How do y'all know how many bits a public key is?
It is not possible to know the private key bit length from the public key
MrFreeDragon, I have question for you if you can explain to me please !! how brainless can find that those address are 100bits ?
let think that he take the 110 address and try to add negative hex numbres to reduce the bit ,right !! but even that how he can be sure that the numbre that he add make address from 110bit to 100bit !!? that is really weird
the only thing that we know is 2^n = 2^(n-1) + 2^(n-2) .....+ 2^(n-n+1) + 2 !!
but if we have "n" =in range 110 and 111 that make impossible to know of even predict the bit of wallet.
if you have any idea please.
thanks
It is not possible to know the bit length just from the public key. It is not possible. Probably the author of that argument has some additional details. But it is not possible to know it just from the public key.
Publlic key is a Point with x-coordinate up to almost 2^256 (actually the maximum value is module which is close to 2^256). Take the easy example with 1bit key (which is actually number 1). For private key 1, the public key is 0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798, and this number is something like 47% on the whole range of the keys, and it is also the number approximately 2^254.92, so it is 254bit number. Hence, for 1bit private key we have 254bit x-coordinate of the public key. It is not possible to know the bit length of the private key based just on the public key.
ECDSA is one way: it is possible to receive the public key from the private, bit not vice versa.
