1, you will either get the same pubkey when you multiply it again or a different one, so if the (quotient-1) subtraction gives you a different public key when its multiplied, you know that the quotient is an even private key.

Not that private key parities correspond to public key parities (they do *not* correlate), so the parity of the private key is still unknown. You are basically throwing away 1 bit of privte key during each division without further information about the private key composition.

How can we can fine half like this?


2**120
1329227995784915872903807060280344576

private key = 1329227995784915872903807060280344576

1329227995784915872903807060280344576 hex = 1000000000000000000000000000000

binary = 1000000000000000000000000000000000000000000000000000000000000000000000000000000 000000000000000000000000000000000000000000

Half binary first (60) = 100000000000000000000000000000000000000000000000000000000000

(hex) 800000000000000  = (dec) 576460752303423488

half of 1329227995784915872903807060280344576 is 576460752303423488

halvig has a int and float part, veryvery hard divide pubkey without flot part, but posible use combination  x / d = result1, result 1- 1(uno) =  result 2, result2 x d = downgraded pubkey = pubkey without int part.

divide 120 pub to 119, substract 1, multiply to 119 you get result 118 etc...
....

half of base point, pubkey, privkey,  /2, * 7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a1

this is a all half

What meaning is Half of any bitcoin?
Do you mean half of the public key right?
or
Did you mean half of the scalar to the private key right? or what?

this pubkey is odd 022b4ea0a797a443d293ef5cff444f4979f06acfebd7e86d277475656138385b6c but privkey is even  19 in des, so imposible start with even privkey then use 02... pubkeys,.  02...,03...., nit always correlate with odd even parametr unfortunately

DES PKEY = 19
HEX PKEY = 0x13
Pubkey   = 022b4ea0a797a443d293ef5cff444f4979f06acfebd7e86d277475656138385b6c


x= 0x2b4ea0a797a443d293ef5cff444f4979f06acfebd7e86d277475656138385b6c
y= 0x85e89bc037945d93b343083b5a1c86131a01f60c50269763b570c854e5c09b7a

div xy :
0x1c2bd878b94169da722a9de0c4e317cea8802aa96045830111a89d1d9de4270cL 0xf6a4826643c20ce10f240e855f610eb78e5193a278f1418ae0ad55515b71ff6aL

(div xy) - 1 :
0x41f7fa0a9a59513ae221e3b84b91995fc9d40eb5d120a6d8e663452ad92099c8L 0xf7ec24416d13b49dda2e33a1a7df14482423d69b2a22e54c21543145a186befdL

(div xy) - xy :
0x1c2bd878b94169da722a9de0c4e317cea8802aa96045830111a89d1d9de4270cL 0x95b7d99bc3df31ef0dbf17aa09ef14871ae6c5d870ebe751f52aaada48dfcc5L




double xy :
0xb699a30e6e184cdfa88ac16c7d80bffd38e2e1fc705821ea69cd5fdf1691fff7L 0xd505700c51d860ce5a096ee637ebed3bd9d7268126c76a16b745bc318a51ab04L

(double xy)+1 :
0x80c60ad0040f27dade5b4b06c408e56b2c50e9f56b9b8b425e555c2f86308b6fL 0x1c38303f1cc5c30f26e66bad7fe72f70a65eed4cbe7024eb1aa01f56430bd57aL

(double xy)+xy :
0x2600ca4b282cb986f85d0f1709979d8b44a09c07cb86d7c124497bc86f082120L 0x4119b88753c15bd6a693b03fcddbb45d5ac6be74ab5f0ef44b0be9475a7e4b40L

"priv even pub odd, shit"...  am i missing something??

try halving and substract, ie reverse of double and add

13 priv

022B4EA0A797A443D293EF5CFF444F4979F06ACFEBD7E86D277475656138385B6C  - pub

priv even pub odd, shit

"the output is

x = c62c910e502cb615a27c58512b6cc2c94f5742f76cb3d12ec993400a3695d413
y = 17f3dadd767275ddd3b23f46723631778bf01dadaebb9a953cf068712457c010 "

to get scalar_pkey the xy above:

modinv2 = modinv(2, N)
             =  57896044618658097711785492504343953926418782139537452191302581570759080747169 == ((N-1)/2)+1) or invers ((N-1)/2)

pkey xy = private key 3  * modinv2 % N
            = 3 * 57896044618658097711785492504343953926418782139537452191302581570759080747169 % N
            = 173688133855974293135356477513031861779256346418612356573907744712277242241507 % N
            = 57896044618658097711785492504343953926418782139537452191302581570759080747170

