After a night of searching the answer to the question bothering me (and not finding the answer), I can get the answer here ... The issue concerns the address 105 which has outgoing transactions and to which I know the pub (in HEX). How should I convert it to a string consisting ONLY OF NUMBERS .... From these patterns my head is already breaking and the level of knowledge in this direction has not changed. He understands that this is the index value 'x' or 'y', that for these addresses we have only 'y' because it's compressed, etc., but where do the DEC values come from in various Python scripts? Guest gives to try to find a value in the range of 2 ^ 20, giving me the index value 'y' consisting of 155 digits ...
I tried to transform it in a different way and I have no chance to approach this number ... it does not even occur to me what can be converted 33-character hex string being a compressed publickey to give it 155 digits being ... well, ... what other than the index? :-)
I apologize in advance for a vague description, but as I mentioned at the beginning ... the whole night does its job. Greetings!
There appears to be a few misunderstandings in your post. Specifically the part in bold is wrong. x and y are not "indexes" they are coordinates.
A
private key is a number between 1 and a little bit less than 2
256A
public key is a point on a curve in two dimensional space. Therefore it has and x coordinate and a y coordinate.
The x coordinate and y coordinate are both binary numbers in the range 2
256.
For the curve used for Bitcoin public keys it turns out that for every x coordinate there are two possible y coordinates.
A full public key give you both the x coordinate and y coordinate of the point that is the public key.
A compressed public key give you the x coordinate and the sign of the y coordinate so in order to convert it to a full public key you have to calculate the correct y coordinate from the x coordinate.
The script above does just that: calculates the correct y coordinate from the x coordinate and the sign of the y coordinate.