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1  Other / Off-topic / I built a privacy-first visual CAPTCHA and a bot-protected URL Shortener on: March 17, 2026, 08:20:29 PM
Hey everyone,

Like most of you, I got completely fed up with the current state of bot protection. We are constantly forced to train corporate AI models by clicking endless grids of crosswalks and traffic lights, all while these widgets track our cross-site cookies.

So, I built a lightweight, privacy-friendly alternative from scratch: CAPTCHAL.ink







Instead of object recognition, it relies on human spatial awareness. You get a 3x3 grid of images, and the instruction is simple: Click the images that are upside down. Human brains instantly understand gravity and lighting direction, while modern bots struggle with this abstract physics context. Plus, it uses zero third-party cookies (works perfectly in strict Incognito mode).

While developers can drop this widget into their forms for free, I realized that many people wants URL shortener that will block bots.

Introducing the Bot-Protected URL Shortener:
https://captchal.ink/shortener.php

How it works:

Paste any long URL into the generator.

We give you a compact, clean link that is easy to share anywhere (tweets, bios, QR codes).

When someone clicks it, they must complete the simple visual challenge (finding the upside-down images).

Once verified, they are instantly redirected to your destination.

Why use this?

Visual proof-of-work: It strictly protects your destination links from bots, scrapers, and automated abuse.

Completely frictionless: No sign-up required. You can create and share protected links in seconds.

Unique & Secure: Each short link is unique and tightly tied to your destination URL.

The project is currently in its Public Beta phase and is entirely free to use. I'm an indie developer running this solo, so I am looking for early adopters to test it out "in the wild."

Try to use it, try to break it, and let me know your honest feedback!
2  Bitcoin / Development & Technical Discussion / 4 points with same doubling slope on: February 22, 2026, 10:36:58 PM
I found on secp256k1 that if 4 points have same doubling slope their private keys always gives 0
k1+k2+k3+k4=0

On smaller curve
P=967 N=907
β (cube root of 1): 142
λ (eigenvalue at P): 522
1G   (418, 442)


If I have 1st private key I can calculate 1st column.... and I can  calculate all slopes in 1 set of 24 points but I did not find the way to if I have k1 to calculate k2 k3 k4

Also on the big curve I found those sets

f(x) = 9x^4 - 4slope^2x^3 - 28slope^2 = 0

On this way I generated sets of 4 points 48 sets on this curve p=967
I tried other curves with Sagemath
p=1000003 - Number of points: 999006 Number of sets: 41886
p=1001023 - Points: 999066 - Sets:41466
p=1001527 - Points: 1000158 - Sets:41580
p=20000077 - Points: 19992876 - Sets:833040

Finally I tried to search those sets on the big curve. I started with slope 1 and I was searching if current slope will give 4 solutions for that
This is the SageMath code I was using https://justpaste.it/k055b
and I got these Slopes and X values

Slope 5:
e5493c5e5ab1e25795a4f01f362ebc855d3c2611100bb0c24b401d5846f28f93
95b49d5352c6d6893771e5524aced66e9c163010d1cf0dcad80a77d786fc4681
91bfb02411f3bbb0e380f649f876e8692acbb596452df00277c846b1191017f5
817b59b8797719a732f66d2814c4683114c58280bc858a53f32607aac3abb2ec
--------------------
Slope 16:
ff405d7729ed52aa591f7be3f59048c4d506fc28ff83f1b78c84f34c9ec19e50
a1f7ff943ae98653ce8e8b90ea104f1f9a669548bf0208a595810c0d526cb547
2fe5f2ec5aed03af8aae566b6a792fdf5ae94630ba878d2a0206ec505e7cd908
126fe8ebce7506e0868730589974711fc3e20bebbfd606b1bf814d375aff7748
--------------------
Slope 47:
d8a0a502488cf53fe88a7b53b3b86021c151e59ef8df9f0f6fe54b821cef7ac6
6ced29459069a670d859aec16c1e85d426d1eaf84a1a14f8beab86e85934b74b
5b260613d299e1e19673ccf072afac0b94e843b73f24fe1f425f1e2ca885df5b
42da6487e2a865fbe18b97335107a6e2112ccf3fb6c4dc11729e484a8c0095df
--------------------
Slope 54:
f9c2e48f573115eddcbc132f9cf5979ac292e3918ecdec4458589501788f5b90
caeb00411e5011e845e8063c58749613f6e51a083896b935cab902a50815f9c2
217212301587cca0fb1387de3db81428cb7b5e95567786fee35fc43327ea2046
19e008ff74f70b88e2485eb5ccddbe287b0ca3d0e223d386f98ea424577087d6
--------------------
Slope 110:
f494b668f9c24a74dcced225e670cd6d9b343b9d8175354123281ab73564f74a
a3c5694b0a6cce2d90e5cfdc9f3bd9a5bad9fab3a0685ece8a5bd958802b979c
35fbd7fee43dafc765aeb3abe77c60fcaba79fbebd7d5b5ffddd70c9acc27109
15384130a5cc1b246580388a766530d38c830d7e59889ec9382cd4084857b888
--------------------
About 16% of all points on the curve have this property
Of course if you know 1 slope then you know p-slope so in the case of any kind of scanning we can just save the slope and we have info for 8 points
Do you think that those points can be used for solving secp256k1? What do you think about all of this?