**applies to all odd privatekey values

The private key      : 0x7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a2L
Dec private key      : 57896044618658097711785492504343953926418782139537452191302581570759080747170
Biner private key   : 1111111111111111111111111111111111111111111111111111111111111111111111111111111 1111111111111111111111111111111111111111111111110101110101010111011011100111001 1010101111010010001010000000111011101111111101001001011110100011001101000000110 110010000010100010

the uncompressed DEC public key (not address):
(89636686429439908262420422079980100111093242688153882571369946125714247242771L, 10834049905482024808827094233028503931704324296739647619935835709590451240976L)

the uncompressed HEX public key (not address):
(0xc62c910e502cb615a27c58512b6cc2c94f5742f76cb3d12ec993400a3695d413L, 0x17f3dadd767275ddd3b23f46723631778bf01dadaebb9a953cf068712457c010L)

the uncompressed public key (HEX):
04c62c910e502cb615a27c58512b6cc2c94f5742f76cb3d12ec993400a3695d41317f3dadd76727 5ddd3b23f46723631778bf01dadaebb9a953cf068712457c010

the official Public Key - compressed:
02c62c910e502cb615a27c58512b6cc2c94f5742f76cb3d12ec993400a3695d413



Notice :
there is a doubling of scalar numbers either even or odd,
exm1 :
11 ECdouble => 22 ECdiv =>  11
13 ECdouble => 26 ECdiv =>  13
20 ECdouble => 40 ECdiv =>  20 ECdiv =>  10 ECdiv =>  5
21 ECdouble => 42 ECdiv =>  21

but actually there is no division of the odd scalar pkey divided by 2, there is only a 1xGpoint subtraction, then the result can be divided by 2

Exm: binary 1001

sequentially 1 2 4 9
the value of 9 is actually 8+1

for the last binary division result (right) or to get the decimal value 4 of 9, you can't divide 9 by 2,
but first subtract 9 by 1 and then divide by 2 (8 / 2 = 4)

if forced 9/2 and using the above operation, the calculation result will go to
57896044618658097711785492504343953926418782139537452191302581570759080747173 (HEX:0x7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a5)

the uncompressed public key (not address):
(46399714550823657646711952010527975805134803763457644396793103212103067379801L, 109666243570543015459678453826250465783941922322291717279653226122816671713075L)

the official Public Key - compressed:
0366954eca0543426304036fc70fc0fe3381f5195e88433bc32c5a8a60341e2859


Exm2: binary 10010
sequentially 1 2 4 9 18

18 /2 = 9
(9-1)/2 = 4
4/2 = 2
2/2 = 1

you don't need the private key to make this computation and you can not compute the private key. this is just simple point multiplication as defined by elliptic curve algorithm but instead of the usual generator point you use another point on curve (ie. the public key) and instead of the private key you use another number (ie. 2^-1).
you can do this to any of the hundreds of thousands of public keys found on bitcoin blockchain without having private keys.

So sorta like this:

_p = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2FL
_r = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141L
_b = 0x0000000000000000000000000000000000000000000000000000000000000007L
_a = 0x0000000000000000000000000000000000000000000000000000000000000000L
_Gx = 0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798L
_Gy = 0x483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8L


But you do have to have the private key though?

It's easier than you might think. In fact, you can use any library that allows you to calculate the public key from a private key and replace the parameters:

# Elliptic curve parameters (secp256k1)

P = 2**256 - 2**32 - 977
N = 115792089237316195423570985008687907852837564279074904382605163141518161494337 --> original parameter
#N = 57896044618658097711785492504343953926418782139537452191302581570759080747169 --> here to divide by 2 for example
A = 0
B = 7
Gx = 55066263022277343669578718895168534326250603453777594175500187360389116729240 --> here put the key you want to divide
Gy = 32670510020758816978083085130507043184471273380659243275938904335757337482424 --> same for y coordinate
G = (Gx, Gy)