3  Other / Off-topic / Johnsboard.com - I was inspired by the guy that sold homepage on: November 20, 2025, 12:07:43 AM


https://www.johnsboard.com/

So my nickname is John (my real name is similar), and I created this website where you can submit your banner, and my homepage will link to your website (follow the link - opened in new tab). I saw the story about that guy who sold pixels, and I saw that the website is not working anymore. It is not updated... Most of the links are not working....

...so I wanted to make something new, similar but not the sam,e and basically my list will update regularly by itself...

Below my 10x20 banners grid (banners can be 100x50, so in total it is 1.000.000 pixels), you will find a detailed explanation of how my board works.

Please if you find any bugs, send me a message here or send me email at admin@johnsboard.com
(I am one man show so the bugs are possible to happen)

Thank you, and I am calling you to submit your website or any kind of "normal link", links to your projects, you can put refferal links just no adult torrent illegal - no links that redirects to something different

Thank you <3
4  Bitcoin / Development & Technical Discussion / I created smaller secp256k1 just for testing on: January 27, 2025, 10:56:02 PM
So I am learning about everything and so there is a chance that this post can be lame/noob or something like that

I created a smaller secp256k1, p=43 n=31
I took point G(2, 31) for the generator point and I got the list of all valid points
Code:
G=(2,31)
2G=(7,36)
3G=(35,22)
4G=(21,25)
5G=(12,31)
6G=(29,12)
7G=(25,25)
8G=(32,3)
9G=(20,3)
10G=(42,36)
11G=(40,18)
12G=(37,7)
13G=(13,22)
14G=(34,3)
15G=(38,22)
16G=(38,21)
17G=(34,40)
18G=(13,21)
19G=(37,36)
20G=(40,25)
21G=(42,7)
22G=(20,40)
23G=(32,40)
24G=(25,18)
25G=(29,31)
26G=(12,12)
27G=(21,18)
28G=(35,21)
29G=(7,7)
30G=(2,12)

I printed this and I put it on my wall so when I work (I work from home) sometimes I look into this paper and I tried to find something interesting (interesting for me Smiley )

so this is what I found and also those rules can be applied on regular secp256k1 that Bitcoin is using...

Every Y has 3 different X values... When you calculate G of those points you always get n=31
so G=(2,31) + 5G=(12,31) + 25G=(29,31) = 31G, also for all other points 2G=(7,36) + 10G=(42,36) + 19G=(37,36) = 31G
If you change generator points those positions will remain the same so for n=31 you will always get the same Y on the same sets of points 1 5 25, 2 10 19... there are 10 sets of this points

There are negative points set with 1 5 25 and 6 26 30 (6 26 30 starting from the "end" to start" basically) When you do positive set + negative set of points those point will always return 93G or 3n

I found that if you do for one set of point X1 + X2 +X3 you sometimes get 2P and sometimes get only P I do not know why...

so on original curve where y is 483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8
you have 3 X
first   x: c994b69768832bcbff5e9ab39ae8d1d3763bbf1e531bed98fe51de5ee84f50fb
second   x: 79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798
third   x: bcace2e99da01887ab0102b696902325872844067f15e98da7bba04400b88fcb

If you do X1 + X2 + X3 in this case you will get 2P in some other cases I found that I only get 1P
Y 4218f20ae6c646b363db68605822fb14264ca8d2587fdd6fbc750d587e76a7ee

first   x: 1
second   x: 7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee
third   x: 851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40
In this case you get only P when you do X1 + X2 + X3

I found that for symmetrical points if you do Y1+Y2 you always get P
b7c52588d95c3b9aa25b0403f1eef75702e84bb7597aabe663b82f6f04ef2777 + 79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798 = p
.
.
.

Is there and useful way that we can use those points if we can calculate their G positions? I am testing bigger and bigger curves and always looking for n that number of points mod 6 = 0 (+ infinity point)
p = 937 n = 973
1G 235G 737G

So I am trying to make a connection between 1st and 2nd point for any p and any n....
If I know 1st and 2nd point I can easily calculate 3rd = n - 1st - 2nd
then I can calculate the position of other 3 points that has different Y but same 3 X

If we know the relations between those points maybe we can scan keys faster or see some periodical groups I do not know
5  Bitcoin / Development & Technical Discussion / Secp256k1 returning half of 3G? on: December 17, 2024, 03:16:49 AM
So I am exploring this everything and I am learning a lot about bitcoin technical side and structure and also I am learning to programing at Python...

And I made like simple program where you can add dots on elliptic curve like Q+Q or Q+G and also I made G-Q, X*G and

 I made like Q:1/2 so this code will give me for 8G I will get 4G dot...

But when I did that for 3G I expected some error mistake or something because we do not have 1.5G...

So What am I doing wrong here? How I get the result for 3G... or 5G or any odd number * G

Thank you
6  Bitcoin / Development & Technical Discussion / Generating bitcoin public key - question for a school project :) on: November 16, 2021, 12:51:41 AM
So yes I did choose a topic for my college final exam. I will make a presentation about bitcoin and everything...

I know how technically the bitcoin address is generated but I just do not know how to generate a public key but just calculating with a "calculator"

So I tried to do it by myself...

I know that Sha256 1st private key 0000000...001 will give this public  key 0479BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798483ADA7726A3C 4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8
because this is the start point of G point (04 is the prefix then 64 letters are X and next 64 letters are Y)... So I understand this...

But in the case where I choose the second private key 0000000...002 I tried to do this...

I know for this multiplication so in my case number 2 is "10" binary so my multiplication will look like this

0 1*G

1 2*G

0 4*G

0 8*G

0 16*G

0 32*G

0 64*G

0 128*G

...

So I tried to do this manually Smiley (I know PHP GMP functions)

Hex to decimal "79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798483ADA7726A3C46 55DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8" = 6376237641841063197511976314280597438149211753541909917794154839912978489307502 705320406087313832827571435203289817719151821525032884964596839752540411064

Then I did 2G and I got
1275247528368212639502395262856119487629842350708381983558830967982595697861500 5410640812174627665655142870406579635438303643050065769929193679505080822128

Now dec to hex
F37CCCFDF3B97758AB40C52B9D0E160E0537F9B65B9C51B2B3E502B62DF02F309075B4EE4D4788C ABB49F7F81C221151FA2F68914D0AA833388FA11FF621A970
And I should add 04 on the beginning ... but I found that this is not a public key of private key 2
Correct public key is
04C6047F9441ED7D6D3045406E95C07CD85C778E4B8CEF3CA7ABAC09B95C709EE51AE168FEA63DC 339A3C58419466CEAEEF7F632653266D0E1236431A950CFE52A

so what I did wrong?
7  Economy / Invites & Accounts / Selling 326 TH account - Hashflare on: May 21, 2018, 09:53:29 PM
How much money I can get if I offer the 326TH contract on sale. The contract will last until mid of December.

This is the proof that I own this account

http://prntscr.com/jkvbqq
8  Bitcoin / Development & Technical Discussion / Addresses with 0.00005460 BTCs history on: March 17, 2018, 10:08:05 PM
I know PHP so I made something like Brainwallet brute force... I made it record every address that has been used then it will monitoring all founded address because maybe they will be used again in the future.

So I founded a lot of address where 0.00005460 BTCs are received and 0.00005460 BTCs are sent. That's it. Why this amount and why so many addresses Wink
9  Bitcoin / Wallet software / Is there any way to import Bitcoin private keys from TXT file on: March 10, 2018, 04:35:31 PM
I need something like - I paste list of private keys and click "OK"

or

Browse - and I found txt file where are my private keys and then I click OK...
10  Bitcoin / Wallet software / 12 words to valid bitcoin address with PHP on: November 24, 2017, 12:09:58 PM
Hello. I want to ask does anyone have PHP function or class or something about this problem.
I want to generate valid bitcoin address from "12 words"

I want to register 1 address for each user that register on my website. Each address must be unique and Valid.

Is this even possible??? Thank you for help
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